JAJSN20 September 2021 TPS25854-Q1 , TPS25855-Q1
PRODUCTION DATA
The input supply must be able to withstand the maximum input current and maintain a stable voltage. The resistance of the input supply rail must be low enough that an input current transient does not cause a high enough drop at the TPS2585x-Q1 supply voltage that it causes a false UVLO fault triggering and system reset. If the TPS2585x-Q1 is connected to the input supply through long wires or PCB traces, special care is required to achieve good performance. An additional bulk capacitance can be required in addition to the ceramic input capacitors. The amount of bulk capacitance is not critical, but a 100-μF electrolytic capacitor is a typical choice.
The input voltage must not be allowed to fall below the output voltage. In this scenario, such as a shorted input test, the output capacitors discharge through the internal parasitic diode found between the VIN and SW pins of the device. During this condition, the current can become uncontrolled, possibly causing damage to the device. If this scenario is considered likely, then a Schottky diode between the input supply and the output must be used.