RT9173D Cost-Effective, Peak 3A Sink/Source Bus Termination Regulator General Description Features The RT9173D is a simple, cost-effective and high-speed linear regulator designed to generate termination voltage in double data rate (DDR) memory system to comply with the JEDEC SSTL_2 and SSTL_18 or other specific interfaces such as HSTL, SCSI-2 and SCSI-3 etc. devices requirements. The regulator is capable of actively sinking or sourcing continuous 2A or up to 3A transient peak current while regulating an output voltage to within 40mV. The output termination voltage cab be tightly regulated to track 1/2VDDQ by two external voltage divider resistors or the desired output voltage can be pro-grammed by externally forcing the REFEN pin voltage. z The RT9173D also incorporates a high-speed differential amplifier to provide ultra-fast response in line/load transient. Other features include extremely low initial offset voltage, excellent load regulation, current limiting in bi-directions and on-chip thermal shut-down protection. z z z z z z z z z z z z The RT9173D are available in the SOP-8 (Exposed Pad) surface mount packages. Ordering Information RT9173D Lead Plating System P : Pb Free G : Green (Halogen Free and Pb Free) Note : Sink and Source Current 2A Continuous Current Peak 3A for DDRI and DDRII Peak 2.5A for DDRIII Integrated Power MOSFETs Generates Termination Voltage for SSTL_2, SSTL _18, HSTL, SCSI-2 and SCSI-3 Interfaces High Accuracy Output Voltage at Full-Load Output Adjustment by Two External Resistors Low External Component Count Shutdown for Suspend to RAM (STR) Functionality with High-Impedance Output Current Limiting Protection On-Chip Thermal Protection Available in SOP-8 (Exposed Pad) Packages VIN and VCNTL No Power Sequence Issue RoHS Compliant and 100% Lead (Pb)-Free Applications z z z Package Type SP : SOP-8 (Exposed Pad-Option 1) Ideal for DDR-I, DDR-II and DDR-III VTT Applications z z z Desktop PCs, Notebooks, and Workstations Graphics Card Memory Termination Set Top Boxes, Digital TVs, Printers Embedded Systems Active Termination Buses DDR-I, DDR-II and DDR-III Memory Systems Pin Configurations Richtek products are : ments of IPC/JEDEC J-STD-020. (TOP VIEW) RoHS compliant and compatible with the current requireSuitable for use in SnPb or Pb-free soldering processes. 8 VIN GND 2 REFEN 3 VOUT 7 GND 6 9 4 5 NC NC VCNTL NC SOP-8 (Exposed Pad) DS9173D-07 April 2011 www.richtek.com 1 RT9173D Typical Application Circuit VCNTL = 3.3V VIN = 2.5V/1.8V/1.5V RTT R1 VIN 2N7002 EN VCNTL R2 CSS CCNTL CIN RT9173D REFEN VOUT GND COUT GND R1 = R2 = 100k, RTT = 50 / 33 / 25 COUT(MIN) = 10F (Ceramic) + 1000F under the worst case testing condition CSS = 1F, CIN = 470F (Low ESR), CCNTL = 47F Test Circuit 2.5V/1.8V/1.5V VIN 1.25V/0.9V/0.75V 3.3V VCNTL RT9173D REFEN VOUT VOUT GND Figure 1. Test Circuit for Typical Operating Characteristics Curves www.richtek.com 2 DS9173D-07 April 2011 RT9173D Functional Pin Description VIN (Pin 1) VOUT (Pin 4) Input voltage which supplies current to the output pin. Connect this pin to a well-decoupled supply voltage. To prevent the input rail from dropping during large load transient, a large, low ESR capacitor is recommended to use. The capacitor should be placed as close as possible to the VIN pin. Regulator output. VOUT is regulated to REFEN voltage that is used to terminate the bus resistors. It is capable of sinking and sourcing current while regulating the output rail. To maintain adequate large signal transient response, typical value of 1000F AL electrolytic capacitor with 10F ceramic capacitors are recommended to reduce the effects of current transients on VOUT. GND [Pin 2, Exposed pad (9)] VCNTL (Pin 6) Common Ground (Exposed pad is connected to GND). The GND pad area should be as large as possible and using many