I am using the MP4323 in a gas generator control circuit. VOut is set to 5v and the load is a 5v hobby sized servo, an MCU, a CAN ic, an ADC ic, and a few other small components. The MCU is fed by a 3v3 LDO while the other IC’s receive the 5v from the MP4323. The main current draw from everything minus the servo is typially around 150-200ma. The servo draws marginal power when not moving but can spike up to around 2400ma if it stalls.
The problem i am having is my CAN Ic, mcp2562, kept dying on me. So i scoped the 5v power supply to see if that was the cause and noticed that when I engage the generator starter motor, the battery voltage drops to ~8 volts and then slowy creeps closer to 11v. When this happens there is a spike on the output of the MP4323, usually around 6.5-7.5v but i saw a few spikes around Vin level(nominal 12v).
I followed the diagram in the datasheet using component sizes for a 5v, 3a load to give me some buffer. That is 4.7uf x 2 and 0.1uf x 2 input capacitors, 22uf x2 output capacitors, and 4.7uh molded inductor Fsw is 2.2mhz. i am using name brand quality x7r MLCC caps. I also have a bulk electrolytic of 1000uf right at the Vin of my PCB.
What would cause these short voltage spikes that are frying my CAN transceivers? Most of the time the current draw from the MP4323 is low, but the max can be close to 3a so I chose those values. I tried to keep feedback trace away from the switching node. Any help would be appreciated.
