Tool/software:
Hello, I'm developing a battery charger based on the PMP41106 application note. Due to the UCC255603 being unavailable for mass production, I'm using the UCC256601. I have the same configuration as the schematic, but it does not charge properly.
When the power is low, the IC is in Burst mode and it charges correctly (pictures 1 and 2), but as soon as the battery voltage increases and the power demand increases, it just charges for a short period and then a fault triggers and it stops switching for 1s (Picture 3). The switching period changes depending on the Vbat and the power demand. During the switching time, it seems to be in Burst mode (Picture 4), even if FBreplica corresponding with the power should be higher than HFBurstEntry.
Should I change something to adapt the circuit to the UCC256601 (apart from the HV pin)?
The Ifb is half of the UCC256603, should I change the LL and set it up to define the Burst threshold differently?
I've checked Isns, BLK, OVP/OTP and I don't see any pin going above the fault threshold, do you know what can be triggering the fault mode?
Picture 1: Low power switching (Pink: SW, Green: Vout, Yellow: Output current) Picture 2: Low power switching (Pink: SW, Green: Vout, Yellow: Output current)
Picture 3: High power swiching (Pink: SW, Green: Vout, Yellow: Output current) Picture 4: High power swiching (Pink: SW, Green: Vout, Yellow: Output current)