9

Reverse polarity on VDD

The reverse polarity on VDD can be implemented on board by placing a diode between the GNDDD pin and GND

digital ground.

The diode must be chosen by taking into account VRRM>|VDD| and its power dissipation capability:

PD≥IDD×VF

(4)

Note:

In normal operation (no reverse polarity), there is a voltage drop (ΔV = VF@(Idd)) between GNDDD of the device

and digital ground of the system. In order to guarantee to proper

triggering of the input signal, ΔV(max.) must result lower than VIH(MIN).

Figure 24. VDD reverse polarity protection

Note:

Input(i) is intended as any input pin on logic side.

ISO808A, ISO808A-1

Reverse

polarity on VDD

DS14170 - Rev 1

page 24/38