NCV8461

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6

REVERSE BATTERY PROTECTION

The NCV8461 provides reverse battery protection up to

32 V. This protection requires a Resistor in the GND path.

The recommended GND resistor is 150

W, but a variety of

resistor values can be chosen for this purpose. The graph

below shows the considerations and constraints for selection

of the GND resistor. Figure 2 shows the power dissipation

in the GND resistor during a 32 V reverse battery event on

the left axis, while the right axis shows the voltage drop

across the GND resistor while in normal operation. The far

right side of the graph is grayed out to indicate that the

voltage drop across the resistor is too high, and the part will

not be able to turn on with a standard 5 V on the input pin.

Selection of the optimal GND resistor requires balancing the

power dissipation considerations while in a reverse battery

event, with the turn on capability of the input signal during

normal operation.

Figure 2. Reverse Battery Considerations

Figure 3. Reverse Battery Protection Circuit