19-1630; Rev 4; 1/11 KIT ATION EVALU E L B AVAILA Low-Cost, Micropower, High-Side Current-Sense Amplifier + Comparator + Reference ICs The MAX4373/MAX4374/MAX4375 low-cost, micropower, high-side current-sense supervisors contain a highside current-sense amplifier, bandgap reference, and comparator with latching output. They feature a voltage output that eliminates the need for gain-setting resistors, making them ideal for today's notebook computers, cell phones, and other systems where battery/DC current monitoring is critical. High-side current monitoring is especially useful in battery-powered systems since it does not interfere with the ground path of the battery charger. The 0 to +28V input common-mode range is independent of the supply voltage, which ensures that the current-sense feedback remains viable even when connected to a battery pack in deep discharge. The comparator output of the MAX4373/MAX4374/ MAX4375 is latched to provide a turn-off flag that doesn't oscillate. In addition, the MAX4374/MAX4375 contain a second comparator for use in window-detection functions. The MAX4373/MAX4374/MAX4375 are available in three different gain versions (T = +20V/V, F = +50V/V, H = +100V/V) and use an external sense resistor to set the sensitivity of the input voltage to the load current. These features offer a high level of integration, resulting in a simple and compact currentsense solution. The MAX4373/MAX4374/MAX4375 operate from a single +2.7V to +28V supply and consume 50A. They are specified for the extended operating temperature range (-40C to +85C) and are available in 8-pin and 10-pin MAX(R) packages. Features Current-Sense Amplifier plus Internal Comparator and Bandgap Reference with Improved Accuracy 50A Supply Current Single +2.7V to +28V Operating Supply 1mV (max) Input Offset Voltage 2% (max) Full-Scale Accuracy Internal Bandgap Reference (1.6% Accuracy) Latching Comparator Output Three Gain Versions Available (+20V/V, +50V/V, +100V/V) High Accuracy +2V to +28V Common-Mode Range, Functional Down to 0V, Independent of Supply Voltage Ordering Information PART TEMP RANGE PINPACKAGE GAIN (V/V) MAX4373TEUA+ -40C to +85C 8 MAX MAX4373TESA+ -40C to +85C 8 SO +20 MAX4373FEUA+ -40C to +85C 8 MAX +50 MAX4373FESA+ -40C to +85C 8 SO +50 MAX4373HEUA+ -40C to +85C 8 MAX +100 +20 MAX4373HESA+ -40C to +85C 8 SO +100 +Denotes a lead(Pb)-free/RoHS-compliant package. Ordering Information continued at end of data sheet. Applications Typical Operating Circuit Notebook Computers Smart Battery Packs/Chargers ILOAD + VSENSE - Portable/Battery-Powered Systems VIN = 0 TO 28V RSENSE Cell Phones Power-Management Systems General-System/Board-Level Current Monitoring Precision Current Sources RS+ VCC = 2.7V TO 28V LOAD/ BATTERY RS- VCC C1 0.1F MAX4373 OUT VPULL-UP (UP TO 5V) R1 R3 CIN COUT MAX is a registered trademark of Maxim Integrated Products, Inc. Pin Configurations appear at end of data sheet. R2 RESET GND ________________________________________________________________ Maxim Integrated Products 1 For pricing, delivery, and ordering information, please contact Maxim Direct at 1-888-629-4642, or visit Maxim's website at www.maxim-ic.com. MAX4373/MAX4374/MAX4375 General Description MAX4373/MAX4374/MAX4375 Low-Cost, Micropower, High-Side Current-Sense Amplifier + Comparator + Reference ICs ABSOLUTE MAXIMUM RATINGS VCC, RS+, RS- to GND ...........................................