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AC-DC Power Adapter With Current Boost Regulator

This 5V regulator circuit provides 5A load current capability, well above the current limit of the linear regular component itself. This is thanks to the load sharing role of the bypass PNP transistor.

The circuit is shown with a household 120 V. AC input, with a transformer and rectifier circuit, attempting to approximate a 12V automotive input voltage level. The design is based on an example application circuit shown in Figure 11 of the On Semiconductor Datasheet MC7800/D, November 2014 - Rev. 27. This executable design can be used to assess line and load transients, efficiency, PSRR vs. Frequency, etc. It can also be used for selecting the peripheral circuit components to achieve the desired performance.

See also for a lower power level circuit.

Darrell's picture




Joined November 6, 2013
Design added Monday, August 24, 2015 | 12:59 pm PDT


Furqan Aziz's picture

Excellent Model

yobenere hinzams's picture


DT Mai's picture

hello , and thanx a lot .
I just want to ask you about the mechanism of the current transformer .
Vielen dank

Darrell's picture

What would you like to know about the transformer?

DT Mai's picture

i am not sure , how I can that simulate . current Transformer and particularly Voltage transformer . thank you again . VG

Darrell's picture

Find transformer-related designs by looking for tags:

You might find it helpful to look at online resources for transformer theory. Try this site:


DT Mai's picture

thanx a lot .