Data Sheet AS5245 Programmable 360 Magnetic Angle Encoder with Absolute SSI and PWM Output 1 General Description Two digital 12-bit absolute outputs Quadrature A/B (10- or 12-bit) and Index output signal The AS5245 is a contactless magnetic angle encoder for accurate measurement up to 360 and includes two AS5145 devices in a punched stacked leadframe. User programmable zero position Failure detection mode for magnet placement monitoring and loss of power supply It is a system-on-chip, combining integrated Hall elements, analog front end and digital signal processing in a single device. "Red-Yellow-Green" indicators display placement of magnet in Z-axis To measure the angle, only a simple two-pole magnet, rotating over the center of the chip is required. The magnet may be placed above or below the IC. Tolerant to magnet misalignment and air gap variations Wide temperature range: - 40C to +150C The absolute angle measurement provides instant indication of the magnet's angular position with a resolution of 0.0879 = 4096 positions per revolution. This digital data is available as a serial bit stream and as a PWM signal. An internal voltage regulator allows operation of the AS5245 from 3.3V or 5.0V supplies. The AS5245 is fully automotive qualified to AEC-Q100, grade 0. 2 Key Features Contactless high resolution rotational position encoding over a full turn of 360 Unique Chip Identifier Fully automotive qualified to AEC-Q100, grade 0 Small package: QFN 32 LD (7x7) 3 Applications The AS5245 is ideal for applications with an angular travel range from a few degrees up to a full turn of 360. The device is suitable for Automotive applications like Throttle position sensors, Gas/brake pedal position sensing, Headlight position control, Contactless rotary position sensing, Front panel rotary switches and Replacement of potentiometer. Figure 1. AS5245 Block Diagram VDD3V3 VDD5V MagINCn MagDECn LDO 3.3V PWM Interface Sin Hall Array & Frontend Amplifier Mux Cos PWM Ang DSP Mag Absolute Interface (SSI) DO CSn CLK OTP Register AS5245 PDIO Incremental Interface DTEST1_A DTEST2_B Mode_Index Note: This Block Diagram presents only one die www.austriamicrosystems.com/AS5245 Revision 1.3 1 - 33 AS5245 Data Sheet - C o n t e n t s Contents 1 General Description .................................................................................................................................................................. 1 2 Key Features............................................................................................................................................................................. 1 3 Applications............................................................................................................................................................................... 1 4 Pin Assignments ....................................................................................................................................................................... 4 4.1 Pin Descriptions.................................................................................................................................................................................... 5 5 Absolute Maximum Ratings ...................................................................................................................................................... 6 6 Electrical Characteristics........................................................................................................................................................... 7 6.1 Magnetic Input Specification................................................................................................................................................................. 8 6.2 System Specifications .......................................................................................................................................................................... 9 7 Timing Characteristics ............................................................................................................................................................ 11 8 Detailed Description................................................................................................................................................................ 12 8.1 Mode_Index Pin.................................................................................................................................................................................. 8.2 Synchronous Serial Interface (SSI) .................................................................................................................................................... 8.2.1 8.2.2 8.2.3 8.2.4 8.2.5 8.2.6 Serial Data Contents.................................................................................................................................................................. Z-axis Range Indication (Push Button Feature, Red/Yellow/Green Indicator)........................................................................... Incremental Mode ...................................................................................................................................................................... Sync Mode................................................................................................................................................................................. Sine/Cosine Mode ..................................................................................................................................................................... Daisy Chain Mode ..................................................................................................................................................................... 8.3 Pulse Width Modulation (PWM) Output.............................................................................................................................................. 12 13 13 14 14 16 16 16 17 8.3.1 Changing the PWM Frequency.................................................................................................................................................. 18 8.4 Analog Output..................................................................................................................................................................................... 9 Application Information ........................................................................................................................................................... 19 9.1 Programming the AS5245 .................................................................................................................................................................. 9.1.1 9.1.2 9.1.3 9.1.4 9.1.5 9.1.6 18 Zero Position Programming ....................................................................................................................................................... OTP Memory Assignment.......................................................................................................................................................... User Selectable Settings ........................................................................................................................................................... OTP Default Setting................................................................................................................................................................... Redundancy............................................................................................................................................................................... Redundant Programming Option ............................................................................................................................................... 9.2 Alignment Mode.................................................................................................................................................................................. 19 19 20 20 21 21 21 22 9.3 3.3V / 5V Operation ............................................................................................................................................................................ 