-0.3V to +30V OUT to GND ................................................-0.3V to the lesser of (VCC + 0.3V) or +15V CIN1, CIN2, RESET to GND ........................-0.3V to the lesser of (VCC + 0.3V) or +12V Differential Input Voltage (VRS+ - VRS-) ..............................0.3V COUT1, COUT2 to GND........................................-0.3V to +6.0V Current into Any Pin..........................................................10mA Continuous Power Dissipation (TA = +70C) 8-Pin MAX (derate 4.1mW/C above +70C) .............330mW 8-Pin SO (derate 5.9mW/C above +70C)..................471mW 10-Pin MAX (derate 5.6mW/C above +70C) ...........444mW 14-Pin SO (derate 8.3mW/C above +70C)................667mW Operating Temperature Range ...........................-40C to +85C Junction Temperature ......................................................+150C Storage Temperature Range .............................-65C to +150C Lead Temperature (soldering, 10s) .................................+300C Soldering Temperature (reflow) .......................................+260C Stresses beyond those listed under "Absolute Maximum Ratings" 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 the operational sections of the specifications is not implied. Exposure to absolute maximum rating conditions for extended periods may affect device reliability. ELECTRICAL CHARACTERISTICS (VCC = +2.7V to +28V, VRS+ = 0 to +28V, VSENSE = 0V, V RESET = 0V, RLOAD= 1M, TA = TMIN to TMAX, unless otherwise noted. Typical values are at TA = +25C.) (Note 1) PARAMETER Operating Voltage Range (Note 2) SYMBOL CONDITIONS MIN TYP MAX UNITS VCC 2.7 28 V Common-Mode Input Range (Note 3) VCMR 0 28 V Common-Mode Rejection CMR Supply Current Leakage Current ICC IRS+ IRS- Input Offset Voltage Total OUT Voltage Error (Note 5) 85 VRS+ > 2V, VSENSE = 5mV 50 100 A 0.015 0.5 A IRS+, IRS- VCC = 0V, VRS+ = 28V Input Bias Current Full-Scale Sense Voltage (Note 4) VRS+ > 2V VSENSE VOS VOUT VRS+ > 2V 0 2.5 VRS+ 2V -25 2.0 VRS+ > 2V 0 4 VRS+ 2V -50 Gain = +20V/V, +50V/V, VRS+ = 12V 150 170 Gain = +100V/V, VRS+ = 12V 100 120 VCC = VRS+ = 12V (Note 11) VSENSE = 100mV (Note 6) TA = +25C VCC = 12V, VRS+ = 12V TA = +25C VCC = 28V, VRS+ = 28V TA = +25C 0.1 0.30 0.35 8.5 VCC VOH VCC = 2.7V, IOUT = -500A, VRS+ = 12V 2 % 5.0 IOUT = 100A OUT Voltage High 2 3 2.5 VCC = 2.7V, VRS+ = 12V mV 5.0 IOUT = 10A VOUT 1 3 TA = TMIN to TMAX OUT Voltage Low mV 2 TA = TMIN to TMAX VSENSE = 6.25mV, VCC = 12V, VRS+ = 12V (Note 7) A 4 TA = TMIN to TMAX VCC = 12V, VRS+ = 0.1V 2 dB _______________________________________________________________________________________ 65 0.25 mV V Low-Cost, Micropower, High-Side Current-Sense Amplifier + Comparator + Reference ICs (VCC = +2.7V to +28V, VRS+ = 0 to +28V, VSENSE = 0V, V RESET = 0V, RLOAD= 1M, TA = TMIN to TMAX, unless otherwise noted. Typical values are at TA = +25C.) (Note 1) PARAMETER -3dB Bandwidth SYMBOL BW CONDITIONS VRS+ = 12V, VCC = 12V, CLOAD = 10pF MIN VSENSE = 100mV, Gain = +20V/V 200 VSENSE = 100mV, Gain = +50V/V 120 VSENSE = 100mV, Gain = +100V/V 110 VSENSE = 6.25mV Gain AV Gain Accuracy AV OUT Settling Time to 1% of Final Value Capacitive