The TMUX7436F detects overvoltage inputs by comparing the voltage on a source pin (Sx) with the supplies (V_DD and V_SS). A signal is considered overvoltage if it exceeds the supply voltages by the threshold voltage (V_T).

The switch automatically turns OFF regardless of the logic controls when an overvoltage is detected. The source pin becomes high impedance and ensures only small leakage current flows through the switch. The drain pin (Dx) behavior can be adjusted by controlling the drain response (DR) pin in the following ways:

1. DR pin floating or driven above V_IH:

   If the DR pin is driven above VIH level of the pin, then the drain pin becomes high impedance (Hi-Z) upon overvoltage fault.

2. DR driven below V_IL:

   If the DR pin is driven below VIL level of the pin, and the channel expeirencing the overvoltage fault condition is currently being selected by the logic controls (EN, SELx), then the drain pin (Dx) is pulled to the supply that was exceeded through a 40 kΩ resistor. For example, if the source voltage exceeds V_DD, then the drain output is pulled to V_DD. If the source voltage exceeds V_SS, then the drain output is pulled to V_SS. The pull-up/pull-down impedance is approximately 40 kΩ, and as a result, the drain current is limited during a shorted load (to GND) condition.

Figure 8-1 shows a detailed view of the how the DR pin, SELx pin, and EN pin controls the output state of the drain pin under a fault scenario.