ZHCSCB9D April 2014 – December 2019 TPS22965-Q1
When the switch is enabled, the output capacitors must be charged up from 0-V to the set value (3.3 V in this example). This charge arrives in the form of inrush current. Inrush current can be calculated using Equation 3.
The TPS22965x-Q1 offers adjustable rise time for VOUT. This feature allows the user to control the inrush current during turn-on. The appropriate rise time can be calculated using the design requirements and the inrush current equation. See Equation 4 and Equation 5.
To ensure an inrush current of less than 400 mA, choose a CT value that yields a rise time of more than 181.5µs. See the oscilloscope captures in the Application Curves section for an example of how the CT capacitor can be used to reduce inrush current.