Hi All,
I'm building my first voltage regulator circuit and have run up against a problem you guys might have some clue about. I'm using an LM2576 to power an arduino and some other bits (LCD display) which all together runs at around 100mA @ 5v. While developing I've been using between 1 and 3 PP3 9v batteries in series as the source with no problem what so ever.
However I've now hooked up the circuit to my final power supply which is a 42v 10Ah battery and as soon as I plugged it got a popping sound and all the magic smoke escaped....
(btw the board is fused with a 1A fuse and this did blow - good job too!)
After some investigation I can see that the arduino board is fried - no visual damage but when I now power it up it takes ~150mA (9v PP3 battery power again so that is probably the limit). The big clue that there is a problem on the arduino board is the LED's light and the go out after 1/4 of a second or so. (even with the ATmega 328 removed)
After I'd blow the Arduino I check the LM2576 and it still seems to be working (steady 5v output) when connected to a single 9v PP3 battery , but I've not check what it outputs when connected to the 42v battery.
I suspect that I'm having an issue with inrush current, although my knowledge here gets a bit sketchy!
The LM2576 circuit is just the basic one as suggested in the data sheet with a relatively big cap (2200uF from memory) since my current draw is so low (~100mA). I've connected the ON/OFF pin straight to ground but have read last night that it might be worth using this to delay switch-on for the output to give the VR some time to settle.
All comments welcome
sal_park