This is a design circuit for power supply that based on LM1578 single chip IC. The LM1578A Switching Regulator can be used to convert the already existing supply into a separate ±12V supply for powering the interface line drivers. This is the figure of the circuit.
The power supply, shown in the figure operates from an input voltage as low as 4.2V, and delivers an output of ±12V at ±40 mA with an efficiency of better than 70%. The circuit provides a load regulation of ±1.25% (from 10% to 100% of full load) and a line regulation of ±0.08%. Other notable features include a cycle-by-cycle current limit and an output voltage ripple of less than 40 mVp-p. A unique feature of this flyback regulator is its use of feedback from BOTH outputs. This dual feedback configuration results in a sharing of the output voltage regulation by each output so that one output is not left unregulated as in single feedback systems. In addition, since both sides are regulated, it is not necessary to use a linear regulator for output regulation.
[Schematic circuit source: National Semiconductor Notes]
The power supply, shown in the figure operates from an input voltage as low as 4.2V, and delivers an output of ±12V at ±40 mA with an efficiency of better than 70%. The circuit provides a load regulation of ±1.25% (from 10% to 100% of full load) and a line regulation of ±0.08%. Other notable features include a cycle-by-cycle current limit and an output voltage ripple of less than 40 mVp-p. A unique feature of this flyback regulator is its use of feedback from BOTH outputs. This dual feedback configuration results in a sharing of the output voltage regulation by each output so that one output is not left unregulated as in single feedback systems. In addition, since both sides are regulated, it is not necessary to use a linear regulator for output regulation.
[Schematic circuit source: National Semiconductor Notes]
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