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Maxim describes various SMPS regulator topologies for battery powered systems. Isolated and non-isolated topologies are covered. This tutorial presents an overview of regulator topologies for battery-powered equipment. The discussion covers linear regulators, charge pumps, buck and boost regulators, inverters, and flyback designs. The importance of peak current is explained, and schematics of each topology are shown.

A simple stereo audio amplifier is built around two 7905 negative-voltage regulators (IC1 and IC2) and a few discrete components. The circuit will also work with other 79XX regulators if appropriate power supply is used. Regulator IC 7905 works as an amplifier for the voltages applied to common pin2 (Ground or GND). Also check the LM317 audio amplifier, another interesting circuit. The minimal voltage drop over the standard 7905 is around 2V and it depends on the output current. Feedback resistors in the IC set the gain of the channel internally. The amplifier is a class-A audio amplifier. The minimal applicable value of R3 for the regulator 7905 is 8.2 to 10 ohms per 5W. Circuit diagram : 1W Stereo Amplifier with Voltage Regulators Circuit Diagram If the required output current for LS1 is below 100 mA, the value of resistor R3 can be 33 to 51 ohms per watt. The circuit works with any load resistance (R3 in parallel with LS1 as the load) under the condition that the regulator is ...