About the capacitor on PMID of BQ25910,Ti suggest us to select 10uf . is it possible to select a small one ? how about 2.2uf ?
i know the capcacior on PMID pin is the input capacitor of charger(buck) circuit ,also it is the output capacitor of the boost circuit (OTG mode).
my question is .
a) about the boost mode , small output capcitor mean higher RH zero , also it mean it will be higher than 10*fcross.
so the 2.2uf is ok for boost mode . am i right ?
b) about the charger circuit (buck mode), seems the capacitor on PMID will lead a RC circuit (the R is the Ron of the mosfet on input side ) in input current loop , it is related with the stability of input current regulation loop .
is it OK to reduce it ?
c) if the input capacitor is too small, will it lead a unstable for CCM during charging ?
it is mean the circuit can't mantain the Volt-second conservation in single PWM period ,so there will be a low frequncy envelope line on output .
if the scan frequncy of oscilloscope is high enough , we can see more detail with a short time ,the noise will only be switch ripple .
if the scan frequncy of oscilloscope is slow , we will see the wave with a longer time ,than we will find the envelope line ,and the output nosie will be higher than before (the scan frequncy of oscilloscope is high enough)
d ) the capacitor will increasing the input ripple .which mean the input current DPM will be more easy to be actived .
e) is there any other influnce on reducing the capacitor of PMID ?