23 9.4 Choosing the Proper Magnet.............................................................................................................................................................. 24 9.5 Failure Diagnostics ............................................................................................................................................................................. 25 9.5.1 Magnetic Field Strength Diagnosis ............................................................................................................................................ 25 9.5.2 Power Supply Failure Detection ................................................................................................................................................ 25 9.6 Angular Output Tolerances ................................................................................................................................................................. 9.6.1 9.6.2 9.6.3 9.6.4 9.6.5 9.6.6 9.6.7 Accuracy .................................................................................................................................................................................... Transition Noise......................................................................................................................................................................... High Speed Operation ............................................................................................................................................................... Propagation Delays ................................................................................................................................................................... Internal Timing Tolerance .......................................................................................................................................................... Temperature .............................................................................................................................................................................. Accuracy over Temperature ...................................................................................................................................................... 9.7 AS5245 Differences to AS5045.......................................................................................................................................................... www.austriamicrosystems.com/AS5245 Revision 1.3 25 25 27 27 28 28 28 28 29 2 - 33 AS5245 Data Sheet - C o n t e n t s 10 Package Drawings and Markings ......................................................................................................................................... 30 11 Ordering Information ............................................................................................................................................................. 32 www.austriamicrosystems.com/AS5245 Revision 1.3 3 - 33 AS5245 Data Sheet - P i n A s s i g n m e n t s 4 Pin Assignments VDD3V_Top VDDA5V_Bottom VDDA5V_Top MagINCn_Top MagINCn_Bottom MagDECn_Top MagDECn_Bottom DTest1_A_Top Figure 2. Pin Assignments (Top View) 32 31 30 29 28 27 26 25 DTest1_A_Bottom 1 24 VDD3V_Bottom DTest2_B_Top 2 23 NC DTest2_B_Bottom 3 22 NC NC 4 21 NC NC 5 20 NC Mode_Index_Top 6 19 PWM_Top Mode_Index_Bottom 7 18 PWM_Bottom VSS_Top 8 17 CSn_Top www.austriamicrosystems.com/AS5245 Revision 1.3 CSn_Bottom DO_Bottom DO_Top CLK_Bottom PDIO_Top CLK_Top 10 11 12 13 14 15 16 PDIO_Bottom 9 VSS_Bottom AS5245 4 - 33 AS5245 Data Sheet - P i n A s s i g n m e n t s 4.1 Pin Descriptions Table 1. Pin Descriptions Pin Name Pin Number Pin Type DTest1_A 1, 32 Digital output Test output in default mode DTest2_B 2, 3 Digital output Test output in default mode NC 4, 5 - Mode_Index 6, 7 Digital I/O pull-down VSS 8, 9 Supply pin PDIO 10, 11 OTP Programming Input and Data Input for Daisy Chain mode. Digital input pull-down Internal pull-down resistor (~74k). Should be connected to VSS if programming is not used. CLK 12, 13 Digital input, Schmitt- Clock Input of Synchronous Serial Interface; Schmitt-Trigger input trigger input DO 14, 15 CSn 16, 17 PWM 18, 19 Digital output NC 20, 21 - For internal use. Must be left unconnected NC 22, 23 - For internal use. Must be left unconnected VDD3V3 24, 25 Supply pin 3V-Regulator Output for internal core, regulated from VDD5V. Connect to VDD5V for 3V supply voltage. Do not load externally. VDD5V 26, 27 Supply pin Positive Supply Voltage, 3.0V to 5.5V MagINCn 28, 29 Digital output open drain Magnet Field Magnitude Increase. Active low. Indicates a distance reduction between the magnet and the device surface. MagDECn 30, 31 Digital output open drain Magnet Field Magnitude Decrease. Active low. Indicates a distance increase between the device and the magnet. www.austriamicrosystems.com/AS5245 Digital output / tristate Description For internal use. Must be left unconnected Select between slow (open, low: VSS) and fast (high) mode. Internal pulldown resistor. Negative Supply Voltage (GND) Data Output of Synchronous Serial Interface Digital input pull-up, Chip Select. Active low. Schmitt-Trigger input, internal pull-up resistor Schmitt-trigger input (~50k) Pulse Width Modulation of approx. 244Hz; 1s/step (opt. 122Hz; 2s/ step) Revision 1.3 5 - 33 AS5245 Data Sheet - A b s o l u t e M a x i m u m R a t i n g s 5 Absolute Maximum Ratings Stresses beyond those listed in Table 2 may cause permanent damage to the device. These are stress ratings only, and functional operation of the device at these or any other conditions beyond those indicated in Electrical Characteristics on page 7 is not implied. Exposure to absolute maximum rating conditions for extended periods may affect device reliability. Table 2. Absolute Maximum Ratings Parameter Min Max Units DC supply voltage at pin VDD5V -0.3 7 V DC supply voltage at pin VDD3V3 -0.3 5 V Comments Input pin voltage -0.3 7 V Pins Prog, MagINCn, MagDECn, CLK, CSn Input current (latchup immunity) -100 100 mA Norm: JEDEC 78 2 kV Norm: MIL 883 E method 3015 +150 C 260 C Electrostatic discharge Storage temperature -55 Body temperature (Lead-free package) Humidity non-condensing 5 85 % Ambient temperature -40 150 C www.austriamicrosystems.com/AS5245 Revision 1.3 t=20 to 40s, Norm: IPC/JEDEC J-Std-020C Lead finish 100% Sn "matte tin" 6 - 33 AS5245 Data Sheet - E l e c t r i c a l C h a r a c t e r i s t i c s 6 Electrical Characteristics TAMB = -40 to +150C, VDD5V = 3.0-3.6V (3V operation) VDD5V = 4.5-5.5V (5V operation) unless otherwise noted. Table 3. Electrical Characteristics Symbol Parameter Condition Min Typ Max Unit +150 C 16 21 mA 4.5 5.0 5.5 3.0 3.3 3.6 3.0 3.3 3.6 3.0 3.3 3.6 1.37 2.2 2.9 1.08 1.9 2.6 Operating Conditions TAMB Ambient temperature Isupp Supply current VDD5V Supply voltage at pin VDD5V -40 (one die only) VDD3V3 Voltage regulator output voltage at pin VDD3V3 5V Operation VDD5V Supply voltage at pin VDD5V VDD3V3 Supply voltage at pin VDD3V3 3.3V Operation (pin VDD5V and VDD3V3 connected) VON Power-on reset thresholds On voltage; 300mV typ. hysteresis VOFF Power-on reset thresholds Off voltage; 300mV typ. hysteresis DC supply voltage 3.3V (VDD3V3) V V V Programming Conditions VPROG Programming voltage Voltage applied during programming 3.3 3.6 V VProgOff Programming voltage off level Line must be discharged to this level 0 1 V IPROG Programming current Current during programming 100 mA Rprogrammed Programmed fuse resistance (log 1) 10A maximum current@100mV 100k Runprogrammed Unprogrammed fuse resistance (log 0) 2mA maximum current@100mV 50 100 DC Characteristics CMOS Schmitt-Trigger Inputs: CLK, CSn (CSn = Internal Pull-up) Normal operation 0.7 * VDD5V VIH High level input voltage V VIL Low level input voltage VIon- VIoff Schmitt Trigger hysteresis ILEAK Input leakage current CLK only -1 1 IiL Pull-up low level input current CSn only, VDD5V: 5.0V -30 -100 0.7 * VDD5V VDD5V V 3.3 3.6 V 0.3 * VDD5V V 100 A 0.3 * VDD5V 1 V V A DC Characteristics CMOS / Program Input: PDIO VIH High level input voltage VPROG High level input voltage