Load Stability TYP MAX UNITS kHz 50 MAX437_T +20 MAX437_F +50 MAX437_H +100 VSENSE = 20mV to 150mV; VCC = 12V; VRS+ = 12V; Gain = 20, 50 TA = +25C VSENSE = 20mV to 100mV, VCC = 12V, VRS+ = 12V, Gain = 100 TA = +25C Gain = +20V/V, VCC = 12V, VRS+ = 12V, CLOAD = 10pF VSENSE = 6.25mV to 100mV 20 VSENSE = 100mV to 6.25mV 20 0.3 TA = -40C to +85C V/V 1.7 2.7 % 0.3 TA = -40C to +85C 2.7 s No sustained oscillations OUT Output Resistance ROUT VSENSE = 100mV Power-Supply Rejection PSR VOUT = 2V, VRS+ > 2V 1.7 1000 72 pF 1.5 87 dB Power-Up Time to 1% of Final Value VSENSE = 100mV, CLOAD = 10pF, VCC = 12V, VRS+ = 12V 0.5 ms Saturation Recovery Time (Note 8) VCC = 12V, VRS+ = 12V, CLOAD = 10pF 0.1 ms COMPARATOR (Note 9) Comparator Threshold VTH TA = +25C 590 TA = TMIN to TMAX 586 Comparator Hysteresis Input Bias Current 610 614 -9 IB 2.2 CL = 10pF, RL = 10k pull-up to 5V, 5mV of overdrive Propagation Delay Output Low Voltage 600 VOL ISINK = 1mA mV mV 15 4 nA s 0.6 V _______________________________________________________________________________________ 3 MAX4373/MAX4374/MAX4375 ELECTRICAL CHARACTERISTICS (continued) ELECTRICAL CHARACTERISTICS (continued) (VCC = +2.7V to +28V, VRS+ = 0 to +28V, VSENSE = 0V, V RESET = 0V, RLOAD= 1M, TA = TMIN to TMAX, unless otherwise noted. Typical values are at TA = +25C.) (Note 1) PARAMETER SYMBOL Output High Leakage Current CONDITIONS MIN TYP MAX UNITS 1 A VCC = 28V, VPULL-UP = 5V (Note 10) RESET Input High Voltage VIH RESET Input Low Voltage VIL 2.0 V A Minimum RESET Pulse Width tRPW 1.5 s RESET Propagation Delay tRPD 3 s Note 7: Note 8: Note 9: Note 10: Note 11: -0.5 0.5 IIL, IIH Note 1: Note 2: Note 3: Note 4: Note 5: Note 6: VIL = 0, VIH = 5.5V, VCC = 28V V 0.8 Logic Input Current All devices are 100% production tested at TA = +25C. All temperature limits are guaranteed by design. Guaranteed by PSR test. Guaranteed by OUT Voltage Error test. Guaranteed by Gain Accuracy test. Output voltage is internally clamped not to exceed 12V. Total OUT Voltage Error and Full-Scale Accuracy are the sum of gain and offset voltage errors. Measured at IOUT = -500A (RLOAD = 4k for gain of +20V/V, RLOAD = 10k for gain of +50V/V, RLOAD = 20k for gain of +100V/V). +6.25mV = 1/16 of +100mV full-scale voltage. The device will not experience phase reversal when overdriven. All comparator tests are done with VRS+ = +12V. VPULL-UP is defined as an externally applied voltage through a resistor to pull up the comparator output. VOS is extrapolated from the gain accuracy test. Typical Operating Characteristics (VRS+ = +12V, VCC = +12V, R LOAD = 1M, V RESET = 0V, VSENSE = 100mV, VPULL-UP = +5V, RPULL-UP = 10k, TA = +25C, unless otherwise noted.) MAX4373 30 20 1.0 49 48 47 MAX4373 5 10 15 20 SUPPLY VOLTAGE (V) 4 AV = +20V/V -0.5 VSENSE = 100mV -2.0 44 0 25 30 AV = +50V/V 0 VSENSE = 5mV 0 AV = +100V/V -1.5 45 VSENSE = 5mV 0.5 -1.0 46 10 1.5 MAX4374/MAX4375 50 MAX4373 toc03 51 SUPPLY CURRENT (A) 50 2.0 OUTPUT ERROR (%) MAX4374/MAX4375 MAX4373 toc02 52 MAX4373 toc01 60 40 TOTAL OUTPUT ERROR vs. SUPPLY VOLTAGE SUPPLY CURRENT vs. COMMON-MODE VOLTAGE SUPPLY CURRENT vs. SUPPLY VOLTAGE SUPPLY CURRENT (A) MAX4373/MAX4374/MAX4375 Low-Cost, Micropower, High-Side Current-Sense Amplifier + Comparator + Reference ICs 0 5 10 15 20 25 COMMON-MODE VOLTAGE (V) 30 