8.3.2.2 Overvoltage Clamp (OVC)

The TPS25952x, TPS25953x, TPS25954x devices provide a mechanism to clamp the output voltage to a predefined level quickly if the input voltage crosses a certain threshold. This ensures the load is not exposed to high voltages on any overvoltage at the input supply, and lowers the dependency on external protection devices (such as TVS/Zener diodes) in this condition. Once the input supply voltage rises above the OVC threshold voltage V_OVC, the device responds by clamping the voltage to V_CLAMP within a very short response time t_OVC. As long as an overvoltage condition is present on the input, the output voltage will be clamped to V_CLAMP. When the input drops below the output clamp threshold V_OVC, the clamp releases the output voltage. See Figure 49.

During the overvoltage clamp condition, there could be significant heat dissipation in the internal FET depending on the V_IN - V_OUT voltage drop and the current through the FET leading to a thermal shutdown if the condition persists for an extended period of time. In this case, the device would either stay latched-off or start a auto retry cycle as explained in the Overtemperature Protection (OTP) section.

Figure 49. TPS2595xx Overvoltage Clamp Response (Auto-Retry)

Multiple device options are offered with different clamping voltage thresholds. See the Device Comparison Table for list of available voltage clamp options.