VIL Low level input voltage IiL High level input current During programming, Either with 3.3V or 5V supply VDD5V: 5.5V 30 DC Characteristics CMOS Output Open Drain: MagINCn, MagDECn IOZ Open drain leakage current 1 A VOL Low level output voltage VSS +0.4 V www.austriamicrosystems.com/AS5245 Revision 1.3 7 - 33 AS5245 Data Sheet - E l e c t r i c a l C h a r a c t e r i s t i c s Table 3. Electrical Characteristics Symbol Parameter IO Output current Condition Min Typ Max VDD5V: 4.5V 4 VDD5V: 3V 2 Unit mA DC Characteristics CMOS Output: PWM VOH High level output voltage VOL Low level output voltage IO Output current VDD5V- 0.5 V VSS +0.4 VDD5V: 4.5V 4 VDD5V: 3V 2 V mA DC Characteristics CMOS Output: A, B, Index VOH High level output voltage VOL Low level output voltage IO Output current VDD5V- 0.5 V VSS +0.4 VDD5V: 4.5V 4 VDD5V: 3V 2 V mA DC Characteristics Tri-state CMOS Output: DO VOH High level output voltage VOL Low level output voltage IO Output current IOZ Tri-state leakage current VDD5V- 0.5 V VSS +0.4 VDD5V: 4.5V 4 VDD5V: 3V 2 V mA 1 A 6.1 Magnetic Input Specification TAMB = -40 to +150C, VDD5V = 3.0 to 3.6V (3V operation) VDD5V = 4.5 to 5.5V (5V operation) unless otherwise noted. Two-pole cylindrical diametrically magnetized source: Table 4. Magnetic Input Specification Symbol Parameter Condition Min Typ dmag Diameter 4 6 tmag Thickness Recommended magnet: O 6mm x 2.5mm for cylindrical magnets Bpk Magnetic input field amplitude Required vertical component of the magnetic field strength on the die's surface, measured along a concentric circle with a radius of 1.1mm Boff Magnetic offset Field non-linearity fmag_abs Input frequency (rotational speed of magnet) Max mm 2.5 45 Unit mm 75 mT Constant magnetic stray field 10 mT Including offset gradient 5 % 153 rpm @ 4096 positions/rev; fast mode 2.54 38 rpm @ 4096 positions/rev; slow mode 0.63 Hz Disp Displacement radius Maximum offset between defined device center and magnet axis 0.25 mm Ecc Eccentricity Eccentricity of magnet center to rotational axis 100 m www.austriamicrosystems.com/AS5245 Revision 1.3 8 - 33 AS5245 Data Sheet - E l e c t r i c a l C h a r a c t e r i s t i c s Table 4. Magnetic Input Specification Symbol Parameter Condition Min Typ Recommended magnet material and temperature drift NdFeB (Neodymium Iron Boron) -0.12 SmCo (Samarium Cobalt) -0.035 Max Unit %/K 6.2 System Specifications TAMB = -40 to +150C, VDD5V = 3.0 to3.6V (3V operation) VDD5V = 4.5 to5.5V (5V operation) unless otherwise noted. Table 5. Input Specification Symbol Parameter Condition RES Resolution INLopt INLtemp Max Unit 0.088 deg 12 bit Integral non-linearity (optimum) Maximum error with respect to the best line fit. Centered magnet without calibration, TAMB =25C. 0.5 deg Integral non-linearity (optimum) Maximum error with respect to the best line fit. Centered magnet without calibration, TAMB = -40 to +150C 0.9 deg INL Integral non-linearity Best line fit = (Errmax - Errmin) / 2 Over displacement tolerance with 6mm diameter magnet, without calibration, TAMB = 40 to +150C 1.4 deg DNL Differential non-linearity 12bit, no missing codes 0.044 deg 1 sigma, fast mode (MODE = 1) 0.06 TN Transition noise 1 sigma, slow mode (MODE = 0 or open) 0.03 Fast mode (Mode = 1); Until status bit OCF = 1 20 Slow mode (Mode = 0 or open); Until OCF = 1 80 Fast mode (MODE = 1) 96 Slow mode (MODE = 0 or open) 384 tPwrUp tdelay fS fS CLK/SEL Power-up time System propagation delay absolute output : delay of ADC, DSP and absolute interface Internal sampling rate for absolute output: Internal sampling rate for absolute output Read-out frequency www.austriamicrosystems.com/AS5245 Min Typ ms TAMB = 25C, slow mode (MODE=0 or open) 2.48 2.61 2.74 TAMB = -40 to +150C, slow mode (MODE=0 or open) 2.35 2.61 2.87 TAMB = 25C, fast mode (MODE = 1) 9.90 10.42 10.94 TAMB = -40 to +150C, fast mode (MODE=1) 9.38 10.42 11.46 Maximum clock frequency to read out serial data Revision 1.3 Deg RMS s kHz kHz 1 MHz 9 - 33 AS5245 Data Sheet - E l e c t r i c a l C h a r a c t e r i s t i c s Figure 3. Integral and Differential Non-Linearity Example 1023 10bit code 1023 Actual curve 2 TN DNL+1LSB 1 0 Ideal curve INL 0.35 512 512 0 0 180 360 [degrees] Integral Non-Linearity (INL) is the maximum deviation between actual position and indicated position. Differential Non-Linearity (DNL) is the maximum deviation of the step length from one position to the next. Transition Noise (TN) is the repeatability of an indicated position. www.austriamicrosystems.com/AS5245 Revision 1.3 10 - 33 AS5245 Data Sheet - T i m i n g C h a r a c t e r i s t i c s 7 Timing Characteristics TAMB= -40 to +150C, VDD5V= 3.0 to 3.6V (3V operation) VDD5V= 4.5 to 5.5V (5V operation), unless otherwise noted. Table 6. Timing Characteristics Symbol Parameter Conditions Min Typ Max Units 100 ns Synchronous Serial Interface (SSI) tDOactive Data output activated (logic high) Time between falling edge of CSn and data output activated tCLKFE First data shifted to output register Time between falling edge of CSn and first falling edge of CLK 500 ns TCLK/2 Start of data output Rising edge of CLK shifts out one bit at a time 500 ns tDOvalid Data output valid Time between rising edge of CLK and data output valid 413 ns tDOtristate Data output tri-state After the last bit DO changes back to "tristate" 100 ns tCSn Pulse width of CSn CSn =high; To initiate read-out of next angular position 500 fCLK Read-out frequency Clock frequency to read out serial data >0 ns 1 MHz Pulse Width Modulation Output fPWM PWM frequency Signal period = 4098s 10% at TAMB = -40 to +150C 220 224 268 Hz PWMIN Minimum pulse width Position 0d; angle 0 degree 0.90 1 1.10 s PWMAX Maximum pulse width Position 4098d; angle 359.91 degrees 3686 4096 4506 s tPROG Programming time per bit Time to prog. a singe fuse bit 10 20 s tCHARGE Refresh time per bit Time to charge the cap after tPROG 1 fLOAD LOAD frequency Data can be loaded at n x 2s 500 kHz fREAD READ frequency Read the data from the latch 2.5 MHz fWRITE WRITE frequency Write the data to the latch 2.5 MHz Programming Conditions www.austriamicrosystems.com/AS5245 Revision 1.3 s 11 - 33 AS5245 Data Sheet - D e t a i l e d D e s c r i p t i o n 8 Detailed Description The AS5245 is manufactured in a CMOS standard process and uses a spinning current Hall technology for sensing the magnetic field distribution across the surface of the chip. The integrated Hall elements are placed around the center of the device and deliver a voltage representation of the magnetic field at the surface of the IC. Through Sigma-Delta Analog / Digital Conversion and Digital Signal-Processing (DSP) algorithms, the AS5245 provides accurate high-resolution absolute angular position information. For this purpose, a Coordinate Rotation Digital Computer (CORDIC) calculates the angle and the magnitude of the Hall array signals. The DSP is also used to provide digital information at the outputs MagINCn and MagDECn that indicate movements of the used magnet towards or away from the device's surface. A small low cost diametrically magnetized (two-pole) standard magnet provides the angular position information (see Figure 16). The AS5245 senses the orientation of the magnetic field and calculates a 12-bit binary code. This code can be accessed via. a Synchronous Serial Interface (SSI). In addition, an absolute angular representation is given by a Pulse Width Modulated signal at pin 12 (PWM). This PWM signal output also allows the generation of a direct proportional analog voltage, by using an external Low-Pass-Filter. The AS5245 is tolerant to magnet misalignment and magnetic stray fields due to differential measurement technique and Hall sensor conditioning circuitry. Figure 4. Typical Arrangement of AS5245 and Magnet 8.1 Mode_Index Pin The Mode_Index pin activates or deactivates an internal filter that is used to reduce the analog output noise. Activating the filter (Mode pin = LOW or open) provides a reduced output noise of 0.03 rms. At the same time, the output delay is increased to 384s. This mode is recommended for high precision, low speed applications. Deactivating the filter (Mode pin = HIGH) reduces the output delay to 96s and provides an output noise