2 4 6 8 10 12 14 16 18 20 22 24 26 28 SUPPLY VOLTAGE (V) _______________________________________________________________________________________ Low-Cost, Micropower, High-Side Current-Sense Amplifier + Comparator + Reference ICs TOTAL OUTPUT ERROR vs. SUPPLY VOLTAGE TOTAL OUTPUT ERROR vs. SENSE VOLTAGE 1.0 OUTPUT ERROR (%) 2 1 AV = +20V/V -2 -3 AV = +20V/V -0.5 -1.0 AV = +50V/V -2.0 -1.5 -2.5 25 SUPPLY VOLTAGE (V) 50 75 100 125 150 10 AV = +100V/V AV = +50V/V 1.5 AV = +20V/V 125 150 AV = +50V/V 2 -2 AV = +20V/V 2 4 6 8 10 12 14 16 18 20 22 24 26 28 VSENSE (mV) COMMON-MODE VOLTAGE (V) SMALL-SIGNAL PULSE RESPONSE (AV = +20V/V) SMALL-SIGNAL PULSE RESPONSE (AV = +50V/V) MAX4373 toc11 INPUT 30mV 30mV 10mV 10mV 10mV 600mV 1.5V 3V 200mV OUTPUT INPUT SMALL-SIGNAL PULSE RESPONSE (AV = +100V/V) MAX4373 toc10 MAX4373 toc09 30mV 150 4 0 100 125 6 0 75 100 AV = +100V/V 8 0.5 50 75 MAX4373 toc08 MAX4373 toc07 12 2.0 20s/div 50 VSENSE (mV) OUTPUT ERROR (%) OUTPUT ERROR (%) 2.5 25 25 TOTAL OUTPUT ERROR vs. COMMON-MODE VOLTAGE VCC = +28V 0 0 VSENSE (mV) TOTAL OUTPUT ERROR vs. SENSE VOLTAGE 1.0 AV = +50V/V -2.0 0 3.0 AV = +20V/V 0 -0.5 -1.0 2 4 6 8 10 12 14 16 18 20 22 24 26 28 AV = +100V/V 0.5 -1.5 VSENSE = 6.25mV -5 1.0 INPUT -4 AV = +100V/V 500mV 20s/div OUTPUT 0 -1 1.5 0.5 0 MAX4373 toc06 VCC = +5.5V OUTPUT ERROR (%) AV = +50V/V OUTPUT OUTPUT ERROR (%) AV = +100V/V 2.0 MAX4373 toc05 4 3 1.5 MAX4373 toc04 5 TOTAL OUTPUT ERROR vs. SENSE VOLTAGE 1V 20s/div _______________________________________________________________________________________ 5 MAX4373/MAX4374/MAX4375 Typical Operating Characteristics (continued) (VRS+ = +12V, VCC = +12V, R LOAD = 1M, V RESET = 0V, VSENSE = 100mV, VPULL-UP = +5V, RPULL-UP = 10k, TA = +25C, unless otherwise noted.) Typical Operating Characteristics (continued) (VRS+ = +12V, VCC = +12V, R LOAD = 1M, V RESET = 0V, VSENSE = 100mV, VPULL-UP = +5V, RPULL-UP = 10k, TA = +25C, unless otherwise noted.) LARGE-SIGNAL PULSE RESPONSE (AV = +100V/V) LARGE-SIGNAL PULSE RESPONSE (AV = +50V/V) LARGE-SIGNAL PULSE RESPONSE (AV = +20V/V) 50mV 5mV 3V 7.5V 9.5V 2.5V 20s/div POWER-SUPPLY REJECTION vs. FREQUENCY COMMON-MODE REJECTION vs. FREQUENCY -20 -30 -30 -40 -40 PSR (dB) -50 -60 -70 -70 -80 -80 -90 -90 -100 -100 100 1k 10k 100k 10 100 1k 10k FREQUENCY (Hz) FREQUENCY (Hz) SMALL-SIGNAL GAIN vs. FREQUENCY LARGE-SIGNAL GAIN vs. FREQUENCY 5 MAX4373 toc17 4 3 2 3 2 AV = +20V/V AV = +50V/V 0 AV = +100V/V -3 -4 -4 -5 -5 1000k AV = +50V/V -1 -3 100k 100k 0 -2 FREQUENCY (Hz) AV = +20V/V 1 -2 10k VIN = 100mVP-P (20, 50) VIN = 50mVP-P (100) 4 GAIN (dB) GAIN (dB) MAX4373 toc16 -50 -60 MAX4373 toc18 CMR (dB) -10 -20 5 6 0 MAX4373 toc15 0 -10 1k 500mV 20s/div 20s/div -1 OUTPUT 50mV 1V 1 95mV INPUT INPUT 150mV OUTPUT INPUT 150mV 10 MAX4373 toc14 MAX4373 toc13 MAX4373 toc12 OUTPUT MAX4373/MAX4374/MAX4375 Low-Cost, Micropower, High-Side Current-Sense Amplifier + Comparator + Reference ICs AV = +100V/V 1k 10k FREQUENCY (Hz) _______________________________________________________________________________________ 100k Low-Cost, Micropower, High-Side Current-Sense Amplifier + Comparator + Reference ICs COMPARATOR POWER-UP DELAY POWER-UP DELAY MAX4373 toc20 MAX4373 toc19 VCC = VPULL-UP AV = +20V/V 5V 6V VCC VCC 0 0 5V 2V OUTPUT OUTPUT 0 0 10s/div 100s/div COMPARATOR