When the external MOSFETs turn OFF during the conditions such as INP control, overvoltage cutoff, overcurrent protection causing an interruption of the current flow, the input parasitic line inductance generates a positive voltage spike on the input and output parasitic inductance generates a negative voltage spike on the output. The peak amplitude of voltage spikes (transients) depends on the value of inductance in series to the input or output of the device. These transients can exceed the Absolute Maximum Ratings of the device if steps are not taken to address the issue. Typical methods for addressing transients include:

• Use of a TVS diode and input capacitor filter combination across input to and GND to absorb the energy and dampen the positive transients.
• Use of a diode or a TVS diode across the output and GND to absorb negative spikes.

The TPS4811-Q1 gets powered from the VS pin. Voltage at this pin must be maintained above V_{(VS_PORR)} level to ensure proper operation. If the input power supply source is noisy with transients, then TI recommends to place a R_VS - C_VS filter between the input supply line and VS pin to filter out the supply noise. TI recommends R_VS value around 100 Ω.

In case where large di/dt is involved, the system and layout parasitic inductances can generate large differential signal voltages between ISCP and CS- pins. This action can trigger false short-circuit protection and nuisance trips in the system. To overcome such scenario, TI recommends to add filter capacitor of 1 nF (C_SCP) across ISCP and CS- pins close to the device. Because nuisance trips are dependent on the system and layout parasitics, TI recommends to test the design in a real system and tweaked as necessary.

The following figure shows the circuit implementation with optional protection components.

Figure 9-18 Circuit Implementation With Optional Protection Components for TPS4811-Q1