STEP_DOWN_REGULATOR

Published:2009/7/16 20:48:00 Author:Jessie | From:SeekIC

There are several versions of the LM2575T. The device used here has an ADJ suffix, which indicates that it has an adjustable output voltage. Pin 4 connects to the inverting input of the internal error amplifier. This amplifier's noninverting input is fed from a 1.2-V reference source. A discrete potentiometer connected across the output and feeding into pin 4 enabling the output voltage to be set at any figure above 1.2 V. In this case, the potentiometer is formed by VR1 in series with resistor R1. The adjustment range provided by VR1 is from 1.2 V to a little over 16 V. Higher output voltages can be accommodated by making R1 lower in value, but a circuit of this type is mainly used where there is a large voltage difference between the input and the output. Consequently, it is unlikely to be used with output voltages of more than about 16 V. The absolute maximum input voltage is 40 V.



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