Features
 Secondary side synchronous rectification
controller optimized for flyback converter
 Suitable for QR and mixed CCM/DCM fixed
frequency operation
 Wide Vcc operating voltage range 3.75 to 32 V
 CC regulation operation down to 2 V output
supported
 Very low quiescent current in low consumption
mode (160 μA)
 High-voltage sensing input for SR MOSFET
drain-source voltage (100 V AMR)
 Operating frequency up to 300 kHz
 High-current gate-drive output for N-MOSFET
 Fast turn-on with minimum delay time and
adaptive turn-off logic
 Programmable min. TON and fixed min. TOFF (3
options: SRK1000, SRK1000A, SRK1000B)
 Low consumption mode entry by primary side
burst-mode detection or by detection of SR
MOSFET conduction lower than programmed
min TON
 SOT23-6L package

Applications
 Battery chargers / quick chargers
 Adapters
 USB power delivery (profile 3)

Description
The SRK1000 is a controller intended for
secondary side synchronous rectification (SR) in
flyback converters, suitable for operation in QR
and mixed CCM/DCM fixed frequency circuits.
It provides a high-current gate-drive output,
capable of driving N-channel Power MOSFETs.
The control scheme of this IC is such that the SR
MOSFET is switched on as soon as current starts
flowing through its body diode and it is then
switched off as current approaches zero.
The fast turn-on, with minimum delay, and the
innovative adaptive turn-off logic allow
maximizing the conduction time of the SR
MOSFET and eliminating the effect of parasitic
inductance in the circuit.
The device enters low consumption mode when it
detects primary controller burst-mode operation,
or when the SR MOSFET conduction becomes
lower than the programmed minimum TON. In this
way, converter efficiency improves at light load
where synchronous rectification is no longer
beneficial.
After the converter restarts switching or the IC
detects that the current conduction in the rectifiers
has increased 20% above the min TON
programmed value, the IC exits low consumption
mode and resumes switching operation.