UNISONIC TECHNOLOGIES CO., LTD
UC3837L
CMOS IC
LOW COST POWER-SAVING
MODE PWM CONTROLLER
FOR FLYBACK
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DESCRIPTION
The UTC UC3837L is a high performance current mode PWM
SOT-26
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.
FEATURES
* UTC proprietary frequency hopping technology for Improved EMI * Programming BNO/Line OVP for higher
performance.
security
* Power-saving mode for high light-load and standby efficiency
* Soft Start
* Dynamic peak current limiting for constant output power
* Built-in synchronized slope compensation
* OLP with automatic recovery
* Fixed switch frequency 65kHz
* Gate output voltage clamped at 16V
* Low start-up current
* Cycle-by-cycle current limiting
* Under voltage lockout (UVLO)
* Few external components required
* OTP and OVP ( in UTC UC3837L with latch shut down)
* VDD clamp for higher security
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