SLVSAF1E October 2010 – May 2019 TPS54388-Q1
The VIN pin voltage on the VIN pin falling below 2.6 V disables the TPS54388-Q1 device. If an application requires a higher undervoltage lockout (UVLO), use the EN pin as shown in Figure 22 to adjust the input voltage UVLO by using two external resistors. TI recommends using the EN resistors to set the UVLO falling threshold (V(STOP)) above 2.6 V. Set the rising threshold (V(START)) to provide enough hysteresis to allow for any input supply variations. The EN pin has an internal pullup current source that provides the default condition of TPS54388-Q1 operation when the EN pin floats. Once the EN pin voltage exceeds 1.25 V, the circuitry adds an additional 1.6 μA of hysteresis. Pulling the EN pin below 1.18 V removes the 1.6 μA. This additional current facilitates input voltage hysteresis.