10

Reverse polarity protection

Reverse polarity protection can be implemented on-board using two different solutions:

1.

Placing a resistor (RGND) between IC GND pin and load GND

2.

Placing a diode between IC GND pin and load GND

If option 1 is selected, the minimum resistance value has to be selected according to the following equation:

RGND ≥ VCC / IGND

where IGND is the DC reverse ground pin current and can be found in Section 3 of this datasheet.

Power dissipated by RGND (when VCC < 0: during reverse polarity situations) is:

PD = (VCC)2 / RGND

If option 2 is selected, the diode has to be chosen by taking into account VRRM >|VCC| and its power dissipation

capability:

PD ≥ IS x VF

Note:

In normal conditions (no reverse polarity), due to the diode, there is a voltage drop between GND of the device

and GND of the system.

Figure 14. Reverse polarity protection

This schematic can be used with any type of load.

VNI2140

Reverse polarity protection

DS5977 - Rev 11

page 17/26