8.3.2 Overvoltage Protection (OVP)

The device incorporates circuitry to protect the system during overvoltage conditions. This device features an overvoltage cut off functionality. A voltage more than V_(OVPR) on OVP pin turns off the internal FET and protects the downstream load. To program the OVP threshold, connect a resistor divider from IN supply to OVP terminal to RTN as shown in Figure 21. OVP Overvoltage Cut-off response is shown in Figure 22. OVP pin must not be left floating. If OVP pin could be floating due to dry soldering, an additional zener diode at the output will be required for protection from over voltage.

Figure 21. OVP Threshold Setting

Figure 22. OVP Overvoltage Cut-Off

Programmable overvoltage clamp can also be achieved using LM76202-Q1 by connecting the resistor ladder from Vout to OVP to RTN as shown in Figure 23 . This results in clamping of output voltage close to OVP set-point by resistors R1 and R2. as shown in Figure 24. This scheme will also help in achieving minimal system Iq during off state. For this OVP configurataion, use R1 > 90 kΩ.

Figure 23. Programmable OV Clamp

Figure 24. Programmable Overvoltage Clamp Response

The LM76202-Q1 device also features an internally fixed 38 V overvoltage clamp (V_OVC) functionality. The OVP terminal of theLM76202-Q1 device must be connected to the RTN terminal directly as shown in Figure 25. The LM76202-Q1 clamps the output voltage to V_OVC, when the input voltage exceeds 38 V. During the output voltage clamp operation, the power dissipation in the internal MOSFET is P_D = (V_IN – V_OVC) × I_OUT. Excess power dissipation for prolonged period can make the device to enter into thermal shutdown. Figure 26 illustrates the overvoltage clamp functionality.

Figure 25. Internal Fixed OV Clamp Setting

Figure 26. Internal OV Clamp Response