vias to conduct the heat into the buried GND plate of PCB layer. VCNTL supplies the internal control circuitry and provides the drive voltage. The driving capability of output current is proportioned to the VCNTL. Connect this pin to 3.3V bias supply to handle large output current with at least 10F capacitor from this pin to GND. REFEN (Pin 3) Reference voltage input and active low shutdown control pin. Two resistors dividing down the VIN voltage on the pin to create the regulated output voltage. Pulling the pin to ground turns off the device by an open-drain, such as 2N7002, signal N-MOSFET. NC (Pin 5, 7, 8) No Internal Connect. Function Block Diagram VCNTL VIN Current Limit Thermal Protection + REFEN VOUT EA GND DS9173D-07 April 2011 www.richtek.com 3 RT9173D Absolute Maximum Ratings z z z z z z z z (Note 1) Input Voltage, VIN ---------------------------------------------------------------------------------------------------Control Voltage, VCNTL ---------------------------------------------------------------------------------------------Power Dissipation, PD @ TA = 25C SOP-8 (Exposed Pad) ---------------------------------------------------------------------------------------------Package Thermal Resistance (Note 2) SOP-8 (Exposed Pad), JA ---------------------------------------------------------------------------------------SOP-8 (Exposed Pad), JC ---------------------------------------------------------------------------------------Junction Temperature ----------------------------------------------------------------------------------------------Lead Temperature (Soldering, 10 sec.) ------------------------------------------------------------------------Storage Temperature Range --------------------------------------------------------------------------------------ESD Susceptibility (Note 3) HBM (Human Body Mode) ----------------------------------------------------------------------------------------MM (Machine Mode) ------------------------------------------------------------------------------------------------ Recommended Operating Conditions z z z z 6V 6V 1.33W 75C/W 28C/W 125C 260C -65C to 150C 2kV 200V (Note 4) Input Voltage, VIN ---------------------------------------------------------------------------------------------------- 2.5V to 1.5V 5% Control Voltage, VCNTL ---------------------------------------------------------------------------------------------- 5V or 3.3V 5% Ambient Temperature Range -------------------------------------------------------------------------------------- -40C to 85C Junction Temperature Range -------------------------------------------------------------------------------------- -40C to 125C Electrical Characteristics (VIN = 2.5V/1.8V/1.5V, VCNTL = 3.3V, VREFEN = 1.25V/0.9V/0.75V, COUT = 10F (Ceramic), TA = 25 C, unless otherwise specified) Parameter Symbol Test Conditions Min Typ Max Unit Input VCNTL Operation Current ICNTL IOUT = 0A -- 1 2.5 mA Standby Current (Note 5) ISTBY V REFEN < 0.2V (Shutdown), RLOAD = 180 -- 50 90 A Output Offset Voltage (Note 6) VOS IOUT = 0A -20 -- +20 mV Load Regulation (Note 7) V LOAD -20 -- +20 mV -- 3.4 -- A Output (DDR / DDR II / DDR III) IOUT = +2A IOUT = -2A Protection Current limit ILIM V IN = 2.5V/1.8V/1.5V Thermal Shutdown Temperature TSD 3.3V VCNTL 5V 125 170 -- C Thermal Shutdown Hysteresis TSD 3.3V VCNTL 5V -- 35 -- C VIH Enable 0.6 -- -- VIL Shutdown -- -- 0.2 REFEN Shutdown Shutdown Threshold www.richtek.com 4 V DS9173D-07 April 2011 RT9173D Note 1. Stresses listed as the above "Absolute Maximum Ratings" may cause permanent damage to the device. These are for stress ratings. 