Product Summary

The m51977p is an off-line primary PWM controller which is especially designed for SMPS to get the regulated DC voltage from AC power supply. As the totempole type high power-driver-circuit is intergrated in the m51977p, the m51977p can drive the MOS-FET with fast rise and fast fall output pulse. The m51977p has the functions of not only high frequency OSC and fast output drive but also current limit with fast response and high sensibility so the true fast switching regulator can be realized. Applications of the m51977p include: feed foward regulator and fly back regulator.

Parametrics

m51977p absolute maximum ratings: (1) supply voltage Vcc: 31V; (2) collector voltage Vc: 31V; (3) output current Io: ±2A (Peak) , ±0.15A (Continuous) ; (4) VF terminal voltage VVF: Vcc; (5) CLM-terminal voltage VCLM: -4 to +4V; (6) CLM+terminal voltage VCLM+: -0.3 to 4V; (7) OVP terminal voltage VOVP: Vcc; (8) DET terminal voltage VDET: 6V; (9) DET terminal input current: 5mA; (10) F/B terminal input current: -1mA; (11) T-OFF terminal input current: -2mA; (12) Power dissipation: 1.5W (Ta=25°C) ; (13) Operationg temperature Topr: -30 to +85°C; (14) storage temperature: -40 to +125°C; (15) Junction temperature Tj: 150°C.

Features

m51977p features: (1) 500kHz operation of MOS-FET; (2) Output current of ±2A; (3) fast rise time of 60ns and fast fall time of 40ns; (4) small through current owing to modified totempole dirve circuit; (5) compact and light-weight power supply; (6) small start-up current: 80μA typ.; (7) big difference betweeen start-up voltage and stop voltage makes the smoothing capacitor of the power input section small; (8) high-speed current limiting circuit using pulse-by-pulse method; (9) protection by intermittent operation of output over current; (10) over-voltage protection circuit; (11) protection circuit for output miss action at low supply voltage; (12) high-performance and highly functional power supply.

Diagrams

m51977p block diagramo