of 0.06 rms. This mode is recommended for higher speed applications. Setting up the Mode pin affects the following parameters: Table 7. Slow and Fast Mode Parameters Parameter Slow Mode (mode=low or open) Fast Mode (mode=high, VDD=5V) Sampling rate 2.61 kHz (384 s) 10.42 kHz (96s) Transition noise (1 sigma) 0.03 rms 0.06 rms Output delay 384s 96s Maximum speed @ 4096 samples/rev 38 rpm 153 rpm Maximum speed @ 1024 samples/rev 153 rpm 610 rpm Maximum speed @ 256 samples/rev 610 rpm 2441 rpm Maximum speed @ 64 samples/rev 2441 rpm 9766 rpm Note: A change of the Mode during operation is not allowed. The setup must be constant during power up and during operation. www.austriamicrosystems.com/AS5245 Revision 1.3 12 - 33 AS5245 Data Sheet - D e t a i l e d D e s c r i p t i o n 8.2 Synchronous Serial Interface (SSI) Figure 5. Synchronous Serial Interface with Absolute Angular Position Data tCLKFE CSn TCLK/2 tCLKFE tCSn 1 CLK DO D11 8 D10 D9 D8 D7 D6 D5 D4 D3 D2 D1 D0 OCF COF Mag Mag LIN INC DEC tDO valid tDO active 1 18 Even PAR D11 tDO Tristate Angular Position Data Status Bits If CSn changes to logic low, Data Out (DO) will change from high impedance (tri-state) to logic high and the read-out will be initiated. After a minimum time tCLK FE, data is latched into the output shift register with the first falling edge of CLK. Each subsequent rising CLK edge shifts out one bit of data. The serial word contains 18 bits, the first 12 bits are the angular information D[11:0], the subsequent 6 bits contain system information, about the validity of data such as OCF, COF, LIN, Parity and Magnetic Field status (increase/decrease). A subsequent measurement is initiated by a "high" pulse at CSn with a minimum duration of tCSn. 8.2.1 Serial Data Contents D11:D0 - Absolute angular position data (MSB is clocked out first). OCF - (Offset Compensation Finished). Logic high indicates the finished Offset Compensation Algorithm. COF - (Cordic Overflow). Logic high indicates an out of range error in the CORDIC part. When this bit is set, the data at D9:D0 is invalid. The absolute output maintains the last valid angular value. This alarm may be resolved by bringing the magnet within the X-Y-Z tolerance limits. LIN - (Linearity Alarm). Logic high indicates that the input field generates a critical output linearity. When this bit is set, the data at D9:D0 may still be used, but can contain invalid data. This warning may be resolved by bringing the magnet within the X-Y-Z tolerance limits. Even Parity - Bit for transmission error detection of bits 1...17 (D11...D0, OCF, COF, LIN, MagINC, MagDEC). Placing the magnet above the chip, angular values increase in clockwise direction by default. Data D11:D0 is valid, when the status bits have the following configurations: Table 8. Status Bit Outputs OCF 1 COF 0 LIN Mag INC Mag DEC 0 0 0 1 1 0 1 1 0 Parity Even checksum of bits 1:15 Note: MagInc=MagDec=1 is only recommended in YELLOW mode (see Table 9) www.austriamicrosystems.com/AS5245 Revision 1.3 13 - 33 AS5245 Data Sheet - D e t a i l e d D e s c r i p t i o n 8.2.2 Z-axis Range Indication (Push Button Feature, Red/Yellow/Green Indicator) The AS5245 provides several options of detecting movement and distance of the magnet in the Z-direction. Signal indicators MagINCn and MagDECn are available both as hardware pins (pins #1 and 2) and as status bits in the serial data stream (see Figure 5). Additionally, an OTP programming option is available with bit MagCompEn that enables additional features: In the default state, the status bits MagINC, MagDec and pins MagINCn, MagDECn have the following function: Table 9. Magnetic Field Strength Red-Yellow-Green Indicator (OTP option) Status Bits Hardware Pins OPT: Mag CompEn = 1 (Red-Yellow-Green Programming Option) Mag INC Mag DEC LIN Mag INCn Mag DECn 0 0 0 Off Off No distance change Magnetic input field OK (GREEN range, ~45...75mT) 1 1 0 On Off YELLOW range: magnetic field is ~ 25...45mT or ~75...135mT. The AS5245 may still be operated in this range, but with slightly reduced accuracy. 1 1 1 On On RED range: magnetic field is ~<25mT or >~135mT. It is still possible to operate the AS5245 in the red range, but not recommended. n/a n/a Not available All other combinations Description Note: Pin 1 (MagINCn) and pin 2 (MagDECn) are active low via. open drain output and require an external pull-up resistor. If the magnetic field is in range, both outputs are turned off. The two pins may also be combined with a single pull-up resistor. In this case, the signal is high when the magnetic field is in range. It is low in all other cases (see Table 9). 8.2.3 Incremental Mode The AS5245 has an internal interpolator block. This function is used if the input magnetic field is too fast and a code position is missing. In this case an interpolation is done. With the OTP bits OutputMd0 and OutputMd1 a specific mode can be selected. For the available pre-programmed incremental versions (10bit and 12bit), these bits are set during test at austriamicrosystems. These settings are permanent and can not be recovered. A change of the incremental mode (WRITE command) during operation could cause problems. A power-on-reset in between is recommended. During operation in incremental mode it is recommended setting CSn = High, to disable the SSI-Interface. Table 10. Incremental Resolution Mode Description Output Md1 Default mode AS5245 function DTEST1_A and DTEST2_B are not used. The Mode_Index pin is used for selection of the decimation rate (low speed/high speed). 0 0 0 1 10 bit Incremental mode (low DNL) 12 bit Incremental mode (high DNL) Sync mode Output Md0 DTEST1_A and DTEST2_B are used as A and B signal. In this mode the Mode_Index Pin is switched from input to output and will be the Index Pin. The decimation rate is set to 64 (fast mode) and cannot be changed from external. 1 0 In this mode a control signal is switched to DTEST1_A and DTEST2_B. 1 1 www.austriamicrosystems.com/AS5245 Resolution DTest1_A and DTest2_B Pulses 10 256 Index Width 1/3 LSB Revision 1.3 12 1024 14 - 33 AS5245 Data Sheet - D e t a i l e d D e s c r i p t i o n Figure 6. Incremental Output Programmed Zero Position ClockWise Counter ClockWise D Test1_A D Test2_B 1 LSB Mode_Index 3 LSB The hysteresis trimming is done at the final test (factory trimming) and set to 4 LSB, related to a 12 bit number. Incremental Output Hysteresis. To avoid flickering incremental outputs at a stationary magnet position, a hysteresis is introduced. In case of a rotational direction change, the incremental outputs have a hysteresis of 4 LSB. Regardless of the programmed incremental resolution, the hysteresis of 4 LSB always corresponds to the highest resolution of 12 bit. In absolute terms, the hysteresis is set to 0.35 degrees for all resolutions. For constant rotational directions, every magnet position change is indicated at the incremental outputs (see Figure 7). For example, if the magnet turns clockwise from position "x+3" to "x+4", the incremental output would also indicate this position accordingly. A change of the magnet's rotational direction back to position "x+3" means that the incremental output still remains unchanged for the duration of 4 LSB, until position "x+2"is reached. Following this direction, the incremental outputs will again be updated with every change of the magnet position. Figure 7. Hysteresis Window for Incremental Outputs Incremental Output Indication Hysteresis : 0.35 X +6 X +5 X +4 X +3 X +2 X +1 X X X +1 X +2 X +3 X +4 X +5 X +6 Magnet Position Clockwise Direction Counterclockwise Direction www.austriamicrosystems.com/AS5245 Revision 1.3 15 - 33 AS5245 Data Sheet - D e t a i l e d D e s c r i p t i o n Incremental Output Validity. During power on the incremental output is kept stable high until the offset compensation is finished and the CSn is low (internal Pull Up) the first time. In quadrature mode A = B = Index = high indicates an invalid output. If the interpolator recognizes a difference larger than 128 steps between two samples, it holds the last valid state. The interpolator synchronizes up again with the next valid difference. This avoids undefined output burst, e.g. if no magnet is present. 