TRIP POINT vs. SUPPLY VOLTAGE 598 597 MAX4373 toc22 599 TRIP POINT (mV) COMPARATOR PROPAGATION DELAY MAX4373 toc21 600 VOD = 5mV INPUT 125mV/div 596 595 594 593 OUTPUT 2.5V/div 592 591 590 0 5 10 15 20 25 30 2s/div SUPPLY VOLTAGE (V) COMPARATOR PROPAGATION DELAY vs. OVERDRIVE VOLTAGE VOD = 5mV 6 PROPAGATION DELAY (s) 3.4 3.2 3.0 2.8 2.6 2.4 MAX4373 toc26 3.6 PROGAGATION DELAY (s) 7 MAX4373 toc24 3.8 COMPARATOR PROPAGATION DELAY vs. TEMPERATURE 5 4 3 2 1 2.2 2 0 0 20 40 60 80 100 120 140 160 180 200 OVERDRIVE VOLTAGE (mV) -50 -30 -10 10 30 50 70 90 TEMPERATURE (C) _______________________________________________________________________________________ 7 MAX4373/MAX4374/MAX4375 Typical Operating Characteristics (continued) (VRS+ = +12V, VCC = +12V, R LOAD = 1M, V RESET = 0V, VSENSE = 100mV, VPULL-UP = +5V, RPULL-UP = 10k, TA = +25C, unless otherwise noted.) Typical Operating Characteristics (continued) (VRS+ = +12V, VCC = +12V, R LOAD = 1M, V RESET = 0V, VSENSE = 100mV, VPULL-UP = +5V, RPULL-UP = 10k, TA = +25C, unless otherwise noted.) COMPARATOR RESET VOLTAGE vs. SUPPLY VOLTAGE MAX4373 toc28 1.8 80 70 60 1.6 VOL (mV) RESET VOLTAGE (V) COMPARATOR VOL vs. ISINK 90 MAX4373 toc27 2.0 1.4 1.2 50 40 30 20 1.0 10 0.8 0 5 10 15 20 25 30 0 0.2 0.4 0.6 SUPPLY VOLTAGE (V) 0.8 1.0 1.2 1.4 1.6 ISINK (mA) TOTAL OUTPUT ERROR vs. TEMPERATURE SUPPLY CURRENT vs. TEMPERATURE MAX4373 toc31 250mV 5V OUTPUT 60 SUPPLY CURRENT (A) INPUT 1.0 MAX4373 toc32 70 750mV MAX4374 MAX4375 TOTAL OUTPUT ERROR (%) COMPARATOR AC RESPONSE 50 40 MAX4373 30 20 MAX4373 toc33 0 0.8 0.6 0.4 0.2 0 10 VSENSE = 5mV 0 0 10s/div -60 -40 -20 0 20 40 60 80 -60 100 -40 -20 GAIN ACCURACY vs. TEMPERATURE 20 COMPARATOR TRIP POINT vs. TEMPERATURE AV = +20V/V, +50V/V AV = +100V/V 0.4 0.2 MAX4373 toc35 0.8 605 604 COMPARATOR TRIP POINT (mV) MAX4373 toc34 1.0 0.6 0 603 602 601 600 599 598 597 596 0 595 -60 -40 -20 0 20 40 TEMPERATURE (C) 8 60 80 100 40 TEMPERATURE (C) TEMPERATURE (C) GAIN ACCURACY (%) MAX4373/MAX4374/MAX4375 Low-Cost, Micropower, High-Side Current-Sense Amplifier + Comparator + Reference ICs -60 -40 -20 0 20 40 60 TEMPERATURE (C) _______________________________________________________________________________________ 80 100 60 80 100 Low-Cost, Micropower, High-Side Current-Sense Amplifier + Comparator + Reference ICs PIN NAME FUNCTION MAX4373 MAX4374/MAX4375 MAX/SO MAX SO 1 1 1 VCC Supply Voltage Input 2 2 2 OUT Voltage Output. VOUT is proportional to VSENSE (VRS+ - VRS-). 3 3 4 CIN1 Comparator Input 1. Positive input of an internal comparator. The negative terminal is connected to a 0.6V internal reference. -- 4 5 CIN2 Comparator Input 2. Terminal of a second internal comparator. The positive terminal for the MAX4374 and the negative terminal for the MAX4375. The other terminal is connected to a 0.6V internal reference. 4 5 7 GND Ground 5 6 8 RESET Reset Input. Resets the output latch of the comparator at CIN1. 6 8 11 COUT1 Open-Drain Comparator Output. Latching output of the comparator controlled by CIN1. Connect RESET to GND to disable the latch. -- 7 10 COUT2 Open-Drain Comparator Output. Output of the second unlatched internal comparator. 