amp variable output switching regulator lm195

This circuit is the variable output switching regulator for general purpose applications. An LM105 positive regulator is used as the amplifier-reference for the switching regulator. Positive feedback to induce switching is obtained from the LM105 at pin 1 through an LM103 diode. The positive feedback is applied to the internal amplifier at pin 5 a
amp variable output switching regulator lm195 - schematic

nd is independent of supply voltage. This forces the LM105 to drive the pass devices either on  or off,  rather than linearly controlling their conduction. Negative feedback, delayed by L1 and the output capacitor, C2, causes the regulator to switch with the duty cycle automatically adjusting to provide a constant output. Four LM195`s are used in parallel to obtain a 6 amp output since each device can only supply about 2 amps. Note that no ballasting resistors are needed for current sharing. When Q1 turns on  all bases are pulled up to V+ and no base current flows in the LM195 transistors since the input PNP`s are reverse biased.

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