On 9 November 2016 at 01:33, Michael Mrozek <EvilDragon@openpandora.org> wrote:
Hm. VDD_MPU is being handled by the PALMAS automatically, as far as I know.
It measures the voltage directly at the OMAP5 and adjusts it, so that should be fine.

It's not that simple.

The remote sensing of VDD_MPU allows palmas to compensate mean voltage drop, but it is not going to deal with transients. Even if it could measure and compensate fast enough (it can't), the loop inductance of the power distribution net would probably prevent it from succeeding. (Such an aggressive control loop would also be prone to instability.)

Dealing with transients is still the job of decoupling caps as usual. TI gives quite a bit of guidance on the power distribution nets in general (sections 7.2.1-7.2.4, 7.3 of swps051k) and decoupling caps in particular (e.g. section 7.3.2-7.3.4).

Matthijs