I'm having trouble getting the LTM4622A to regulate at the right voltage. It's putting out about 2.9V rather than the expected 5V. It's set up in the following way:
Parallel operation
Input: 10V (going to all VIN pins)
Desired output: 5V (both feedback pins tied together, 4.12K resistor to ground)
Desired switching frequency: 2.2 MHz (287K resistor to ground on FREQ pin)
RUN pins tied together to a resistor divider providing half of the input voltage.
TRACK/SS pins tied together with 0.01uF to ground.
PGOOD pins tied together and pulled up to 3.3V with 10k resistor
INTVCC to test point
All VOUT pins tied together with ~260uF output capacitance.
Output resistance of ~7.3K ohms
I have disabled everything downstream of the regulator and have tried floating and pulling down SYNC/MODE. Both burst mode and continuous mode regulate at about the same voltage. Unfortunately, I can't immediately tell what PGOOD is doing because I have it pulled up to 3.3V, which is supplied by the 5V rail. When powered, all other pins measure at the expected voltage except for:
FB: expected=0.6V, measured=0.379V
Additionally, in continuous mode, the switching frequency is about 21.4kHz instead of the expected 2.2MHz.
I'm at a loss for what else to look at here. Any suggestions? Thanks.
