For the MP2384 MPSmart model, I added my PDN model between the MP2384 output and my load. I’m noticing that the output undershoot is worse at the load compared to output of the regulator. What could have caused this? Would sensing at the load help with this?
PCB PDN contains ESR, ESL, and parasitic capacitance that will slow down the transient response at the load. Sensing at the load will help compensate for the DC voltage drop due to the PCB ESR. One way to improve the transient undershoot at the load is to add local bypass capacitor with low ESR and low impedance at high frequencies of interest. This local bypass will help source the front end of the load step current as the buck converter sourcing capability is being impeded by the PCB ESR and ESL.