In case of short circuit and overload current limit, when the device interrupts current flow, input inductance generates a positive voltage spike on the input and output 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:

• Minimizing lead length and inductance into and out of the device
• Using large PCB GND plane
• Using a Schottky diode across the output and GND to absorb negative spikes
• Using low value ceramic capacitor (C_(IN) to approximately 0.1 μF) to absorb the energy and dampen the transients.

The approximate value of input capacitance can be estimated with Equation 10.

Equation 10.

where

• V_(IN) is the nominal supply voltage
• I_(LOAD) is the load current
• L_(IN) equals the effective inductance seen looking into the source
• C_(IN) is the capacitance present at the input

Some applications can require additional Transient Voltage Suppressor (TVS) to prevent transients from exceeding the Absolute Maximum Ratings of the device. These transients can occur during positive and negative surge tests on the supply lines. In such applications, TI recommends to place at least 1 µF of input capacitor.

The circuit implementation with optional protection components (a ceramic capacitor, TVS and Schottky diode) is shown in Figure 10-10

^* Optional components needed for suppression of transients

Figure 10-10 Circuit Implementation With Optional Protection Components for TPS1663x