7 9 13 RS- Load-Side Connection for the External Sense Resistor 8 10 14 RS+ Power Connection to the External Sense Resistor -- -- 3, 6, 9, 12 N.C. No Connection. Not internally connected. FUNCTION Detailed Description + VSENSE - VIN = 0 TO 28V RSENSE RS+ LOAD RS- VCC CURRENTSENSE AMPLIFIER VPULL-UP (UP TO 5V) R3 VPULL-UP (UP TO 5V) R6 COUT1 + - OUT R1 +(-) -(+) 0.6V BANDGAP REFERENCE MAX4374 (MAX4375) GND Figure 1. Functional Diagram Current-Sense Amplifier R2 RESET COUT2 R4 CIN1 The MAX4373 high-side current-sense supervisor features a high-side current-sense amplifier, bandgap reference, and comparator with latching output to monitor a supply for an overcurrent condition (Figure 1). The latching output allows the comparator to shut down a power supply without oscillations. The MAX4374/ MAX4375 offer an additional comparator to allow window detection of the current. CIN2 R5 The internal current-sense amplifier features a 0V to +28V input common-mode range that is independent of the supply voltage. With this feature, the device can monitor the output current of a battery in deep discharge and also high-side current-sensing voltages exceeding VCC. The current-sense amplifier is also suitable for low-side current sensing. However, the total output voltage error will increase when VRS+ falls below 2V, as shown in the Electrical Characteristics and Typical Operating Characteristics. _______________________________________________________________________________________ 9 MAX4373/MAX4374/MAX4375 Pin Description MAX4373/MAX4374/MAX4375 Low-Cost, Micropower, High-Side Current-Sense Amplifier + Comparator + Reference ICs Internal Comparator(s) The MAX4373/MAX4374/MAX4375 contain an opendrain output comparator for current limiting. The comparator's negative terminal is connected to the internal 600mV reference. The positive terminal is accessible at CIN1. When RESET is high, the internal latch is active, and once CIN1 rises above 600mV, the output latches into the open state. Pulsing RESET low for 1.5s resets the latch, and holding RESET low makes the latch transparent. See RESET at Power-Up section The MAX4374/MAX4375 contain an additional opendrain comparator. The negative terminal of the MAX4374's additional comparator and the positive terminal of the MAX4375's additional comparator are connected to the internal 600mV reference as shown in Figure 1. The positive terminal of the MAX4374's additional comparator and the negative terminal of the MAX4375's additional comparator are accessible at CIN2. LOAD RS+ RS- 2.7V TO 5.5V OUT COUT1 VCC MAX4373 R CIN1 RESET PUSHBUTTON C GND ___________Applications Information Recommended Component Values Ideally, the maximum load current will develop the fullscale sense voltage across the current-sense resistor. Choose the gain version needed to yield the maximum output voltage required for the application: VOUT = VSENSE x AV where VSENSE is the full-scale sense voltage, 150mV for gains of +20V/V and +50V/V or 100mV for a gain of +100V/V. AV is the gain of the device. The minimum supply voltage is VOUT + 0.25V. Note that the output for the gain of +100V/V is internally clamped at 12V. Calculate the maximum value for RSENSE so that the differential voltage across RS+ and RS- does not exceed the full-scale sense voltage: RSENSE(MAX) = VSENSE(MAX) ILOAD Choose the highest value resistance possible to maximize VSENSE and thus minimize total output error. In applications monitoring high current, ensure that RSENSE is able to dissipate its own I2R loss. If the resistor's power dissipation is exceeded, its value may drift or it may fail altogether, causing a differential voltage across the terminals in excess of the absolute maximum ratings. Use resistors specified for current-sensing applications. 