SLUU182A January 2004 – March 2022 TPS5124
The TPS5124 includes fault latch function with a user-adjustable timer to latch the MOSFET drivers in case of a fault condition. When either the OVP or UVP comparator detects a fault condition, the timer starts to charge C18, the external capacitor connected to the SCP pin. The circuit is designed so that for any value of C18, the undervoltage latch time, tUVPL, is about five times larger than the overvoltage latch time tOVPL. The equations needed to calculate the required value of C18 for the desired overvoltage and undervoltage latch delay times are calculated in Equation 17 and Equation 18.
where
For the EVM, tUVPL = 7 ms and tOVPL = 1.5 ms, so C18 = 0.01 μF.
If the voltage on the SCP pin reaches 1.185 V, the fault latch is set, and the MOSFET drivers are set as follows.