In the case of a short-circuit and overload current limit when the device interrupts current flow, the input inductance generates a positive voltage spike on the input, and the output inductance generates a negative voltage spike on the output. The peak amplitude of voltage spikes (transients) is dependent on the value of inductance in series to the input or output of the device. Such transients can exceed the absolute maximum ratings of the device if steps are not taken to address the issue. Figure 9-10 illustrates the transient protection circuit. Typical methods for addressing transients include:

• Minimize lead length and inductance into and out of the device.
• Use a large PCB GND plane.
• Connect a Schottky diode (D2) from the OUT pin ground to absorb negative spikes. The OUT pin has an absolute maximum rating of –1 V for negative transient spikes on output.
• Connect a low-ESR capacitor larger than 1 μF at the OUT pin very close to the device.
• Use a low-value ceramic capacitor C_IN = 0.1 μF to absorb the energy and dampen the transients. The approximate value of input capacitance can be estimated with Equation 11.
  Equation 11. $V_{IN-SPIKE}=V_{IN}+\mathrm{ }{I}_{LOAD}\mathrm{ }\times \mathrm{ }\sqrt{\frac{L_{IN}\mathrm{ }}{C_{IN}}}$
• Some applications require additional Transient Voltage Suppressor (TVS) to keep transients below the absolute maximum rating of the device. A TVS can help to absorb the excessive energy dump and prevent it from creating very fast transient voltages on the input of the device. Use a suitable TVS to clamp the transient voltage below the absolute maximum rating of the device.

TVS D1* and Schottky D2* are optional diodes for transient protection on the input and output.

Figure 9-10 Transient Protection with TPS1641x