Power supply 0,3-29V 4,8A 3,3/5V 0,8A(step down)

[Vermes]

This power supply has two outputs, main output adjustable by the microcontroller in range from 0,3 to 29V 4,8A and the auxiliary 3,3/5V 0,8A (not monitored) available from one socket. Both stabilizers are step down type and have separable outputs.
Power supplies protection systems

• adjustable current limiter
• fuse
• short circuit protection and overvoltage (set programmatically) in the main stabilizer
• the auxiliary stabilizer has an self reset electronic fuse set to 0,8A. (Reset every 3 seconds with LED signalization)

Main functions of the power supply are controlled by an encoder and control buttons of switch type. The power supply has a function of output voltage tracking. The change in voltage on the display corresponds directly to voltage change at the output. In normal mode, voltage regulation is done by pressing the knob, then adjust and approve the changes by pressing the knob again. This way of regulation protects against accidental change of voltage by turning the knob encoder coincidental.
Ripple voltage at the output is consistent with the application note of LM2576 circuit used for the construction of the main stabilizer – 20 to 50mV at 12V/3A. Because of LM2576 max current (3A) there is an additional transistor keyer connected to the original in a Darlington circuit and two comparators that are used to control this from the microcontroller.
The whole device is controller by Atmega chip with 12-bit A/D and D/A converters. There s no need of cooling the circuit heat sink. After 40 minutes operation with load 15V 4.6A the heat sink temperature was 59 Celsius degrees, 46 degrees at 3A, 37 degrees at 2A.
Many elements were used from home electronic equipment: computer and video housing, two transformers, knob, relays, switches, radiator, encoder and other RCL elements.



Link to original thread (some useful attachments) – Zasilacz 0,3-29V 4,8A 3,3/5V 0,8A(step down) ster. Cyfr.