RT7264A

RT7264A RICHTEK | Alldatasheet

Document overview

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Technical content

Features

zzzzz Wide Input Range : 4.5V to 21V zzzzz Adjustable Output from 0.808V to 15V zzzzz 4A Output Current zzzzz 120mΩΩΩΩΩ/40mΩΩΩΩΩ Internal Power MOSFET Switch zzzzz Internal Compensation Minimizes External Parts zzzzz 500kHz Fixed Switching Frequency zzzzz Synchronized External Clock from 300kHz to 2MHz zzzzz Adjustable Soft-Start zzzzz Cycle-by-Cycle Over Current Limit zzzzz Thermal Shutdown Protection zzzzz Available in SOP-8 (Exposed Pad) and WDFN-14L 4x3 Packages zzzzz RoHS Compliant and Halogen Free

Ordering Information

Note : Richtek products are : \ RoHS compliant and compatible with the current require- ments of IPC/JEDEC J-STD-020. \ Suitable for use in SnPb or Pb-free soldering processes.

Applications

z Distributive Power Systems z Battery Charger z DSL Modems z Pre-Regulator for Linear Regulators Package Type QW : WDFN-14L 4x3 (W-Type) SP : SOP-8 (Exposed Pad-Option 2) RT7264A Lead Plating System Z : ECO (Ecological Element with Halogen Free and Pb free) Simplified Application Circuit VIN EN/SYNC GND BOOT FB SW L RT7264A CBOOT RT CIN COUT VCC CC VIN VOUTChip Enable

DS7264A-01 September 2012www.richtek.com ©Copyright 2012 Richtek Technology Corporation. All rights reserved. is a registered trademark of Ric htek Technology Corporation. Functional Pin Description Pin No. WDFN-14L 4x3 SOP-8 (Exposed Pad) Pin Name Pin Function 1 1 VIN Power Input. VIN supplies the power to the IC, as well as the step-down converter switches. Drive VIN with a 4.5V to 21V power source. Bypass VIN to GND with a suitably large capacitor to eliminate noise on the input to the IC. 2, 3, 4, 5 2, 3 SW Switch Node. SW is the switching node that supplies power to the output. Connect the output LC filter from SW to the output load. Note that a capacitor is required from SW to BOOT to power the high side switch. 6 4 BOOT Bootstrap for High Side Gate Driver. Connect a 100nF or greater capacitor from SW to BOOT to power the high side switch driver. 7 5 EN/SYNC Enable or External Frequency Synchronization Input. For automatic start-up, connect the EN/SYNC pin to VIN with a 100kΩ resistor. The switching frequency can be changed by an external clock applying to the SYNC pin. 8 6 FB Feedback Input. FB senses the output voltage via an external resistive voltage divider. The feedback reference voltage is 0.808V typically. 9 -- PGOOD Power Good Indicator is an Open Drain Output. The power good rising/falling threshold is 90%/70% of regulation output voltage. 10 -- SS Soft-Start Control Input. Connect a capacitor from SS to GND to set the soft-start period. 11 7 V CC Bias Supply. Decouple with 0.1 μF to 0.22 μF capacitor between this pin and GND. 12, 13, 15 (Exposed Pad) 9 (Exposed Pad) GND Ground. The exposed pad must be soldered to a large PCB and connected to GND for maximum power dissipation. 14 -- AGND Analog Ground. Connect this pin to the system ground in PCB layout. Pin ConfigurationsMarking Information SOP-8 (Exposed Pad) (TOP VIEW) WDFN-14L 4x3 VIN SW SW SW AGND GND GND SS VCC SW BOOT PGOOD EN/SYNC FB GND 1578 VIN SW SW BOOT GND VCC EN/SYNC FB GND 4 5 11 : Product Code YMDNN : Date Code RT7264AZQW RT7264AZSP : Product Number YMDNN : Date Code RT7264AZSP 11 YM DNN RT7264A ZSPYMDNN

