1 Description

The iW873 is a high performance synchronous rectifier controller with integrated MOSFET and driver for flyback

converters operating at discontinuous conduction mode. It emulates the diode rectifier at the secondary side of the

flyback to reduce conduction loss. The iW873 determines the timing of the driver by sensing the voltage across the

RDS(ON) of the built-in MOSFET to achieve lossless sensing. Proprietary digital adaptive turn-off control technology

is used to minimize the turn-off deadtime of the synchronous rectifier so that the parallel Schottky diode required by

conventional synchronous rectifiers can be eliminated. The integrated driver has strong driving capability for high

efficiency. The operating power consumption of the controller excluding the driver is less than 4mW at no load to achieve

the ultra-low no-load power consumption for 5V applications. The iW873 integrates a pulse linear regulator to maintain

the operation of the synchronous rectifier at low system output voltage when the system is operating in constant current

(CC) mode.

2 Features

● Integrated 60V power MOSFET

● Digital adaptive turn-off control minimizes dead-time

and eliminates the parallel Schottky diode

● Integrated pulse linear regulator (PLR) allows SR

operation at low system output voltage down to 2.4V in

typical 5V, 2A USB charger applications with iW873-00

● Wide VIN pin operating voltage up to 25V

● Intelligent low power management achieves ultra-low

no-load operating current

● Lossless MOSFET VDS sensing for SR timing control

● 8-pin SOIC package