8.2.4 Sync Mode This mode is used to synchronize the external electronic with the AS5245. In this mode, two signals are provided at the pins DTEST1_A and DTEST2_B. By setting of Md0=1 and Md1=1 in the OTP register, the Sync mode will be activated. Figure 8. DTest1_A and DTest2_B 400s (100s) DTest1_A DTest1_B Every rising edge at DTEST1_A indicates that new data in the device is available. With this signal it is possible to trigger an external customer Microcontroller (interrupt) and start the SSI readout. DTEST2_B indicates the phase of available data. 8.2.5 Sine/Cosine Mode This mode can be enabled by setting the OTP Factory-bit FS2. If this mode is activated, the 16 bit sinus and 16 bit cosines digital data of both channels will be switched out. Due to the high resolution of 16 bits of the data stream, an accurate calculation can be done externally. In this mode, the open drain outputs of DTEST1_A and DTEST2_B are switched to push-pull mode. At Pin MagDECn the clock impulse, at Pin MagINCn the Enable pulse will be switched out. The pin PWM indicates, which phase of signal is being presented. The mode is not available in the default mode. 8.2.6 Daisy Chain Mode The Daisy Chain mode allows connection of several AS5245s in series, while still keeping just one digital input for data transfer (see "Data IN" in Figure 9). This mode is accomplished by connecting the data output (DO; pin 9) to the data input (PDIO; pin 8) of the subsequent device. The serial data of all connected devices is read from the DO pin of the first device in the chain. The length of the serial bit stream increases with every connected device, it is n * (18+1) bits: n= number of devices. E.g. 38 bit for two devices, 57 bit for three devices, etc. The last data bit of the first device (Parity) is followed by a dummy bit and the first data bit of the second device (D11), etc. (see Figure 10). Figure 9. Daisy Chain Hardware Configuration AS5145 AS5145 C st 1 Device Data IN DO CSn PDIO CLK 2 nd DO CSn Device PDIO CLK AS5145 last Device DO CSn PDIO CLK CLK CSn www.austriamicrosystems.com/AS5245 Revision 1.3 16 - 33 AS5245 Data Sheet - D e t a i l e d D e s c r i p t i o n Figure 10. Daisy Chain Mode Data Transfer CSn TCLK/2 tCLK FE 1 CLK 8 D11 D10 D9 DO D8 D7 D6 D5 D4 18 D3 D2 D1 D0 OCF COF LIN Mag Mag Even INC DEC PAR D 1 2 3 D11 D10 D9 tDO valid Angular Position Data tDO active Status Bits Angular Position Data nd 2 Device st 1 Device 8.3 Pulse Width Modulation (PWM) Output The AS5245 provides a pulse width modulated output (PWM), whose duty cycle is proportional to the measured angle. For angle position 0 to 4094: t on 4098 Position = ------------------------- - 1 ( t on + t off ) (EQ 1) Examples: 1. An angle position of 180 will generate a pulse width ton = 2049s and a pause tOFF of 2049 s resulting in Position = 2048 after the calculation: 2049 * 4098 / (2049 + 2049) -1 = 2048 2. An angle position of 359.8 will generate a pulse width ton = 4095s and a pause tOFF of 3 s resulting in Position = 4094 after the calculation: 4095 * 4098 / (4095 + 3) -1 = 4094 Exception: 1. An angle position of 359.9 will generate a pulse width ton = 4097s and a pause tOFF of 1 s resulting in Position = 4096 after the calculation: 4097 * 4098 / (4097 + 1) -1 = 4096 The PWM frequency is internally trimmed to an accuracy of 5% (10% over full temperature range). This tolerance can be cancelled by measuring the complete duty cycle as shown above. Figure 11. PWM Output Signal Angle PWMIN 0 deg (Pos 0) 1s 4097s PWMAX 359.91 deg (Pos 4095) 4096s 1/fPWM www.austriamicrosystems.com/AS5245 Revision 1.3 17 - 33 AS5245 Data Sheet - D e t a i l e d D e s c r i p t i o n 8.3.1 Changing the PWM Frequency The PWM frequency of the AS5245 can be divided by two by setting a bit (PWMhalfEN) in the OTP register (see Programming the AS5245 on page 19). With PWMhalfEN = 0, the PWM timing is as shown in Table 11: Table 11. PWM Signal Parameters (default mode) Symbol Parameter Typ Unit Note fPWM PWM frequency 244 Hz Signal period: 4097s PWMIN MIN pulse width 1 s - Position 0d - Angle 0 deg PWMAX MAX pulse width 4096 s - Position 4095d - Angle 359,91 deg When PWMhalfEN = 1, the PWM timing is as shown in Table 12: Table 12. PWM Signal Parameters with Half Frequency (OTP option) Symbol Parameter Typ Unit Note fPWM PWM frequency 2 s - Position 0d - Angle 0 deg PWMIN MIN pulse width 8192 s - Position 4095d - Angle 359,91 deg PWMAX MAX pulse width 2 s - Position 0d - Angle 0 deg 8.4 Analog Output An analog output can be generated by averaging the PWM signal, using an external active or passive low pass filter. The analog output voltage is proportional to the angle: 0= 0V; 360 = VDD5V. Using this method, the AS5245 can be used as direct replacement of potentiometers. Figure 12. Simple 2nd Order Passive RC Low Pass Filter Pin12 R2 R1 analog out PWM VDD C1 C2 0V Pin7 0 360 VSS Figure 12 shows an example of a simple passive low pass filter to generate the analog output. R1,R2 4k7 C1,C2 1F / 6V (EQ 2) R1 should be greater than or equal to 4k7 to avoid loading of the PWM output. Larger values of Rx and Cx will provide better filtering and less ripple, but will also slow down the response time. www.austriamicrosystems.com/AS5245 Revision 1.3 18 - 33 AS5245 Data Sheet - A p p l i c a t i o n I n f o r m a t i o n 9 Application Information The benefits of AS5245 are as follows: Complete system-on-chip Angle measurement with programmable range up to 360 High reliability due to non-contact magnetic sensing Ideal for applications in harsh environments Robust system, tolerant to magnet misalignment, airgap variations, temperature variations and external magnetic fields No calibration required Building of redundancy systems with plausibility checks 9.1 Programming the AS5245 After power-on, programming the AS5245 is enabled with the rising edge of CSn with PDIO = high and CLK = low. The AS5245 programming is a one-time programming (OTP) method, based on poly silicon fuses. The advantage of this method is that a programming voltage of only 3.3V to 3.6V is required for programming. The OTP consists of 52 bits, of which 21 bits are available for user programming. The remaining 31 bits contain factory settings and a unique chip identifier (Chip-ID). A single OTP cell can be programmed only once. Per default, the cell is "0"; a programmed cell will contain a "1". While it is not possible to reset a programmed bit from "1" to "0", multiple OTP writes are possible, as long as only unprogrammed "0"-bits are programmed to "1". Independent of the OTP programming, it is possible to overwrite the OTP register temporarily with an OTP write command at any time. This setting will be cleared and overwritten with the hard programmed OTP settings at each power-up sequence or by a LOAD operation. Use application note AN514X_10 to get more information about the programming options. The OTP memory can be accessed in the following ways: Load Operation: The Load operation reads the OTP fuses and loads the contents into the OTP register. A Load operation is automatically executed after each power-on-reset. Write Operation: The Write operation allows a temporary modification of the OTP register. It does not program the OTP. This operation can be invoked multiple times and will remain set while the chip is supplied with power and while the OTP register is not modified with another Write or Load operation. Read Operation: The Read operation reads the contents of the OTP register, for example to verify a Write command or to read the OTP memory after a Load command. Program Operation: The Program operation writes the contents of the OTP register permanently into the OTP ROM. Analog Readback Operation: The Analog Readback operation allows a quantifiable verification of the programming. For each programmed or unprogrammed bit, there is a representative analog value (in essence, a resistor value) that is read to verify whether a bit has been successfully programmed or not. 9.1.1 Zero Position Programming Zero position programming is an OTP option that simplifies assembly of a system, as the magnet does not need to be manually adjusted to the mechanical zero position. Once the assembly is completed, the mechanical and electrical zero