I’m working with PMIC ACT88422 and I need a big capacitance, above 100uF on Buck 4, when the output is activated it enters in ILIM shut down, is there a workaround that allow me to charge these capacitances?
Yes charging a big value capacitor can trigger the Ilim shut down, on a components point of view you can evaluate to reduce the current peak by increasing the value of the inductance. If this is not possible, we can evaluate other possibilities.
First, Ilim is comparing the current cycle-by-cycle peak value, not the average.
If the threshold of Ilim is overcome by the cycle-by-cycle peak for several consecutive cycles it can trigger warning, and eventually an output shut-down.
In ACT88422 Ilim has two thresholds for Buck4, respectively at 2A and 4A. They are selectable by register bit 1 in register A5h.
If also the highest threshold can´t allow a correct startup the only alternative is to disable the Ilim shut-down at least during the start-up, by writing the bit 5 of Register address 0xB1h after voltage on capacitor is ramped up the shut down can be enabled again.
Pay attention, because for the time the Ilim shut-down is disabled, this output is not protected against overcurrents.