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 remain possibility to affect device reliability. Note 2. JA is measured in the natural convection at TA = 25C on a high effective thermal conductivity test board (4 Layers, 2S2P) of JEDEC 51-7 thermal measurement standard. The case point of JC is on the expose pad for SOP-8 (Exposed Pad) package. Note 3. Devices are ESD sensitive. Handling precaution recommended. Note 4. The device is not guaranteed to function outside its operating conditions. Note 5. Standby current is the input current drawn by a regulator when the output voltage is disabled by a shutdown signal on REFEN pin (VIL < 0.2V). It is measured with VIN = VCNTL = 5V. Note 6. VOS offset is the voltage measurement defined as VOUT subtracted from VREFEN. Note 7. Regulation is measured at constant junction temperature by using a 5ms current pulse. Devices are tested for load regulation in the load range from 0A to 2A. DS9173D-07 April 2011 www.richtek.com 5 RT9173D Typical Operating Characteristics Output Voltage vs. Temperature Output Voltage vs. Temperature 0.77 0.92 VIN = 1.5V 0.915 Output Voltage (V) 0.765 Output Voltage (V) VIN = 1.8V 0.76 0.755 0.75 0.91 0.905 0.9 0.895 0.745 0.89 0.74 -50 -25 0 25 50 75 100 -50 125 -25 0 Temperature (C) 100 125 Shutdown Threshold vs. Temperature VIN = 2.5V VCNTL = 5V, Turn On 0.55 Shutdown Threshold (V) Output Voltage (V) 75 0.6 1.265 1.26 1.255 1.25 1.245 VCNTL = 5V, Turn Off 0.5 0.45 0.4 VCNTL = 3.3V, Turn On 0.35 VCNTL = 3.3V, Turn Off 0.3 0.25 1.24 -50 -25 0 25 50 75 100 -50 125 -25 0 Temperature (C) 4 VIN 75 100 125 Vcntl Current vs. Temperature VIN = 1.8V, VCNTL = 3.3V VIN = 1.8V, VCNTL = 5V = 2.5V, VCNTL = 3.3V 0.55 VIN = 2.5V, VCNTL = 5V 3.5 3 VIN = 1.5V, VCNTL = 5V 2.5 50 0.6 Vcntl Current (mA) 4.5 25 Temperature (C) VIN Current vs. Temperature 5 V IN Current (mA) 50 Temperature (C) Output Voltage vs. Temperature 1.27 25 0.5 VIN VIN = 1.8V, VCNTL = 3.3V VIN = 1.8V, VCNTL = 5V VIN = 2.5V, VCNTL = 3.3V = 2.5V, VCNTL = 5V 0.45 0.4 VIN = 1.5V, VCNTL = 5V VIN = 1.5V, VCNTL = 3.3V 0.35 VIN = 1.5V, VCNTL = 3.3V 2 0.3 -50 -25 0 25 50 Temperature (C) www.richtek.com 6 75 100 125 -50 -25 0 25 50 75 100 125 Temperature (C) DS9173D-07 April 2011 RT9173D Sink Current Limit vs. Temperature Source Current Limit vs. Temperature 4.5 VIN = 1.8V, VCNTL = 5V VIN = 1.8V, VCNTL = 3.3V VIN = 2.5V, VCNTL = 5V VIN = 2.5V, VCNTL = 3.3V 4 3.5 3 Sink Current Limit (A) Source Current Limit (A) 4.5 VIN = 1.5V, VCNTL = 5V VIN = 1.5V, VCNTL = 3.3V 2.5 -25 0 25 50 75 100 3.5 3 VIN = 1.5V, VCNTL = 5V VIN = 1.5V, VCNTL = 3.3V 2.5 0 25 50 75 100 Temperature (C) 0.9VTT @ 2A Transient Response 0.9VTT @ 2A Transient Response Sink Output Voltage Transient (mV) VIN = 1.8V, VCNTL = 3.3V, VOUT = 0.9V 20 0 Output Current (A) -20 2 1 Swing Frequency : 1kHz VIN = 1.8V, VCNTL = 3.3V, VOUT = 0.9V Source 20 0 -20 2 1 0 Swing Frequency : 1kHz Time (250s/Div) 0.75VTT @ 2A Transient Response 0.75VTT @ 2A Transient Response 20 0 -20 2 1 Swing Frequency : 1kHz Time (250s/Div) DS9173D-07 April 2011 Sink Output Voltage Transient (mV) VIN = 1.5V, VCNTL = 3.3V, VOUT = 0.75V 125 40 Time (250s/Div) 40 0 -25 Temperature (C) 40 0 -50 125 Output Current (A) Output Current (A) Output Voltage Transient (mV) -50 Output Voltage Transient (mV) VIN 2 2 Output Current (A) 4 VIN = 1.8V, VCNTL = 3.3V VIN = 2.5V, VCNTL = 3.3V VIN = 2.5V, VCNTL = 5V = 1.8V, VCNTL = 5V VIN = 1.5V, VCNTL = 3.3V, VOUT = 0.75V Source 40 20 0 -20 2 1 0 Swing Frequency : 1kHz Time (250s/Div) www.richtek.com 7 RT9173D 20 0 Output Current (A) -20 2 1 0 12 Output Short Circuit (A) Sink Output Voltage Transient (mV) VIN = 2.5V, VCNTL = 3.3V, VOUT = 1.25V 40 1.25VTT @ 2A Transient Response Swing Frequency : 1kHz 20 0 -20 2 1 0 Swing Frequency : 1kHz Output Short-Circuit Protection Output Short-Circuit Protection VIN = 1.5V, VCNTL = 3.3V Sink 12 8 6 4 2 0 VIN = 1.5V, VCNTL = 3.3V Source 10 8 6 4 2 0 Time (1ms/Div) Time (1ms/Div) Output Short-Circuit Protection Output Short-Circuit Protection VIN = 1.8V, VCNTL = 3.3V 10 8 6 4 2 12 VIN = 1.8V, VCNTL = 3.3V Source 10 8 6 4 2 0 0 Time (1ms/Div) www.richtek.com 8 Sink Output Short Circuit (A) Output Short Circuit (A) Source Time (250s/Div) 10 12 VIN = 2.5V, VCNTL = 3.3V, VOUT = 1.25V 40 Time (250s/Div) Output Short Circuit (A) Output Current (A) Output Voltage Transient (mV) 1.25VTT @ 2A Transient Response Time (1ms/Div) DS9173D-07 April 2011 RT9173D Output Short-Circuit Protection Output Short-Circuit Protection VIN = 2.5V, VCNTL = 3.3V 10 8 6 4 2 12 Source VIN = 2.5V, VCNTL = 3.3V 10 8 6 4 2 0 0 Time (1ms/Div) DS9173D-07 April 2011 Sink Output Short Circuit (A) Output Short Circuit (A) 12 Time (1ms/Div) www.richtek.com 9 RT9173D Application Information Consideration while designs the resistance of voltage divider Make sure the sinking current capability of pull-down NMOS if the lower resistance was chosen so that the voltage on VREFEN is below 0.2V. In addition, the capacitor and voltage divider form the lowpass filter. There are two reasons doing this design; one is for output voltage soft-start while another is for noise immunity. How to reduce power dissipation on Notebook PC or the dual channel DDR SDRAM application? In notebook application, using RichTek's Patent " Distributed Bus Terminator Topology" with choosing RichTek's product is encouraged. General Regulator The RT9173D could also serves as a general linear regulator. The RT9173D accepts an external reference voltage at REFEN pin and provides output voltage regulated to this reference voltage as shown in Figure 3, where VOUT = VEXT x R2/(R1+R2) As other linear regulator, dropout voltage and thermal issue should be specially considered. Figure 4 and 5 show the RDS(ON) over temperature of RT9173D in PSOP-8 (Exposed Pad) package. The minimum dropout voltage could be obtained by the product of RDS(ON) and output current. For thermal consideration, please refer to the relative sections. RDS(ON) vs. Temperature 0.40 0.35 R0 BUS(0) R1 BUS(1) RT9173D R2 VOUT BUS(2) R3 R DS(ON) () Distributed Bus Terminating Topology Terminator Resistor 0.30 0.25 0.20 BUS(3) R4 0.15 BUS(4) REFEN R5 BUS(5) 0.10 R6 -50 BUS(6) RT9173D R7 VOUT VCNTL = 3.3V -25 0 BUS(7) R8 50 75 100 125 100 125 Figure 4 BUS(8) R9 25 Temperature (C) BUS(9) RDS(ON) vs. Temperature 0.40 R(2N) BUS(2N) 0.35 R(2N+1) BUS(2N+1) R DS(ON) () Figure 2 VEXT R1 R2 VCNTL VIN RT9173D REFEN VOUT GND VCNTL = 5V VOUT 0.30 0.25 0.20 0.15 0.10 -50 -25 0 25 50 75 Temperature (C) Figure 3 www.richtek.com 10 Figure 5 DS9173D-07 April 2011 RT9173D Input Capacitor and Layout Consideration Place the input bypass capacitor as close as possible to the RT9173D. A low ESR capacitor larger than 470uF is recommended for the input capacitor. Use short and wide traces to minimize parasitic resistance and inductance. Inappropriate layout may result in large parasitic inductance and cause undesired oscillation between RT9173D and the preceding power converter. Thermal Consideration Ambient Molding Compound Gold Line Die Pad Case (Exposed Pad) Figure 6. SOP-8 (Exposed Pad) Package Sectional Drawing RT9173D regulators have internal thermal limiting circuitry designed to protect the device during overload conditions. For continued operation, do not exceed maximum operation junction temperature 125C. The power dissipation definition in device is: PD = (VIN - VOUT) x IOUT + VIN x IQ The maximum power dissipation depends on the thermal resistance of IC package, PCB layout, the rate of surroundings airflow and temperature difference between junction to ambient. The maximum power dissipation can be calculated by following formula: Lead Frame RGOLD-LINE RLEAD FRAME RPCB path 1 Junction RDIE RDIE-ATTACH RDIE-PAD path 2 RPCB Case (Exposed Pad) Ambient RMOLDING-COMPOUND path 3 Figure 7. Thermal Resistance Equivalent Circuit