positions can be matched by software. Any position within a full turn can be defined as the permanent new zero position. For zero position programming, the magnet is turned to the mechanical zero position (e.g. the "off"-position of a rotary switch) and the actual angular value is read. This value is written into the OTP register bits Z35:Z46. Note: The zero position value may also be modified before programming, e.g. to program an electrical zero position that is 180 (half turn) from the mechanical zero position, just add 2048 to the value read at the mechanical zero position and program the new value into the OTP register. www.austriamicrosystems.com/AS5245 Revision 1.3 19 - 33 AS5245 Data Sheet - A p p l i c a t i o n I n f o r m a t i o n 9.1.2 OTP Memory Assignment Symbol Function mbit1 Factory Bit 1 51 PWMhalfEN_Index width PMW frequency Index pulse width 50 MagCompEn Alarm mode 49 pwmDIS Disable PWM 48 Output Md0 Default, 10 bit inc, 12 bit inc 47 Output Md1 Sync mode 46 Z0 : : 35 Z11 34 CCW 33 RA0 : : 29 RA4 28 FS 0 27 FS 1 26 FS 2 25 FS 3 24 FS 4 23 FS 5 : : 20 FS 9 17 ChipID0 16 ChipID1 : : 0 ChipID17 12 bit Zero Position Direction Factory Bit 18 bit Chip ID mbit0 9.1.3 Factory Section Redundancy Address ID Section Bit Customer Section Table 13. OTP Bit Assignment Factory Bit 0 User Selectable Settings The AS5245 allows programming of the following user selectable options: - PWMhalfEN_Indexwidth: Setting this bit, the PWM pulse will be divided by 2, in case of quadrature incremental mode A/B/Index setting of Index impulse width from 1 LSB to 3LSB. - MagCompEN: The green/yellow mode can be enabled by setting of this bit. - Output Md0: Setting this bit enables sync- or 10bit incremental mode (see Table 10) - Output Md1: Setting this bit enables sync- or 12bit incremental mode (see Table 10) - Z [11:0]: Programmable Zero / Index Position - CCW: Counter Clockwise Bit ccw=0 - angular value increases in clockwise direction ccw=1 - angular value increases in counterclockwise direction - RA [4:0]: Redundant Address: an OTP bit location addressed by this address is always set to "1" independent of the corresponding original OTP bit setting www.austriamicrosystems.com/AS5245 Revision 1.3 20 - 33 AS5245 Data Sheet - A p p l i c a t i o n I n f o r m a t i o n 9.1.4 OTP Default Setting The AS5245 can also be operated without programming. The default, un-programmed setting is: - 9.1.5 Output Md0, Output MD1: 00= Default mode Z0 to Z11: 00 = no programmed zero position CCW: 0 = clockwise operation RA4 to RA0:0 = no OTP bit is selected MagCompEN: 1 = The green / yellow mode is enabled. Redundancy For a better programming reliability, a redundancy is implemented. This function can be used in cases where the programming of one bit fails. With an address RA(4:0), one bit can be selected and programmed. pwmDIS 0 0 0 00001 1 0 0 0 00010 0 1 0 00011 0 0 1 00100 0 0 00101 0 0 Output Md1 MagCompEN 00000 Output Md0 Address PWMhalfEN_Indexwidth Table 14. Redundancy Addressing Z0 Z1 Z2 Z3 Z4 Z5 Z6 Z7 Z8 Z9 Z10 Z11 CCW 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 0 0 0 0 0 0 0 0 0 0 0 0 0 00110 0 0 0 0 0 1 0 0 0 0 0 0 0 0 0 0 0 0 00111 0 0 0 0 0 0 1 0 0 0 0 0 0 0 0 0 0 0 01000 0 0 0 0 0 0 0 1 0 0 0 0 0 0 0 0 0 0 01001 0 0 0 0 0 0 0 0 1 0 0 0 0 0 0 0 0 0 01010 0 0 0 0 0 0 0 0 0 1 0 0 0 0 0 0 0 0 01011 0 0 0 0 0 0 0 0 0 0 1 0 0 0 0 0 0 0 01100 0 0 0 0 0 0 0 0 0 0 0 1 0 0 0 0 0 0 01101 0 0 0 0 0 0 0 0 0 0 0 0 1 0 0 0 0 0 01110 0 0 0 0 0 0 0 0 0 0 0 0 0 1 0 0 0 0 01111 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 0 0 0 10000 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 0 0 10001 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 0 10010 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 10101 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 9.1.6 Redundant Programming Option In addition to the regular programming, a redundant programming option is available. This option allows that one selectable OTP bit can be set to "1" (programmed state) by writing the location of that bit into a 5-bit address decoder. This address can be stored in bits RA4...RA0 in the OTP user settings. Example: setting RA4...0 to "00001" will select bit 51 = PWhalfEN_Indexwidth, "00010" selects bit 50 = MagCompEN, "10010" selects bit 34 =CCW, etc. www.austriamicrosystems.com/AS5245 Revision 1.3 21 - 33 AS5245 Data Sheet - A p p l i c a t i o n I n f o r m a t i o n 9.2 Alignment Mode The alignment mode simplifies centering the magnet over the center of the chip to gain maximum accuracy. Alignment mode can be enabled with the falling edge of CSn while PDIO = logic high (see Figure 13). The Data bits D11-D0 of the SSI change to a 12-bit displacement amplitude output. A high value indicates large X or Y displacement, but also higher absolute magnetic field strength. The magnet is properly aligned, when the difference between highest and lowest value over one full turn is at a minimum. Under normal conditions, a properly aligned magnet will result in a reading of less than 128 over a full turn. The MagINCn and MagDECn indicators will be = 1 when the alignment mode reading is < 128. At the same time, both hardware pins MagINCn (#1) and MagDECn (#2) will be pulled to VSS. A properly aligned magnet will therefore produce a MagINCn = MagDECn = 1 signal throughout a full 360 turn of the magnet. Stronger magnets or short gaps between magnet and IC may show values larger than 128. These magnets are still properly aligned as long as the difference between highest and lowest value over one full turn is at a minimum. The Alignment mode can be reset to normal operation by a power-on-reset (disconnect / re-connect power supply) or by a falling edge on CSn with PDIO = low. Figure 13. Enabling the Alignment Mode PDIO CSn 2s min. AlignMode enable Read-out via SSI exit AlignMode Read-out via SSI 2s min. Figure 14. Exiting Alignment Mode PDIO CSn www.austriamicrosystems.com/AS5245 Revision 1.3 22 - 33 AS5245 Data Sheet - A p p l i c a t i o n I n f o r m a t i o n 9.3 3.3V / 5V Operation The AS5245 operates either at 3.3V 10% or at 5V 10%. This is made possible by an internal 3.3V Low-Dropout (LDO) Voltage regulator. The internal supply voltage is always taken from the output of the LDO, meaning that the internal blocks are always operating at 3.3V. For 3.3V operation, the LDO must be bypassed by connecting VDD3V3 with VDD5V (see Figure 15). For 5V operation, the 5V supply is connected to pin VDD5V, while VDD3V3 (LDO output) must be buffered by a 1...10F capacitor, which is supposed to be placed close to the supply pin (see Figure 15). Note: The VDD3V3 output is intended for internal use only. It must not be loaded with an external load. The output voltage of the digital interface I/O's corresponds to the voltage at pin VDD5V, as the I/O buffers are supplied from this pin. Figure 15. Connections for 5V / 3.3V Supply Voltages 5V Operation 3.3V Operation 1... 10F VDD3V3 VDD3V3 100n VDD5V 100n LDO Internal VDD VDD5V LDO Internal VDD DO DO 4.5 - 5.5V VSS I N T E R F A C E PWM + - - + CLK 3.0 - 3.6V CSn PDIO VSS I N T E R F A C E PWM CLK CSn PDIO A buffer capacitor of 100nF is recommended in both cases close to pin VDD5V. Note that pin VDD3V3 must always be buffered by a capacitor. It must not be left floating, as this may cause an instable internal 3.3V supply voltage, which may lead to larger than normal jitter of the measured angle. www.austriamicrosystems.com/AS5245 Revision 1.3 23 - 33 AS5245 Data Sheet - A p p l i c a t i o n I n f o r m a t i o n 9.4 Choosing the Proper Magnet Typically, the magnet should be 6mm in diameter and 2.5mm in height. Magnetic materials such as rare earth AlNiCo/SmCo5 or NdFeB are recommended. The magnetic field strength perpendicular to the die surface has to be in the range of 45mT...75mT (peak). The magnet's field strength should be verified using a gauss-meter. The magnetic field Bv at a given distance, along a concentric circle with a radius of 1.1mm (R1), should be in the range of 45mT...75mT (see Figure 16). Figure 16. Typical Magnet (6x3mm) and Magnetic Field Distribution typ. 6mm diameter N S Magnet axis Magnet axis R1 Vertical field component R1 concentric circle; radius 1.1mm Vertical field component Bv (45...75mT) 0 360 360 www.austriamicrosystems.com/AS5245 Revision 1.3 24 - 33 AS5245 Data Sheet - A p p l i c a t i o n I n f o r m a t i o n 9.5 Failure Diagnostics The AS5245 also offers several diagnostic and failure detection features, which are discussed in detail further in the document. 