I am trying to decide between using the built in PMU or using an external PMIC to generate chip voltages for an i.MX6SL.
The Reference Manual for the i.MX6SL states that the internal PMU can be used to simplify the power distribution network for a design, but to get optimal power the PMU should not be used. I would like to understand why this is.
I understand that if the PMU is to generate several different voltages then I will have to supply at least the MAX of those voltages to the PMU. The PMU will then lose some energy in the switchers/LDOs and that could decrease power efficiency. Is that what the Manual is warning about? because if so, wouldn't the same (or similar) energy be lost using an external (non-PMU) switcher/LDO? Also, can I still use dynamic voltage scaling if the voltages are generated outside of the chip?
Any information on this would be appreciated, Thanks!