RT8055GQW

® RT8055 3A, 2MHz, Synchronous Step-Down Converter General Description Features The RT8055 is a high efficiency synchronous, step-down DC/DC converter. Its input voltage range is from 2.6V to 5.5V and provides an adjustable regulated output voltage from 0.8V to 5V while delivering up to 3A of output current. z set by an external resistor. The 100% duty cycle provides low dropout operation extending battery life in portable systems. Current mode operation with external compensation allows the transient response to be optimized over a wide range of loads and output capacitors. z z z z z z z Applications z The RT8055 is operated in forced continuous PWM Mode which minimizes ripple voltage and reduces the noise and RF interference. The RT8055 is available in the WDFN-10L 3x3 and SOP-8 (Exposed Pad) packages. z z z z z z Ordering Information RT8055 Package Type QW : WDFN-10L 3x3 (W-Type) SP : SOP-8 (Exposed Pad-Option 2) Lead Plating System G : Green (Halogen Free and Pb Free) Z : ECO (Ecological Element with Halogen Free and Pb free) Low RDS(ON) Internal Switches : 100mΩ Ω Programmable Frequency : 300kHz to 2MHz No Schottky Diode Required 0.8V Reference Voltage Allows for Low Output Voltage Forced Continuous Mode Operation 100% Duty Cycle Operation Input Over Voltage Protection RoHS Compliant and Halogen Free Portable Instruments Battery-Powered Equipment Notebook Computers Distributed Power Systems IP Phones Digital Cameras 3G/3.5G Data Card Pin Configurations (TOP VIEW) SHDN/RT GND LX LX PGND 1 2 3 10 9 GND The internal synchronous low on-resistance power switches increase efficiency and eliminate the need for an external Schottky diode. The switching frequency is z High Efficiency : Up to 95% 4 5 8 7 6 11 COMP FB VDD PVDD PVDD WDFN-10L 3x3 Note : Richtek products are : ` RoHS compliant and compatible with the current requirements of IPC/JEDEC J-STD-020. ` Suitable for use in SnPb or Pb-free soldering processes. SHDN/RT GND 2 LX 3 PGND 4 GND 8 COMP 7 FB 6 VDD 5 PVDD 9 SOP-8 (Exposed Pad) Copyright © 2012 Richtek Technology Corporation. All rights reserved. DS8055-05 November 2012 is a registered trademark of Richtek Technology Corporation. www.richtek.com 1 RT8055 Marking Information RT8055GQW RT8055GSP JN= : Product Code RT8055GSP : Product Number RT8055 GSPYMDNN YMDNN : Date Code JN=YM DNN YMDNN : Date Code RT8055ZQW JN : Product Code YMDNN : Date Code JN YM DNN Typical Application Circuit VIN 5V L1 2µH CIN 22µF PVDD RT8055 VDD C1 0.1µF ROSC 180k VOUT 3.3V/3A LX R1 75k COUT 22µF x 2 FB SHDN/RT R2 24k COMP RCOMP 30k GND PGND CCOMP 470pF Table 1. Recommended Component Selection VOUT R1 (kΩ) R2 (kΩ) R COMP (kΩ) CCOMP (nF) L1 (μH) COUT (μF) 3.3 75 24 30 0.47 2.2 22 x 2 2.5 51 24 27 0.47 2.2 22 x 2 1.8 30 24 22 0.47 2.2 22 x 2 1.5 21 24 18 0.47 2.2 22 x 2 1.2 12 24 15 0.47 1.0 22 x 2 1.0 6 24 13 0.47 1.0 22 x 2 Copyright © 2012 Richtek Technology Corporation. All rights reserved. www.richtek.com 2 is a registered trademark of Richtek Technology Corporation. DS8055-05 November 2012 RT8055 Functional Pin Description Pin No. WDFN-10L 3x3 SOP-8 1 1 Pin Name Pin Function Shutdown Control or Frequency Setting Input. Connect a SHDN/RT resistor to ground from this pin sets the switching frequency. Force this pin to VDD or GND causes the device to be shut down. Signal Ground. All small-signal components and compensation 2, components should be connected to this ground, which in turn 2, GND 11 (Exposed Pad) 9 (Exposed Pad) connects to PGND at one point. The exposed pad must be soldered to a large PCB and connected to GND for maximum power dissipation. Internal Power MOSFET Switches Output. Connect this pin to 3, 4 3 LX 5 4 PGND 6, 7 5 PVDD 8 6 VDD 9 7 FB 10 8 COMP the inductor. Power Ground. Connect this pin close to the negative terminal of CIN and COUT . Power Supply Input. Decouple this pin to PGND with a capacitor. Signal Supply Input. Decouple this pin to GND with a capacitor. Generally, VDD is equal to PVDD. Feedback Pin. This pin receives the feedback voltage from a resistive divider connected across the output. Error Amplifier Compensation Point. The current comparator threshold increases with this control voltage. Connect external compensation elements to this pin to stabilize the control loop. Function Block Diagram SHDN/RT PVDD ISEN SD OSC Slope Comp. COMP 0.8V FB EA Output Clamp OC Limit Internal Soft Star Driver LX Control Logic 0.7V NISEN OTP POR PGND N-MOSFET ILIM 0.4V VREF GND VDD Copyright © 2012 Richtek Technology Corporation. All rights reserved. DS8055-05 November 2012 is a registered trademark of Richtek Technology Corporation. www.richtek.com 3 RT8055 Absolute Maximum Ratings z z z z z z z z z z (Note 1) Supply Input Voltage, VDD, PVDD ---------------------------------------------------------------------------- −0.3V to 6.5V LX Pin Switch Voltage -------------------------------------------------------------------------------------------- −0.3V to (PVDD + 0.3V)