LOW COST POWER-SAVING MODE PWM CONTROLLER FOR FLYBACK CONVEBNOERS

DESCRIPTION

The UTC UC3837L is a high performance current mode PWM

controller ideally suited for low standby power. Low VDD startup

current make the power reliable on startup design and a large

value resistor could be used in the startup circuit to minimize the

standby power. At no load condition, the IC operates in

power-saving mode for lower standby power, decreasing frequency

for Higher conversion efficiency at light load condition.  

The UTC UC3837L contains protection with automatic recovery

including OLP (over load protection), OCP (cycle-by-cycle current

limiting), and UVLO (VDD over voltage clamp and under voltage

lockout).  It also provides the protections including OTP (over

temperature protection), OVP (over voltage protection) in UTC

UC3837L with  latched shut down. To protect the power MOSFET,

Gate-drive output is fixed up to 16V max.

The internal slope compensation  improves system stability at

high PWM duty cycle output. Leading-edge blanking on current

sense input removes the signal glitch, which offering minimal

external component count in the design. Excellent EMI

performance is achieved with UTC proprietary frequency hopping

technique (ZL201020615247.1) together with soft driver control.

Audio noise is eliminated due to switch frequency more than 20kHz

during operation.

The UTC UC3837L has such applications as: battery charger,

power adaptor, set-top box power supplies, ink jet printers,

open-frame SMPS.