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RT7263B Dataheets PDF



Part Number RT7263B
Manufacturers Richtek
Logo Richtek
Description Synchronous Step-Down Converter
Datasheet RT7263B DatasheetRT7263B Datasheet (PDF)

® RT7263B 3A, 21V 500kHz Synchronous Step-Down Converter General Description The RT7263B is a synchronous step-down regulator with an internal power MOSFET. It achieves 3A of continuous output current over a wide input supply range with excellent load and line regulation. Current mode operation provides fast transient response and eases loop stabilization. Fault condition protection includes cycle-by-cycle current limiting and thermal shutdown. An adjustable soft-start reduces the stress on the.

  RT7263B   RT7263B


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® RT7263B 3A, 21V 500kHz Synchronous Step-Down Converter General Description The RT7263B is a synchronous step-down regulator with an internal power MOSFET. It achieves 3A of continuous output current over a wide input supply range with excellent load and line regulation. Current mode operation provides fast transient response and eases loop stabilization. Fault condition protection includes cycle-by-cycle current limiting and thermal shutdown. An adjustable soft-start reduces the stress on the input source at startup. The RT7263B requires a minimal number of readily available external components, providing a compact solution. Features z z z z z z z z z z z z Wide Input Range : 4.5V to 21V Adjustable Output from 0.603V to 15V 3A Output Current 120mΩ/40mΩ Internal Power MOSFET Switch Internal Compensation Minimizes External Parts 500kHz Fixed Switching Frequency Synchronized External Clock from 300kHz to 2MHz Adjustable Soft-Start Cycle-by-Cycle Over Current Limit Thermal Shutdown Protection Small 14-Lead WDFN Package RoHS Compliant and Halogen Free Ordering Information RT7263B Package Type QW : WDFN-14L 4x3 (W-Type) Lead Plating System Z : ECO (Ecological Element with Halogen Free and Pb free) Note : Richtek products are : ` Applications z z z z Distributive Power Systems Battery Charger DSL Modems Pre-Regulator for Linear Regulators Marking Information 10 : Product Code RoHS compliant and compatible with the current requirements of IPC/JEDEC J-STD-020. Suitable for use in SnPb or Pb-free soldering processes. 10 YM DNN YMDNN : Date Code ` Simplified Application Circuit VIN CIN VCC CC RT SYNC ON/OFF SYNC EN AGND FB CSS SS GND R2 VIN BOOT RT7263B SW R1 COUT CBOOT L VOUT Copyright © 2012 Richtek Technology Corporation. All rights reserved. is a registered trademark of Richtek Technology Corporation. DS7263B-01 September 2012 www.richtek.com 1 Free Datasheet http://www.datasheet4u.com/ RT7263B Pin Configurations (TOP VIEW) VIN SW SW SW SW BOOT SYNC 1 2 3 4 5 6 7 14 13 GND 15 12 11 10 9 8 AGND GND GND VCC SS EN FB WDFN-14L 4x3 Function Pin Description Pin No. 1 Pin Name VIN Pin Function 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. 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. Bootstrap for High Side Gate Driver. Connect a 100nF or greater capacitor from SW to BOOT to power the high side switch driver. External Frequency Synchronization Input. Connect an external clock on this pin changes the switching frequency. Feedback Input. FB senses the output voltage via an external resistive voltage divider. The feedback reference voltage is 0.603V typically. Enable Control Input. Floating this pin or connecting this pin to logic high will enable the device and connecting this pin to GND will disable the device. Soft-Start Control Input. Connect a capacitor from SS to GND to set the soft-start period. Bias Supply. Decouple with 0.1μF to 0.22μF capacitor between this pin and GND. Ground. The exposed pad must be soldered to a large PCB and connected to GND for maximum power dissipation. Analog Ground. Connect this pin to the system ground in PCB layout. 2, 3, 4, 5 SW 6 7 8 9 10 11 BOOT SYNC FB EN SS VCC 12, 13, GND 15 (Exposed Pad) 14 AGND Copyright © 2012 Richtek Technology Corporation. All rights reserved. is a registered trademark of Richtek Technology Corporation. www.richtek.com 2 DS7263B-01 September 2012 F r e e D a t a s h e e t RT7263B Function Block Diagram VIN VCC EN Regulator Oscillator SYNC OC Limit Clamp Reference FB 10µA SS Error Amplifier GND 30pF + Ramp Generator Current Sense Amplifier + BOOT S Q PWM Comparator Driver R SW + + - 400k 1pF Operation The RT7263B 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 (VFB) 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 cir.


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