Description

M51996A 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 and with a large-drive totempole output. Type M51996A 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. The M51996A is equivalent to the M51978 with externally re-settable OVP (over voltage protection) circuit.

Features

• 500kHz operation to MOS FET

• Output current : ±1 A

• Output rise time 60 ns, fall time 40 ns

• Modified totempole output method with small through current

• Compact and light-weight power supply

   -Small start-up current : 100 µA typ.

   -Big difference between “start-up voltage” and “stop voltage” makes the smoothing capacitor of the power input section small.

   -Start-up threshold 16 V , stop voltage 10 V

   -Packages with high power dissipation are used to with-stand the heat generated by the gate-drive current of MOS FET.

   -14-pin DIP, 16-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 (CLM+pin)

    -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

   -SOFT start function by expanding period

Application

Feed forward regulator, fly-back regulator

• Supply voltage range: 12 to 30 V

• Operating frequency: less than 500 kHz

• Oscillator frequency setting resistance

• T-ON pin resistance

   -RON: 10 k to 75 kΩ

• T-OFF pin resistance

   -ROFF: 2 k to30 kΩ