DESCRIPTION

M51995 is the primary switching regulator controller which

is especially designed to get the regulated DC voltage

from AC power supply.

This IC can directly drive the MOS-FET with fast rise and

fast fall output pulse.

Type M51995 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.

It has another big feature of current protection to short

and over current, owing to the integrated timer-type protec-

tion circuit, if few parts are added to the primary side

The M51995 is equivalent to the M51977 with externally re-

settable OVP(over voltage protection)circuit.

FEATURES

® 500kHz operation to MOS FET

« Output current - +2

+ Output rise time 60ns, fall time 40ns

+ Modified totempole output method with small through

current

® Compact and light-weight power supply

+ Small start-up current ~~ 90uA typ.

- Big difference between “start-up voltage” and “stop

voltage” makes the smoothing capacitor of the power

input section small.

Start-up threshold 16V, stop voltage 10V

+ Packages with high power dissipation are used to with-

stand the heat generated by the gate-drive current of

MOS FET.

16-pin DIP, 20-pin SOP 1.5W (at 25°C)

® Simplified peripheral circuit with protection circuit and

built-in large-capacity totempole output

- High-speed current limiting circuit using pulse-by-

pulse method (Two systems of CLM+pin, CLM—pin)

+ Protection by intermittent operation of output over cur-

rent SERRE -++- Timer protection circuit

+ Over-voltage protection circuit with an externally re-

settable latch (OVP)

+ Protection circuit for output miss action at low supply

voltage (UVLO)

© High-performance and highly functional power supply

+ Triangular wave oscillator for easy dead time setting