ZHCS984B June 2012 – May 2019 TPS54678
PRODUCTION DATA.
The TPS54678 allows monotonic start-up into prebiased output. The low-side FET turns on for a short time period every cycle before the output voltage reaches the prebiased voltage. This ensures the boot cap has enough charge to turn on the top FET when the output voltage reaches the prebiased voltage.
The TPS54678 also implements low-side current protection by detecting the voltage over the low-side MOSFET. When the converter sinks current through the low side FET and if the current exceeds 4 A, the control circuit turns the low-side FET off. Due to the implemented prebias function, the low-side FET reverse current protection should not be reached, but it provides another layer of protection.