RT9209/RT9209A pdf datasheet (

The RT9209/A is a single power supply PWM DC-DC
converter controller designed to drive N-MOSFET in a
synchronous buck topology. The IC integrates the control,
output adjustment, monitoring and protection functions into
a small 8-pin package.
The RT9209/A uses an internal compensated voltage mode
PWM control for simple application design. An internal
0.8V reference allows the output voltage to be precisely
regulated to low voltage requirement. A fixed 260kHz/
400kHz oscillator reduce the component size for saving
board area.
The RT9209/A future a enable control pin to shutdown PWM
switching and a 90% power good flag indicator. The FB
pin under voltage detection function monitor the output
short circuit which trigger a three time hiccup sequence
to latch off the chip function.