A Product Line of Diodes Incorporated APR34309/A SECONDARY SIDE SYNCHRONOUS RECTIFICATION SWITCHER Description Pin Assignments APR34309/A is a secondary side Combo IC, which combines an N- (Top View) Channel MOSFET and a driver circuit designed for synchronous rectification (SR) in DCM operation. It also integrates output voltage detect function for primary side control system. DRISR GND 8 1 The N-Channel MOSFET has been optimized for low gate charge, low R , fast switching speed and body diode reverse recovery DS(ON) VDET GND 2 7 performance. AREF GND 3 6 The synchronous rectification can effectively reduce the secondary side rectifier power dissipation and provide high performance solution. VCC DRAIN 4 5 By sensing MOSFET drain-to-source voltage, APR34309/A can output ideal drive signal with less external components. It can provide high performance solution for 5V output voltage application. Note: The DRAIN pin of internal MOSFET is exposed PAD, which is at the bottom of IC (the dashed box). The secondary current should flow from GND(pin 6,7,8) to Same as AP4341, APR34309/A detects the output voltage and this exposed PAD. provides a periodical signal when the output voltage is lower than a certain threshold. By fast response to secondary side voltage, SO-8EP APR34309/A can effectively improve the transient performance of primary side control system. The APR34309/A is available in SO-8EP package. Applications Adapters/Chargers for Cell/Cordless Phones, ADSL Modems, MP3 and Other Portable Apparatus Features Standby and Auxiliary Power Supplies Synchronous Rectification for DCM Operation Flyback Eliminate Resonant Ring Interference Fast Detector of Supply Voltages Fewest External Components Totally Lead-free & Fully RoHS Compliant (Notes 1 & 2) Halogen and Antimony Free. Green Device (Note 3) Notes: 1. No purposely added lead. Fully EU Directive 2002/95/EC (RoHS) & 2011/65/EU (RoHS 2) compliant. 2. See VDET A Product Line of Diodes Incorporated APR34309/A Pin Descriptions Pin Number Pin Name Function 1 DRISR Synchronous rectification MOSFET drive. Synchronous rectification sense input and dynamic function output, connected to DRAIN 2 VDET through a resistor. Program a voltage reference with a resistor from AREF to GND, to enable synchronous 3 AREF rectification MOSFET drive signal. 4 VCC Power supply, connected with system output. 5 DRAIN Drain pin of internal MOSFET. The Drain voltage signal can obtain from this pin. 6, 7, 8 GND Source pin of internal MOSFET, connected to Ground. Drain pin of internal MOSFET. The secondary current should flow from GND (pin 6.7.8) Exposed PAD DRAIN to this DRAIN pad. Functional Block Diagram VCC 4 V REF I OVP Dynamic Integrator OVP (V -V )*t DET CC ONP I AREF Counter t ONPDET 3 AREF OSC 1 SRDRIVER DRISR 6,7,8 GND 5, EP DRAIN 2 VDET 2 of 12 APR34309/A June 2015 Diodes Incorporated www.diodes.com Document number: DS37412 Rev. 3 - 2 NEW PRODUCT