10 Figure 2. MAX4373 Overcurrent Protection Circuit Overcurrent Protection Circuit The overcurrent protection circuit, shown in Figure 2, uses the MAX4373 to control an external P-channel MOSFET. The MOSFET controlled by the MAX4373 opens the current path under overload conditions. The latched output of the MAX4373's comparator prevents the circuit from oscillating, and the pushbutton resets the current path after an overcurrent condition. Window Detection Circuit Figure 3 shows a simple circuit suitable for window detection. Let I OVER be the minimum load current IUNDER = R4 + R5 VREF RSENSE x AV R5 and IOVER = R1 + R2 VREF RSENSE x AV R2 (ILOAD) required to cause a low state at COUT2, and let IUNDER be the maximum load current required to cause a high state at COUT1: where AV is the gain of the device and VREF is the internal reference voltage (0.6V typ). Connect COUT1 and COUT2; the resulting comparator output will be high when the current is inside the current window and low when the current is outside the window. The window is defined as load currents less than IOVER and greater than IUNDER. ______________________________________________________________________________________ Low-Cost, Micropower, High-Side Current-Sense Amplifier + Comparator + Reference ICs VIN = 0 TO 28V RSENSE LOAD RS+ VCC = 2.7V TO 28V RS- VCC OUT VPULL-UP (UP TO 5V) R1 MAX4375 R3 CIN2 COUT1 R4 R2 CIN1 COUT2 GND RESET R5 GND The RESET pin is used to control the latch function of comparator 1. Holding RESET low (<0.8V) makes the latch transparent and COUT1 will respond to changes at CIN1, above and below the internal 600mV reference threshold voltage. When RESET is high (>2.0V), once CIN1 rises above 600mV, COUT1 latches into the open-drain OFF state and remains in this state even if CIN1 drops below 600mV. Pulsing RESET low for at least 1.5s resets the latch. There is no internal circuitry to control the reset function during power-up. To prevent false latching, RESET must be held low until the VCC power has risen above the 2.7V minimum operating supply voltage. This is easily accomplished when RESET is driven under C or logic gate control. However, if RESET is to be always connected high, add an RC between VCC, RESET and GND (see Figure 2). Note that RESET cannot exceed VCC + 0.3V or +12V, whichever is less. The following formula can be used to determine the appropriate RC value. Figure 3. MAX4375 Window Detector RC = Power-Supply Bypassing It is recommended that VCC be bypassed to GND with at least a 0.1F ceramic capacitor to isolate the IC from supply voltage transients. It is possible that plugging in/out a battery or AC adapter/charger could cause large, fast line transients (>5V/s) at VCC. The simplest solution is to run VCC from a better regulated supply (+5V for example), since VCC and RS+ (or RS-) do not have to be connected together. For high-speed VCC transients, another solution is to add a resistor in series with