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UC3873B Datasheet








The  UC3873B 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  UC3873B contains protection with automatic recovery

including OLP (over load protection), programming OTP (over temperature protection), OVP (over voltage protection), UVLO (VDD over voltage clamp and under voltage

lockout).To protect the power MOSFET, Gate-drive output is fixed up to 16V max. The UC3873B contains protection

OCP (cycle-by-cycle current limiting).

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  UC3873B  has such applications as: battery charger, power adaptor, set-top box power supplies, ink jet

printers, open-frame SMPS.





* 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

* OLP,OVP and VDD clamp for higher security

* -500/+500mA gate driver

* Programming OTP 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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