First switching power supply working.
I have an ARM board to be powered, which draws between 0.5 and 1.5 ampere’s on 5 volt. Tried using an standard 7805 (2 ampere spec), but the system would not boot. VOut dropped to 4.5 volts and 7805 was getting to hot with +/- 24 volt VIn.
So i made an circuit based on the LM2576T-5.
Partslist:
Part | Price | |
IC1: LM2576T-5 | € 1,60 | |
L1: Inductor 100uH | € 1,45 | |
D1: SR504 | Recoverd from PC PSU | 5.0 Amps Schottky Barrier Rectifier |
C1: 470uF 35v | Reused from other project | |
C2: 3300uF 10v | Also recovered from PC PSU | |
F1: Fuse holder and 400mA | Stock, price n/a |
Input voltage is an battery+solar power supply that varies between 23-24 to 29 volts.
Working power supply (left) with active load.
Bad output: (spikes)
What happens if an normal (or to slow) diode is used:
Yellow is regulator V-OUT.
Blue line represents voltage output for load (feedback signal).
Good output:
No load:
100mA load
Borrowed lm2576 library for Eagle PCB Design from eaglecentral.ca | LM2576 circuit