9.5.1 Magnetic Field Strength Diagnosis By Software: The MagINC and MagDEC status bits will both be high when the magnetic field is out of range. By Hardware: Pins #1 (MagINCn) and #2 (MagDECn) are open-drain outputs and will both be turned on (= low with external pull-up resistor) when the magnetic field is out of range. If only one of the outputs are low, the magnet is either moving towards the chip (MagINCn) or away from the chip (MagDECn). 9.5.2 Power Supply Failure Detection By Software: If the power supply to the AS5245 is interrupted, the digital data read by the SSI will be all "0"s. Data is only valid, when bit OCF is high, hence a data stream with all "0"s is invalid. To ensure adequate low levels in the failure case, a pull-down resistor (~10k) should be added between pin DIO and VSS at the receiving side. By Hardware: The MagINCn and MagDECn pins are open drain outputs and require external pull-up resistors. In normal operation, these pins are high ohmic and the outputs are high (see Table 9). In a failure case, either when the magnetic field is out of range of the power supply is missing, these outputs will become low. To ensure adequate low levels in case of a broken power supply to the AS5245, the pull-up resistors (~10k) from each pin must be connected to the positive supply at pin 16 (VDD5V). By Hardware, PWM Output: The PWM output is a constant stream of pulses with 1kHz repetition frequency. In case of power loss, these pulses are missing. 9.6 Angular Output Tolerances 9.6.1 Accuracy Accuracy is defined as the error between measured angle and actual angle. It is influenced by several factors: The non-linearity of the analog-digital converters, Internal gain and mismatch errors, Non-linearity due to misalignment of the magnet. As a sum of all these errors, the accuracy with centered magnet = (Errmax - Errmin)/2 is specified as better than 0.5 degrees @ 25C (see Figure 19). Misalignment of the magnet further reduces the accuracy. Figure 18 shows an example of a 3D-graph displaying non-linearity over XYmisalignment. The center of the square XY-area corresponds to a centered magnet (see dot in the center of the graph). The X- and Y- axis extends to a misalignment of 1mm in both directions. The total misalignment area of the graph covers a square of 2x2 mm (79x79mil) with a step size of 100m. For each misalignment step, the measurement as shown in Figure 19 is repeated and the accuracy (Errmax - Errmin)/2 (e.g. 0.25 in Figure 19) is entered as the Z-axis in the 3D-graph. www.austriamicrosystems.com/AS5245 Revision 1.3 25 - 33 AS5245 Data Sheet - A p p l i c a t i o n I n f o r m a t i o n Figure 17. Example of Linearity Error Over XY Misalignment 6 5 4 3 800 500 2 200 1 -100 x -1000 -1000 -800 -600 -400 -200 y -700 0 200 -400 400 600 800 1000 0 The maximum non-linearity error on this example is better than 1 degree (inner circle) over a misalignment radius of ~0.7mm. For volume production, the placement tolerance of the IC within the package (0.235mm) must also be taken into account. The total nonlinearity error over process tolerances, temperature and a misalignment circle radius of 0.25mm is specified better than 1.4 degrees. The magnet used for this measurement was a cylindrical NdFeB (Bomatec(R) BMN-35H) magnet with 6mm diameter and 2.5mm in height. www.austriamicrosystems.com/AS5245 Revision 1.3 26 - 33 AS5245 Data Sheet - A p p l i c a t i o n I n f o r m a t i o n Figure 18. Example of Linearity Error Over 360 0.5 0.4 0.3 0.2 transition noise 0.1 Err max 0 -0.1 1 55 109 163 217 271 325 379 433 487 541 595 649 703 757 811 865 919 973 Err min -0.2 -0.3 -0.4 -0.5 9.6.2 Transition Noise Transition noise is defined as the jitter in the transition between two steps. Due to the nature of the measurement principle (Hall sensors + Preamplifier + ADC), there is always a certain degree of noise involved. This transition noise voltage results in an angular transition noise at the 1 outputs. It is specified as 0.06 degrees rms (1 sigma) in fast mode (pin MODE = high) and 0.03 degrees rms (1 sigma) in slow mode (pin MODE = low or open). This is the repeatability of an indicated angle at a given mechanical position. The transition noise has different implications on the type of output that is used: Absolute Output; SSI Interface: The transition noise of the absolute output can be reduced by the user by implementing averaging of readings. An averaging of 4 readings will reduce the transition noise by 6dB or 50%, e.g. from 0.03 rms to 0.015 rms (1 sigma) in slow mode. PWM Interface: If the PWM interface is used as an analog output by adding a low pass filter, the transition noise can be reduced by lowering the cutoff frequency of the filter. If the PWM interface is used as a digital interface with a counter at the receiving side, the transition noise may again be reduced by averaging of readings. Incremental Mode: In incremental mode, the transition noise influences the period, width and phase shift of the output signals A, B and Index. However, the algorithm used to generate the incremental outputs guarantees no missing or additional pulses even at high speeds (up to 30.000 rpm and higher). 9.6.3 High Speed Operation Sampling Rate. The AS5245 samples the angular value at a rate of 2.61k (slow mode) or 10.42k (fast mode, selectable by pin MODE) samples per second. Consequently, the absolute outputs are updated each 384s (96s in fast mode). At a stationary position of the magnet, the sampling rate creates no additional error. Absolute Mode. At a sampling rate of 2.6kHz/10.4kHz, the number of samples (n) per turn for a magnet rotating at high speed can be calculated by, nslowomode = nfastmode = 60 ---------------------------------rpm ( 384 )s (EQ 3) 60 -------------------------rmp 96s (EQ 4) The upper speed limit in slow mode is ~6.000rpm and ~30.000rpm in fast mode. The only restriction at high speed is that there will be fewer samples per revolution as the speed increases (see Table 7). Regardless of the rotational speed, the absolute angular value is always sampled at the highest resolution of 12 bit. 1. Statistically, 1 sigma represents 68.27% of readings; 3 sigma represents 99.73% of readings. www.austriamicrosystems.com/AS5245 Revision 1.3 27 - 33 AS5245 Data Sheet - A p p l i c a t i o n I n f o r m a t i o n Incremental Mode. Incremental encoders are usually required to produce no missing pulses up to several thousand rpms. Therefore, the AS5245 has a built-in interpolator, which ensures that there are no missing pulses at the incremental outputs for rotational speeds of up to 30.000 rpm, even at the highest resolution of 10 bits (512 pulses per revolution). 9.6.4 Propagation Delays The propagation delay is the delay between the time that the sample is taken until it is converted and available as angular data. This delay is 96s in fast mode and 384s in slow mode. Using the SSI interface for absolute data transmission, an additional delay must be considered, caused by the asynchronous sampling (0 ... 1/ fsample) and the time it takes the external control unit to read and process the angular data from the chip (maximum clock rate = 1MHz, number of bits per reading = 18). Angular Error Caused by Propagation Delay. A rotating magnet will cause an angular error caused by the output propagation delay. This error increases linearly with speed: esampling = rpm * 6 * prop.delay (EQ 5) Where: esampling = angular error [] rpm = rotating speed [rpm] prop.delay = propagation delay [seconds] Note: Since the propagation delay is known, it can be automatically compensated by the control unit processing the data from the AS5245. 