PD(MAX) = ( TJ(MAX) -TA ) /JA Where T J(MAX) is the maximum operation junction temperature 125C, TA is the ambient temperature and the JA is the junction to ambient thermal resistance. The junction to ambient thermal resistance (JA is layout dependent) for SOP-8 package (Exposed Pad) is 75C/W on standard JEDEC 51-7 (4 layers, 2S2P) thermal test board. The maximum power dissipation at TA = 25C can be calculated by following formula: PD(MAX) = (125C - 25C) / 75C/W = 1.33W Figure 6 show the package sectional drawing of SOP-8 (Exposed Pad). Every package has several thermal dissipation paths. As show in Figure 7, the thermal resistance equivalent circuit of SOP-8 (Exposed Pad). The path 2 is the main path due to these materials thermal conductivity. We define the exposed pad is the case point of the path 2. The thermal resistance JA of SOP-8 (Exposed Pad) is determined by the package design and the PCB design. However, the package design has been decided. If possible, it's useful to increase thermal performance by the PCB design. The thermal resistance can be decreased by adding copper under the expose pad of SOP-8 package. About PCB layout, the Figure 8 show the relation between thermal resistance JA and copper area on a standard JEDEC 51-7 (4 layers, 2S2P) thermal test board at TA = 25C.We have to consider the copper couldn't stretch infinitely and avoid the tin overflow. We use the "dog-bone" copper patterns on the top layer as Figure 9. As shown in Figure 10, the amount of copper area to which the SOP-8 (Exposed Pad) is mounted affects thermal performance. When mounted to the standard SOP-8 (Exposed Pad) pad of 2 oz. copper (Figure 10.a), JA is 75C/W. Adding copper area of pad under the SOP-8 (Exposed Pad) (Figure 10.b) reduces the JA to 64C/W. Even further, increasing the copper area of pad to 70mm2 (Figure 10.e) reduces the JA to 49C/W. DS9173D-07 April 2011 www.richtek.com 11 RT9173D JA vs. Copper Area 100 90 JA (C/W) 80 70 60 50 Figure 10 (b). Copper Area = 10mm2, JA = 64C/W 40 30 0 10 20 30 40 50 60 70 2 Copper Area (mm ) Figure 8 Exposed Pad Figure 10 (c). Copper Area = 30mm2, JA = 54C/W Figure 9.Dog-Bone layout Figure 10 (d). Copper Area = 50mm2, JA = 51C/W Figure 10 (a). Minimum Footprint, JA = 75C/W Figure 10 (e). Copper Area = 70mm2, JA = 49C/W W2.28mm Figure 10. Thermal Resistance vs. Different Cooper Area Layout Design www.richtek.com 12 DS9173D-07 April 2011 RT9173D Outline Information H A M EXPOSED THERMAL PAD (Bottom of Package) Y J X B F C I D Dimensions In Millimeters Symbol Dimensions In Inches Min Max Min Max A 4.801 5.004 0.189 0.197 B 3.810 4.000 0.150 0.157 C 1.346 1.753 0.053 0.069 D 0.330 0.510 0.013 0.020 F 1.194 1.346 0.047 0.053 H 0.170 0.254 0.007 0.010 I 0.000 0.152 0.000 0.006 J 5.791 6.200 0.228 0.244 M 0.406 1.270 0.016 0.050 X 2.000 2.300 0.079 0.091 Y 2.000 2.300 0.079 0.091 X 2.100 2.500 0.083 0.098 Y 3.000 3.500 0.118 0.138 Option 1 Option 2 8-Lead SOP (Exposed Pad) Plastic Package Richtek Technology Corporation Richtek Technology Corporation Headquarter Taipei Office (Marketing) 5F, No. 20, Taiyuen Street, Chupei City 5F, No. 95, Minchiuan Road, Hsintien City Hsinchu, Taiwan, R.O.C. Taipei County, Taiwan, R.O.C. Tel: (8863)5526789 Fax: (8863)5526611 Tel: (8862)86672399 Fax: (8862)86672377 Email: marketing@richtek.com Information that is provided by Richtek Technology Corporation is believed to be accurate and reliable. Richtek reserves the right to make any change in circuit design, specification or other related things if necessary without notice at any time. No third party intellectual property infringement of the applications should be guaranteed by users when integrating Richtek products into any application. No legal responsibility for any said applications is assumed by Richtek. DS9173D-07 April 2011 www.richtek.com 13