DS7264A-01 September 2012 www.richtek.com ©Copyright 2012 Richtek Technology Corporation. All rights reserved. is a registered trademark of Ric htek Technology Corporation. Function Block Diagram For WDFN-14L 4x3 Package For SOP-8 (Exposed Pad) Package Regulator VIN VA VC 1.2V Shutdown Comparator FB SS PGOOD EN/SYNC VCC 1.7V 1µA Lockout Comparator Reference VC Error Amplifier 10µA 400k30pF 1pF S Q R Driver Current Sense Amplifier PWM Comparator Oscillator Ramp Generator SW BOOT GND VA S Q R Driver Current Sense Amplifier PWM Comparator Oscillator Ramp Generator Regulator Reference + Error Amplifier SW BOOT FB EN/SYNC VIN GND VCC 1.2V 1.7V 1µA Lockout Comparator Shutdown Comparator 400k30pF 1pF

DS7264A-01 September 2012www.richtek.com ©Copyright 2012 Richtek Technology Corporation. All rights reserved. is a registered trademark of Ric htek Technology Corporation. Operation The RT7264A is a constant frequency, current mode synchronous step-down converter. In normal operation, the high side N-MOSFET is turned on when the S-R latch is set by the oscillator and is turned off when the current comparator resets the S-R latch. While the high side N-MOSFET is turned off, the low side N-MOSFET is turned on to conduct the inductor current until next cycle begins. Error Amplifier The error amplifier adjusts its output voltage by comparing the feedback signal (V FB) with the internal reference. When the load current increases, it causes a drop in the feedback voltage relative to the reference, the error amplifier's output voltage then rises to allow higher inductor current to match the load current. Oscillator The internal oscillator runs at fixed frequency 500kHz. In short circuit condition, the frequency is reduced to 150kHz for low power consumption. Internal Regulator The regulator provides low voltage power to supply the internal control circuits and the bootstrap power for high side gate driver. Enable The converter is turned on when the EN pin is higher than 2V. When the EN pin is lower than 0.4V, the converter will enter shutdown mode and reduce the supply current to be less than 1μA. Soft-Start (SS) An internal current source charges an internal capacitor to build a soft-start ramp voltage. The FB voltage will track the internal ramp voltage during soft-start interval. The typical soft-start time is 4ms. UV Comparator If the feedback voltage (V FB) is lower than 0.4V, the UV Comparator will go high to turn off the high side MOSFET. The output under voltage protection is designed to operate in Hiccup mode. When the UV condition is removed, the converter will resume switching. Thermal Shutdown The over temperature protection function will shut down the switching operation when the junction temperature exceeds 150 °C. Once the junction temperature cools down by approximately 30 °C, the converter will automatically resume switching.

DS7264A-01 September 2012 www.richtek.com ©Copyright 2012 Richtek Technology Corporation. All rights reserved. is a registered trademark of Ric htek Technology Corporation. Absolute Maximum Ratings (Note 1) z Power Dissipation, PD @ TA = 25°C z Package Thermal Resistance (Note 2) z ESD Susceptibility (Note 3) Recommended Operating Conditions (Note 4)

Electrical Characteristics

Parameter Symbol Test Conditions Min Typ Max Unit Shutdown Current I SHDN V EN = 0 -- 0 1 μA Quiescent Current I Q V EN = 2V, VFB = 1V -- 0.7 -- mA Upper Switch On Resistance R DS(ON)1 -- 120 -- m Ω Lower Switch On Resistance R DS(ON)2 -- 40 -- m Ω Switch Leakage I LEAK V EN = 0V, VSW = 0V or 12V -- 0 10 μA Current Limit I LIM V BOOT − VSW = 4.8V 5.9 7.5 -- A Oscillator Frequency f SW V FB = 0.75V 425 500 575 kHz Short Circuit Frequency V FB = 0V -- 150 -- kHz Maximum Duty Cycle D MAX V FB = 0.8V -- 90 -- % Minimum On Time t ON -- 100 -- ns Feedback Voltage V FB 4.5V ≤ VIN ≤ 21V 0.796 0.808 0.82 V Feedback Current I FB -- 10 50 nA Logic-High V IH 2 -- 5.5 EN Voltage Logic-Low V IL -- -- 0.4 V (VIN = 12V, TA = 25°C unless otherwise specified)

