HL9701 Secondary-Side Synchronous Rectifier Controller for Flyback Converters

Feature
▪ Compatibility of Continuous Conduction Mode (CCM), 
Quasi-Resonant (QR) and Discontinuous Conduction 
Mode (DCM)
▪ Wide Input Voltage Range up to 30V
▪ Optimized SR Gate turn-off Threshold Control
▪ Proprietary CCM SR Turn-off Control Algorithm
▪ Minimized SR Turn-on/off Propagation Delay
▪ SR MOSFET Gate passive clamp
▪ Low Power Saving Mode
▪ Small Footprint with SOT-23 6 Pin Package
Description
HL9701 is a secondary-side synchronous rectifier (SR) 
controller for isolated flyback converters. By Implementing 
proprietary turn-off control algorithm, HL9701 can reliably 
support discontinuous conduction mode (DCM), QuasiResonant (QR) and continuous conduction mode (CCM) 
operation, which will help to design robust flyback 
converters. The SR turn-off threshold control optimizes 
the body diode conduction of SR MOSFET while 
guaranteeing stable and robust SR operation against 
noise and disturbance caused by the circuit parasitic.
HL9701 integrates a 30V rated input voltage LDO along 
with Low Vin under-voltage lockout (UVLO) voltage, which 
allows wide power supply output voltage range.
HL9701 supports high side or low side SR MOSFET 
placement which allows customer to design the power 
supply system with flexibility. HL9701 is available in a 
space-saving SOT23-6 package.