ZHCSB15B May 2013 – October 2023 TPS54531
PRODUCTION DATA
Programming the slow-start time externally is highly recommended because no slow-start time is implemented internally. The TPS54531 device effectively uses the lower voltage of the internal voltage reference or the SS pin voltage as the reference voltage of the power supply that is fed into the error amplifier and regulates the output accordingly. A capacitor (CSS) on the SS pin to ground implements a slow-start time. The TPS54531 device has an internal pullup current source of 2 μA that charges the external slow-start capacitor. Use Equation 3 to calculate the slow-start time (10% to 90%).
where
The slow-start time must be set between 1 ms to 10 ms to ensure good startup behavior. The value slow-start capacitor must not exceed 27 nF.
During normal operation, the TPS54531 device stops switching if the input voltage drops below the VIN UVLO threshold, the EN pin is pulled below 1.25 V, or a thermal shutdown event occurs.