DS7264A-01 September 2012www.richtek.com ©Copyright 2012 Richtek Technology Corporation. All rights reserved. is a registered trademark of Ric htek Technology Corporation. Parameter Symbol Test Conditions Min Typ Max Unit VEN = 2V -- 1 -- EN Current I EN VEN = 0V -- 0 -- μA Logic-High V SYNCH 1.8 -- -- SYNC Threshold Voltage Logic-Low VSYNCL -- -- 0.4 V SYNC Frequency Range f SYNC 0.3 -- 2 MHz SYNC Input Current I SYNC V SYNC = 6V -- 1.5 2.5 μA Power Good Rising Threshold -- 90 -- % Power Good Falling Threshold -- 70 -- % Power Good Sink Current Capability Sink 4mA -- -- 0.4 V Power Good Leakage Current -- 10 -- nA Under Voltage Lockout Threshold VUVLO V IN Rising 3.8 4 4.2 V Under Voltage Lockout Threshold Hysteresis ΔVUVLO -- 400 -- mV VCC Regulator -- 5 -- V VCC Load Regulation I CC = 5mA -- 5 -- % Soft-Start Period t SS C SS = 47nF -- 4.7 -- ms Thermal Shutdown Threshold T SD -- 150 -- Thermal Shutdown Hysteresis ΔTSD -- 30 -- Note 1. Stresses beyond those listed “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 may affect device reliability. Note 2. θ JA is measured at T A = 25 °C on a high effective thermal conductivity four-layer test board per JEDEC 51-7. θJC is measured at the exposed pad of the package. Note 3. Devices are ESD sensitive. Handling precaution is recommended. Note 4. The device is not guaranteed to function outside its operating conditions.

©Copyright 2012 Richtek Technology Corporation. All rights reserved. is a registered trademark of Ric htek Technology Corporation. Table 1. Recommended Components Selection

DS7264A-01 September 2012www.richtek.com ©Copyright 2012 Richtek Technology Corporation. All rights reserved. is a registered trademark of Ric htek Technology Corporation. Switching Frequency vs. Temperature 300 350 400 450 500 550 600 650 -50 -25 0 25 50 75 100 125 Temperature (°C) Switching Frequency (kHz) 1 VIN = 12V, VOUT = 1.22V Reference Voltage vs. Temperature 0.76 0.77 0.78 0.79 0.80 0.81 0.82 0.83 0.84 -50 -25 0 25 50 75 100 125 Temperature (°C) Reference Voltage (V) Reference Voltage vs. Input Voltage 0.785 0.790 0.795 0.800 0.805 0.810 0.815 0.820 0.825 4 6 8 10 12 14 16 18 20 22 Input Voltage (V) Reference Voltage (V) Typical Operating Characteristics Efficiency vs. Output Current 100 00 . 511 . 522 . 533 . 54 Output Current (A) Efficiency (%) VOUT = 1.22V, IOUT = 0A to 4A VIN = 12V VIN = 21V Output Voltage vs. Output Current 1.18 1.19 1.20 1.21 1.22 1.23 1.24 1.25 1.26 00 . 511 . 522 . 533 . 54 Output Current (A) Output Voltage (V) VOUT = 1.22V, IOUT = 0A to 4A VIN = 21V VIN = 12V Switching Frequency vs. Input Voltage 400 425 450 475 500 525 550 4 6 8 10 12 14 16 18 20 22 Input Voltage (V) Switching Frequency (kHz) 1 VOUT = 1.22V

DS7264A-01 September 2012 www.richtek.com ©Copyright 2012 Richtek Technology Corporation. All rights reserved. is a registered trademark of Ric htek Technology Corporation. Current Limit vs. Input Voltage 4 6 8 10 12 14 16 18 20 22 Input Voltage (V) Current Limit (A) Current Limit vs. Temperature - 5 0- 2 5 0 2 5 5 0 7 51 0 0 1 2 5 Temperature (°C) Current Limit (A) VIN = 12V, VOUT = 1.22V Time (100 μs/Div) Load Transient Response VOUT (500mV/Div) IOUT (2A/Div) VIN = 12V, VOUT = 1.22V, IOUT = 1A to 4A Time (100 μs/Div) Load Transient Response VOUT (500mV/Div) IOUT (2A/Div) VIN = 12V, VOUT = 1.22V, IOUT = 0A to 4A Time (1 μs/Div) Output Ripple Voltage VOUT (50mV/Div) VSW (10V/Div) IL (2A/Div) VIN = 12V, IOUT = 4A Time (1 μs/Div) Output Ripple Voltage VOUT (50mV/Div) VSW (10V/Div) IL (1A/Div) VIN = 12V, IOUT = 1A

