Hello,
I designed a small embedded board powered by a buck converter. The MCU runs normally, but when the output load changes quickly, the controller sometimes resets unexpectedly.
The reset line is pulled high with 10k, and there is basic decoupling near the MCU.
Questions:
Could output ripple or transient voltage dip trigger brownout reset?
Should I focus on compensation tuning or add more bulk capacitance first?
On the PCB side, how critical is minimizing the switching loop area around the buck converter?
Yes … its posssible … Fast load changes can cause:
Voltage dips (transients) on the MCU rail
Brief drops below the brownout threshold … can cause reset
Ground bounce that momentarily shifts the reset/VDDA reference
Compensation tuning or more bulk capacitance first?
Start with bulk … decoupling … then check compensation.
Add bulk capacitance near the load (100 uF capacitor)
Ensure low-ESR caps close to MCU supply pins
Verify regulator output capacitor matches datasheet requirements
PCB: how critical is switching loop area?
Extremely critical … Keep switching loop area as small as possible
Place input cap very close to switch/diode
Use solid ground plane … if you are using multilayer pcb … I would recommend to use seperate gnd and power planes, read this guide: Routing Layers and Ground Planes & Power Planes - Engineering Technical - PCBway
Keep power stage physically separated from MCU/analog section
This is a power integrity problem under transient load, not just a reset pin issue. Improve local capacitance first, then verify regulator stability, and ensure tight PCB layout of the buck converter to prevent noise and dips.
