7.3.3 Soft Start and Prebiased Soft Start

The VDDQ buck has an internal 1.6-ms soft start and VPP buck has an internal 1-ms soft start. Provide the voltage supply to PVIN, PVIN_VPP and VCC_5V before asserting SLP_S4 to be high, when the SLP_S4 pin becomes high, the internal soft-start function begins ramping up the reference voltage to the PWM comparator.

If the output capacitor is prebiased at start-up, the devices initiate switching and start ramping up only after the internal reference voltage becomes greater than the feedback voltage. This scheme ensures that the converters ramp up smoothly into regulation point.