DS7264A-01 September 2012www.richtek.com ©Copyright 2012 Richtek Technology Corporation. All rights reserved. is a registered trademark of Ric htek Technology Corporation. Time (25ms/Div) Power Off from VIN VIN = 12V, VOUT = 1.22V, IOUT = 4A VOUT (1V/Div) VIN (10V/Div) IL (5A/Div) VPGOOD (5V/Div) Time (5ms/Div) Power On from VIN VIN = 12V, VOUT = 1.22V, IOUT = 4A VOUT (1V/Div) VIN (10V/Div) IL (5A/Div) VPGOOD (5V/Div) Time (2.5ms/Div) Power On from EN VIN = 12V, VOUT = 1.22V, IOUT = 4A VOUT (1V/Div) VEN (5V/Div) IL (5A/Div) VPGOOD (5V/Div) Time (50 μs/Div) Power Off from EN VIN = 12V, VOUT = 1.22V, IOUT = 4A VOUT (1V/Div) VEN (5V/Div) IL (5A/Div) VPGOOD (5V/Div)

©Copyright 2012 Richtek Technology Corporation. All rights reserved. is a registered trademark of Ric htek Technology Corporation. Table 2. Suggested Inductors for Typical trapezoidal current at the source of the high side MOSFET. meet size or height requirements in the design. capacitor, please refer to Table 3 for more detail. Table 3. Suggested Capacitors for CIN and COUT for COUT selection to ensure that the control loop is stable. inductor to attain this goal.

©Copyright 2012 Richtek Technology Corporation. All rights reserved. is a registered trademark of Ric htek Technology Corporation. cools down by approximately 30°C. Figure 7. Derating Curve of Maximum Power Dissipation \` Connect feedback network behind the output capacitors. on the maximum power dissipation.

DS7264A-01 September 2012www.richtek.com ©Copyright 2012 Richtek Technology Corporation. All rights reserved. is a registered trademark of Ric htek Technology Corporation. Outline Dimension W-Type 14L DFN 4x3 Package 1 122 Note : The configuration of the Pin #1 identifier is optional, but must be located within the zone indicated. DETAIL A Pin #1 ID and Tie Bar Mark Options Dimensions In Millimeters Dimensions In Inches Symbol Min Max Min Max A 0.700 0.800 0.028 0.031 A1 0.000 0.050 0.000 0.002 A3 0.175 0.250 0.007 0.010 b 0.180 0.300 0.007 0.012 D 3.900 4.100 0.154 0.161 D2 3.250 3.350 0.128 0.132 E 2.900 3.100 0.114 0.122 E2 1.650 1.750 0.065 0.069 e 0.500 0.020 L 0.350 0.450 0.014 0.018

DS7264A-01 September 2012 www.richtek.com Richtek Technology Corporation 5F, No. 20, Taiyuen Street, Chupei City Hsinchu, Taiwan, R.O.C. Tel: (8863)5526789 Richtek products are sold by description only. Richtek reserves the right to change the circuitry and/or specifications without notice at any time. Customers should obtain the latest relevant information and data sheets before placing orders and should verify that such information is current and complete. Richtek cannot assume responsibility for use of any circuitry other than circuitry entirely embodied in a Richtek product. Information furnish ed by Richtek is believed to be accurate and reliable. However, no responsibility is assumed by Richtek or its subsidiaries for its use; nor for any infringeme nts of patents or other rights of third parties which may result from its use. No license is granted by implication or otherwise under any patent or patent rights of R ichtek or its subsidiaries. A BJ F H M C D I Y X EXPOSED THERMAL PAD (Bottom of Package) 8-Lead SOP (Exposed Pad) Plastic Package Dimensions In Millimeters Dimensions In Inches Symbol 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 Option 1 Y 2.000 2.300 0.079 0.091 X 2.100 2.500 0.083 0.098 Option 2 Y 3.000 3.500 0.118 0.138