9.6.5 Internal Timing Tolerance The AS5245 does not require an external ceramic resonator or quartz. All internal clock timings for the AS5245 are generated by an on-chip RC oscillator. This oscillator is factory trimmed to 5% accuracy at room temperature (10% over full temperature range). This tolerance influences the ADC sampling rate and the pulse width of the PWM output: Absolute Output; SSI Interface: A new angular value is updated every 96s (typ) in fast mode and every 384s (typ) in slow mode. PWM Output: A new angular value is updated every 400s (typ). The PWM pulse timings tON and tOFF also have the same tolerance as the internal oscillator. If only the PWM pulse width tON is used to measure the angle, the resulting value also has this timing tolerance. However, this tolerance can be cancelled by measuring both tON and tOFF and calculating the angle from the duty cycle (see Pulse Width Modulation (PWM) Output on page 17). Incremental Mode: In incremental mode, the transition noise influences the period, width and phase shift of the output signals A, B and Index. However, the algorithm used to generate the incremental outputs guarantees no missing or additional pulses even at high speeds (up to 30.000 rpm and higher). t on 4097 Position = ------------------------- - 1 ( t on + t off ) 9.6.6 (EQ 6) Temperature Magnetic Temperature Coefficient. One of the major benefits of the AS5245 compared to linear Hall sensors is that it is much less sensitive to temperature. While linear Hall sensors require a compensation of the magnet's temperature coefficients, the AS5245 automatically compensates for the varying magnetic field strength over temperature. The magnet's temperature drift does not need to be considered, as the AS5245 operates with magnetic field strengths from 45...75mT. Example: A NdFeB magnet has a field strength of 75mT @ -40C and a temperature coefficient of -0.12% per Kelvin. The temperature change is from -40 to +125 = 165K.The magnetic field change is: 165 x -0.12% = -19.8%, which corresponds to 75mT at -40C and 60mT at 125C. The AS5245 can compensate for this temperature related field strength change automatically, no user adjustment is required. 9.6.7 Accuracy over Temperature The influence of temperature in the absolute accuracy is very low. While the accuracy is less than or equal to 0.5 at room temperature, it may increase to less then or equal to 0.9 due to increasing noise at high temperatures. www.austriamicrosystems.com/AS5245 Revision 1.3 28 - 33 AS5245 Data Sheet - A p p l i c a t i o n I n f o r m a t i o n Timing Tolerance over Temperature. The internal RC oscillator is factory trimmed to 5%. Over temperature, this tolerance may increase to 10%. Generally, the timing tolerance has no influence in the accuracy or resolution of the system, as it is used mainly for internal clock generation. The only concern to the user is the width of the PWM output pulse, which relates directly to the timing tolerance of the internal oscillator. This influence, however, can be cancelled by measuring the complete PWM duty cycle instead of just the PWM pulse. 9.7 AS5245 Differences to AS5045 All parameters are according to AS5045 data sheet except for the parameters shown below: Table 15. Difference Between AS5245 and AS5045 Building Block AS5245 AS5045 12bits, 0.088/step. 12bits, 0.088/step. -40C to +150C -40C to +125C Data length read: 18bits (12bits data + 6 bits status) OTP write: 18 bits (12bits zero position + 6 bits mode selection) read: 18bits (12bits data + 6 bits status) OTP write: 18 bits (12bits zero position + 6 bits mode selection) Pins 1 and 2 MagINCn, MagDECn: same feature as AS5045, additional OTP option for red-yellow-green magnetic range MagINCn, MagDECn Resolution Ambient temperature range Incremental encoder Not used Pin3 (DTest1_A); Pin 4 (DTest2_B); Pin 6 (Mode_Index) Pin 3: not used 2x1024 ppr (12-bit) Pin 4:not used 2x256 ppr low-jitter (10-bit) Pin 6 MODE_Index pin selects fast or slow mode in the default configuration. In case of incremental mode, the MODE_Index pin selects fast or slow mode in the fast mode is selected and the pin is configured as default configuration. output. Pin 12 PWM output: frequency selectable by OTP: 1s / step, 4096 steps per revolution, f=244Hz 2s/ step, 4096 steps per revolution, f=122Hz PWM output: frequency selectable by OTP: 1s / step, 4096 steps per revolution, f=244Hz 2s/ step, 4096 steps per revolution, f=122Hz selectable by MODE input pin: 2.5kHz, 10,4kHz selectable by MODE input pin: 2.5kHz, 10,4kHz 384s (slow mode) 384s (slow mode) 96s (fast mode) 96s (fast mode) Sampling frequency Propagation delay Transition noise (rms; 1sigma) OTP programming options 0.03 degrees maximum (slow mode) 0.03 degrees maximum (slow mode) 0.06 degrees maximum (fast mode) 0.06 degrees maximum (fast mode) PPTRIM; programming voltage 3.3V - 3.6V <70C; 3.5V - 3.6V >70C; 52-bit serial data protocol; CSn, PDIO and CLK EasyZap; programming voltage 7.3V - 7.5V; Csn; Prog and CLK; 16-bit (32-bit) serial data protocol; www.austriamicrosystems.com/AS5245 Revision 1.3 29 - 33 AS5245 Data Sheet - P a c k a g e D r a w i n g s a n d M a r k i n g s 10 Package Drawings and Markings The device is available in a QFN 32 (7mm x 7mm) package. Figure 19. Package Drawings AYWWIZZ AS5245 25 32 Top View 24 1 8 17 16 9 Side View Bottom View Table 16. Package Dimensions Symbol mm Min Typ inch Max Min Typ D 7 BSC 0.28 BSC E 7 BSC 0.28 BSC Max D1 4.18 4.28 4.38 0.165 0.169 0.172 E1 4.18 4.28 4.38 0.165 0.169 0.172 L 0.45 0.55 0.65 0.018 0.022 0.026 b 0.25 0.30 0.35 0.010 0.012 0.014 1.00 0.031 0.035 0.039 e A 0.65 BSC 0.80 A1 www.austriamicrosystems.com/AS5245 0.90 0.203 REF 0.008 REF Revision 1.3 30 - 33 AS5245 Data Sheet - R e v i s i o n H i s t o r y Revision History Revision Date Owner Description June 08, 2007 July 24, 2008 Initial revision Changes made to values in Table 10 - Incremental Resolution apg Updated min, typ, max values for tDOvalid parameter in Table 6 - Timing Characteristics Feb 13, 2009 July 15, 2009 1) Note added under Table 7 - Slow and Fast Mode Parameters 2) Output Md0, Md1 description updated, (see User Selectable Settings on page 20) rfu 1.0 Updated values in Table 6 - Timing Characteristics for the following parameters: - tDOvalid - fPWM - PWMIN - PWMAX July 22, 2009 mub 1.1 July 23, 2009 Updated sections Electrical Characteristics on page 7, Timing Characteristics on page 11 and Detailed Description on page 12 according to AS5145 datasheet. Oct 19, 2009 Deleted the following -1) `OTP Programming Connection' figure 2) Physical Placement of the magnet, Magnet Placement, Simulation Modeling apg 1.2 Nov 05, 2009 Timing Characteristics (page 11) - Deleted the parameter `PWM Frequency' (fPWM) 1.3 Dec 04, 2009 Updated section Internal Timing Tolerance (page 28) Note: Typos may not be explicitly mentioned under revision history. www.austriamicrosystems.com/AS5245 Revision 1.3 31 - 33 AS5245 Data Sheet - O r d e r i n g I n f o r m a t i o n 11 Ordering Information The devices are available as the standard products shown in Table 17. Table 17. Ordering Information Ordering Code Description Delivery Form Package AS5245HQFT 12-bit fully redundant magnetic rotary encoder Tape & Reel QFN 32 (7mm x 7mm) Note: All products are RoHS compliant and Pb-free. Buy our products or get free samples online at ICdirect: http://www.austriamicrosystems.com/ICdirect For further information and requests, please contact us mailto:sales@austriamicrosystems.com or find your local distributor at http://www.austriamicrosystems.com/distributor www.austriamicrosystems.com/AS5245 Revision 1.3 32 - 33 AS5245 Data Sheet - C o p y r i g h t s Copyrights Copyright (c) 1997-2009, austriamicrosystems AG, Tobelbaderstrasse 30, 8141 Unterpremstaetten, Austria-Europe. Trademarks Registered (R). All rights reserved. The material herein may not be reproduced, adapted, merged, translated, stored, or used without the prior written consent of the copyright owner. All products and companies mentioned are trademarks or registered trademarks of their respective companies. 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Contact Information Headquarters austriamicrosystems AG Tobelbaderstrasse 30 A-8141 Unterpremstaetten, Austria Tel: +43 (0) 3136 500 0 Fax: +43 (0) 3136 525 01 For Sales Offices, Distributors and Representatives, please visit: http://www.austriamicrosystems.com/contact www.austriamicrosystems.com/AS5245 Revision 1.3 33 - 33