Datasheet

DocID10964 Rev 7 11/19
VNQ860-E VNQ860SP-E Reverse polarity protection
8 Reverse polarity protection
A solution to protect the IC against a reverse polarity condition is proposed in Figure 9.
This schematic is valid with any type of load connected to the outputs of the IC.
The R
GND
resistor value can be selected according to the following conditions:
Equation 1
R
GND
≤ 600 mV / (I
S
in ON state max.).
Equation 2
R
GND
≥ (-V
CC
) / (-I
GND
)
where -I
GND
is the DC reverse ground pin current and can be found in Table 1: Absolute
maximum ratings.
The power dissipation associated to R
GND
during the reverse polarity condition is:
PD = (-V
CC
)
2
/R
GND
This resistor can be shared by different ICs. In such case, I
S
value, indicated in Equation 1,
is the sum of the maximum ON-state currents of the different devices.
Please note that, if the microprocessor ground and the device ground are separated then
the voltage drop across the R
GND
(given by I
S
in ON state max. * R
GND
) produces a
difference between the generated input level and the IC input signal level. This voltage drop
varies depending on how many devices are ON in the case of several high-side switches
sharing the same R
GND
.
Figure 9. Reverse polarity protection
Status
i
Input
i
GND
Output
i
+ Vcc
R
GND
(Optional)
Load
Status
i
Input
i
GND
Output
i
+ Vcc
R
GND
(Optional)
Load