Dear TI team,
We are using TPS54260 with LMP8645HV as constant current source to charge a capacitor bank of 100mF with a peak current limit of 3A. Once the capacitor bank is charged, the current requirement of TPS54260 is less than 1A.
Input Voltage : 48V
Output Voltage : 42V
Load : 100mF capacitor Bank (Alluminium Electrolytic 100V rated ) connected through 1 mtr wire. (47uF on PCB)
PCB : 4 Layer (120 cm2)
Heat Sink : >5 cm2 area each on top, ground and bottom layer
With 3A current limit, capacitor bank was charging to 42V in less than 3 seconds. It was working fine for last two months without any problem. But today when its powered ON, it is taking >90 seconds to charge 100mF capacitor and >30 seconds to charge 33mF capacitor. TPS54260 is limiting its current to less than 50mA. But it is maintaining 42V as set by feedback resistor divider.
Is it due to increased on resistance of internal FET or change in internal current limit and abruptly how it can happen? Please help.