M51995AP/AFP

Switching Regulator Control

Description

M51995A 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 M51995A 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 protection circuit, if few parts are added to the primary side.

The M51995A is equivalent to the M51977 with externally re-settable OVP (over voltage protection) circuit.

Features

• 500 kHz operation to MOS FET

 Output current : ±2 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 : 90 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. 16-pin DIP, 20-pin SOP 1.5 W (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 system of CLM+pin, CLM−pin)

 Protection by intermittent operation of output over current : 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

Application

Feed forward regulator, fly-back regulator

Recommended Operating Conditions

• Supply voltage range: 12 to 36 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 to 30 kΩ

Absolute Maximum Ratings

Notes:

1. “+” sign shows the direction of current flow into the IC and “−” sign shows the current flow from the IC.

2. This terminal has the constant voltage characteristic of 6 to 8 V, when current is supplied from outside. The maximum allowable voltage is 6 V when the constant voltage is applied to this terminal. And maximum allowable current into this terminal is 5 mA.

3. The low impedance voltage supply should not be applied to the OVP terminal.

Block Diagram

Pin Arrangement

Stock Offer (Hot Sell)

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