I have built a pcb that uses a (D-Sun) 3 Amp SMPS. Little cheap things found everywhere on ebay etc.
I've used many in the past without incident and they tend to be very good for up to 1.5 Amps. Low quiescent current and very cheap.
without the SMPS connected I am able to upload to the mcu (atmega328pb) via the program header and everything works fine and done
blink tests on random pins.
There is 12V (lead battery) to power the SMPS which goes through a PMOS -ME12P04 (reverse polarity protection) and is shared with a HS switch, and there is no problem with that.
All grounds are shared.
The SMPS (@4.1v) is used to power the MCU and goes through another HS switch for sensors etc.
When i connect the SMPS it appears to short the MCU and gets very hot and the output voltage bounces 400mv
first chip fused with 160 Ohm short second with 2.5.
Connecting the SMPS to a small motor and runs without a problem - steady output on 50mA, even with 7 ohm resistor
only 10-20mV drop.
The only thing different to what i have done in the past is use a different PMOS, but that looks all in spec.
Could it be a problem between the PMOS and SMPS switching speeds? or low current? or ground issues?
I got a few of these SMPS but they all the same batch So i'm asking here if anyone has had similar experience or Knowledge before I start cooking again!
Thanks for looking.
I've used many in the past without incident and they tend to be very good for up to 1.5 Amps. Low quiescent current and very cheap.
without the SMPS connected I am able to upload to the mcu (atmega328pb) via the program header and everything works fine and done
blink tests on random pins.
There is 12V (lead battery) to power the SMPS which goes through a PMOS -ME12P04 (reverse polarity protection) and is shared with a HS switch, and there is no problem with that.
All grounds are shared.
The SMPS (@4.1v) is used to power the MCU and goes through another HS switch for sensors etc.
When i connect the SMPS it appears to short the MCU and gets very hot and the output voltage bounces 400mv
first chip fused with 160 Ohm short second with 2.5.
Connecting the SMPS to a small motor and runs without a problem - steady output on 50mA, even with 7 ohm resistor
only 10-20mV drop.
The only thing different to what i have done in the past is use a different PMOS, but that looks all in spec.
Could it be a problem between the PMOS and SMPS switching speeds? or low current? or ground issues?
I got a few of these SMPS but they all the same batch So i'm asking here if anyone has had similar experience or Knowledge before I start cooking again!
Thanks for looking.