The typical application circuit of the MP6604A datasheet shows a 50 mOhm series resistor on each power-ground pin. The schematic of the corresponding eval board has 100 mOhm resistors in the same place. The datasheet does not describe a requirement or even a recommendation for these resistors, and there is no mention of them anywhere else.
Please clarify the role and purpose of these resistors.
Hi,
Thank you for the question. In short, the PGND resistors are not a functional requirement.
They have three main purposes:
Damping: 50–100 mΩ in series with PGND adds minimal loss (internal R_DS(ON) is ~135–150 mΩ) while suppressing high-frequency ringing on the power-ground rails during the fast switching transients.
Eval-board test convenience: 100 mΩ gives a sense point for easy current measurement without adding a separate probe.
PGND-to-signal-ground isolation: a small series element limits ground-bounce coupling into the OCP/sensing references.
In a layout with short, wide PGND traces and adequate decoupling (as the datasheet recommends for copper/via placement), trace parasitics already provide similar damping. Omitting the discrete resistors should be fine.
Thanks,
Mason