RT5797B 3A, 1MHz, 6V CMCOT Synchronous Step-Down Converter General Description Features Efficiency Up to 95% The RT5797B is a high efficiency synchronous step- R 100m HS / 70m LS DSON down DC/DC converter. Its input voltage range is from V Range 2.7V to 6V IN 2.7V to 6V and provides an adjustable regulated output V 0.6V with 1% Accuracy at 25C REF voltage from 0.6V to 3.4V while delivering up to 3A of CMCOT Control Loop Design for Best output current. Transient Response, Robust Loop Stability with The internal synchronous low on-resistance power Low-ESR (MLCC) C OUT switches increase efficiency and eliminate the need for Soft-Start 1.2ms an external Schottky diode. The Current Mode Constant-On-time (CMCOT) operation with internal Applications compensation allows the transient response to be STB, Cable Modem, & xDSL Platforms optimized over a wide range of loads and output LCD TV Power Supply & Metering Platforms capacitors. The RT5797B is available in the WDFN-8L General Purpose Point of Load (POL) 2x2 package. Pin Configurations Ordering Information (TOP VIEW) RT5797B Package Type 1 8 FB SGND QW : WDFN-8L 2x2 (W-Type) 2 7 PG EN VIN 3 6 LX 9 Lead Plating System PGND 4 5 NC G : Green (Halogen Free and Pb Free) WDFN-8L 2x2 UVP Option H : Hiccup L : Latched-Off Marking Information Note : RT5797BLGQW 2S : Product Code Richtek products are : W : Date Code RoHS compliant and compatible with the current 2SW requirements of IPC/JEDEC J-STD-020. Suitable for use in SnPb or Pb-free soldering processes. RT5797BHGQW 2T : Product Code W : Date Code 2TW Simplified Application Circuit RT5797B L V IN VIN LX V OUT C IN C R1 EN OUT FB PG SGND PGND R2 Copyright 2016 Richtek Technology Corporation. All rights reserved. is a registered trademark of Richtek Technology Corporation. DS5797B-01 February 2016 www.richtek.com 1 PGNDRT5797B Functional Pin Description Pin No. Pin Name Pin Function Feedback Voltage Input. An external resistor divider from the output to GND, 1 FB tapped to the FB pin, sets the output voltage. Power Good Indicator. The output of this pin is an open-drain with external pull-up 2 PG resistor. PG is pulled up when the FB voltage is within 90%, otherwise it is LOW. 3 VIN Supply Voltage Input. The RT5797B operates from a 2.7V to 6V input. 4, 9 Power Ground. The exposed pad must be soldered to a large PCB and connected PGND (Exposed Pad) to PGND for maximum power dissipation. 5 NC No Internal Connection. 6 LX Switch Node. 7 EN Enable Control Input. 8 SGND Signal GND. Function Block Diagram EN VIN UVLO Shut Down Control LX Ton OTP VIN Error Comparator Amplifier FB - Logic + + Control Driver LX V REF - R C C COMP Current Limit GND Detector + Current LX - Sense PG Copyright 2016 Richtek Technology Corporation. All rights reserved. is a registered trademark of Richtek Technology Corporation. www.richtek.com DS5797B-01 February 2016 2