the VCC pin and a 0.1F capacitor to create an RC time constant to slow the rise time of the transient. Since these current-sense amplifiers consume less than 100A, even a 2.5k resistor only drops an extra 250mV at VCC. For most applications with fast transients, 1k in conjunction with a 0.1F bypass capacitor works well. T T = ln(2.7V /(2.7V - 0.8V)) 0.3514 where T is the maximum time for VCC to reach 2.7V and 0.8V is the maximum RESET logic low voltage. For example, a 470k resistor and 0.22F capacitor will keep RESET low during a power-up time of up to 36ms. A faster power-up time is also safe with the calculated R and C since the capacitor will have even less time to charge. ______________________________________________________________________________________ 11 MAX4373/MAX4374/MAX4375 RESET at Power-Up ILOAD + VSENSE - MAX4373/MAX4374/MAX4375 Low-Cost, Micropower, High-Side Current-Sense Amplifier + Comparator + Reference ICs Pin Configurations TOP VIEW + + CIN1 14 RS+ OUT 2 13 RS- 10 RS+ N.C. 3 12 N.C. 9 RS- CIN1 4 8 COUT1 CIN2 5 7 COUT2 N.C. 6 9 N.C. RESET GND 7 8 RESET + VCC 1 OUT 2 VCC 1 8 MAX4373 7 RS+ RS- 3 6 COUT1 GND 4 5 RESET VCC 1 OUT 2 CIN1 3 MAX4374 MAX4375 CIN2 4 GND 5 6 Ordering Information (continued) PART TEMP RANGE PINPACKAGE GAIN (V/V) MAX4374TEUB+ -40C to +85C 10 MAX +20 MAX4374TESD+ -40C to +85C 14 SO +20 MAX4374FEUB+ -40C to +85C 10 MAX +50 MAX4374FESD+ -40C to +85C 14 SO +50 MAX4374HEUB+ -40C to +85C 10 MAX +100 MAX4374HESD+ -40C to +85C 14 SO +100 MAX4375TEUB+ -40C to +85C 10 MAX +20 MAX4375TESD+ -40C to +85C 14 SO +20 MAX4375FEUB+ -40C to +85C 10 MAX +50 MAX4375FESD+ -40C to +85C 14 SO +50 10 COUT2 ___________________Chip Information SUBSTRATE CONNECTED TO GND Package Information (For the latest package outline information and land patterns, go to www.maxim-ic.com/packages. Note that a "+", "#", or "-" in the package code indicates RoHS status only. Package drawings may show a different suffix character, but the drawing pertains to the package regardless of RoHS status. DOCUMENT LAND NO. PATTERN NO. PACKAGE TYPE PACKAGE CODE 8 SOIC S8+2 21-0041 90-0096 8 MAX U8+1 21-0036 90-0092 U10+2 21-0061 90-0330 S14+1 21-0041 90-0096 MAX4375HEUB+ -40C to +85C 10 MAX +100 10 MAX MAX4375HESD+ -40C to +85C 14 SO +100 14 SOIC +Denotes a lead(Pb)-free/RoHS-compliant package. 12 11 COUT1 SO MAX MAX/SO MAX4374 MAX4375 ______________________________________________________________________________________ Low-Cost, Micropower, High-Side Current-Sense Amplifier + Comparator + Reference ICs REVISION NUMBER REVISION DATE 3 6/10 Clarified 0V to 2V is not a high-accuracy range for the device, added lead-free options and soldering temperature 4 1/11 Clarified VRS+ conditions in Electrical Characteristics table DESCRIPTION PAGES CHANGED 1, 2, 12 2 Maxim cannot assume responsibility for use of any circuitry other than circuitry entirely embodied in a Maxim product. No circuit patent licenses are implied. Maxim reserves the right to change the circuitry and specifications without notice at any time. Maxim Integrated Products, 120 San Gabriel Drive, Sunnyvale, CA 94086 408-737-7600 ____________________ 13 (c) 2011 Maxim Integrated Products Maxim is a registered trademark of Maxim Integrated Products, Inc. MAX4373/MAX4374/MAX4375 Revision History