When designing with the TPSM336x5, slow
rise in output voltage due to recovery from dropout and soft start must be
considered as a two separate operating conditions, as shown in Figure 7-11 and Figure 7-12. Soft start is triggered by any of the following conditions:
- Power is applied to the VIN pin of the device, releasing undervoltage lockout.
- EN is used to turn on the device.
- Recovery from shutdown due to overtemperature protection
After soft start is triggered, the power module
takes the following actions:
- The reference used in the power module to regulate the output voltage is slowly
ramped up. The net result is that output voltage,
if previously 0 V, takes tSS to reach
90% of the desired value.
- Operating mode is set to auto mode of operation, activating the diode emulation mode for the low-side MOSFET. This allows start-up without pulling the output low. This is true even when there is a voltage already present at the output during a pre-bias start-up.