Tool/software:
I have a design that uses the UCC14130-Q1 part in the single output configuration to generate an 18V nominal output from a 15V regulated input (configured like figure 12-2 of the datasheet). My design has 20uF of capacitance on the VIN pins and 10.1 uF of capacitance on the VDD pins. Unfortunately, when the device is enabled the change in current is causing the voltage regulator upstream to enter a safety shutdown state. Due to some system level constraints, I need to fix this behavior by changing this circuit and cannot adjust the upstream regulator. I have been able to avoid the shutdown state by dropping the output capacitance in this circuit. At values of 2.0 uF and below the device boots up consistently and performs as expected.
In looking at section 12.2.2.1 of the datasheet (capacitor selection) table 12-2 calls out a value greater than 2.2 uF for Cout to reduce the output voltage ripple. Other than that I am not seeing any minimum output capacitance required for stability. Is there an absolute minimum output capacitance required to ensure proper operation of the device or is it based solely on the amount of ripple allowed.
