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UC3837 Datasheet

LOW COST POWER-SAVING  MODE PWM CONTROLLER  FOR FLYBACK CONVERTERS
 
 
 
DESCRIPTION
 
 
The UC3837 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 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 UC3837 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 performance. 
* 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
* OTP,OLP,OVP and VDD clamp for higher security
* Programming BNO for higher security
* Fixed switch frequency 65kHz
* Gate output voltage clamped at 15V
* Low start-up current
* Cycle-by-cycle Current Limiting
* Under voltage lockout (UVLO)
* Few external components required
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