# Circuit Testing failed (Reverse polarity and Buck-Converter)

Hello guys,

today I tested my circuit. Its a simple Reverse Polarity Protection Circuit with a Buck-Converter. As I supplied voltagae to my circuit, everything was well (3.5V output). Going higher with the voltage was okay, too. Until I got to ~30V. Then my power supply gone into current limitation.

I think my TVS Diode (which I choosed too small..) gone to Breakdown Volatge and caused a short circuit (is that possible?). I Supplied voltage only to the pins of the Buck but its still not working, so I think something destroyed the buck but exactly what?

EDIT: With "the buck dont work" I mean, when I supply voltage to my circuit, my power supply goes into current limitation because the circuit wants to drain a lot of current. So if I dont supply from J1 and J5 and supply the IC pins of the buck directlyy its the same failure.

Datasheets: Buck

PMOS

Bipolar TVS

Schottky

Zener

• not going to work unless you connect bat+ – Jasen Feb 28 '18 at 10:35
• I only connect Bat+ and Bat- – Fatih Y Feb 28 '18 at 10:44
• not what the digram shows. – Jasen Feb 28 '18 at 10:44
• Now you know it. – Fatih Y Feb 28 '18 at 10:46
• C1 is 6 to 10 times bigger than the examples in the data-sheet – Jasen Feb 28 '18 at 10:57