Application information VNQ5027AK-E
20/31 Doc ID 12730 Rev 7
3 Application information
Figure 25. Application schematic
Note: Channel 2, 3, 4 have the same internal circuit as channel 1.
3.1 GND protection network against reverse battery
3.1.1 Solution 1: resistor in the ground line (R
GND
only)
This can be used with any type of load.
The following is an indication on how to dimension the R
GND
resistor.
1. R
GND
≤ 600mV / (I
S(on)max
).
2. R
GND
≥ (−V
CC
) / (-I
GND
)
where -I
GND
is the DC reverse ground pin current and can be found in the absolute
maximum rating section of the device datasheet.
Power Dissipation in R
GND
(when V
CC
<0: during reverse battery situations) is:
P
D
= (-V
CC
)
2
/R
GND
This resistor can be shared amongst several different HSDs. Please note that the value of
this resistor should be calculated with formula (1) where I
S(on)max
becomes the sum of the
maximum on-state currents of the different devices.
Please note that if the microprocessor ground is not shared by the device ground then the
R
GND
will produce a shift (I
S(on)max
* R
GND
) in the input thresholds and the status output
values. This shift will vary depending on how many devices are ON in the case of several
high side drivers sharing the same R
GND
.
If the calculated power dissipation leads to a large resistor or several devices have to share
the same resistor then ST suggests to utilize Solution 2 (see below).
V
CC
GND
OUTPUT
D
GND
R
GND
D
ld
μ
C
+5V
V
GND
CS_DIS
IINPUT
R
prot
R
prot
CURRENT SENSE
R
prot
R
SENSE
C
ext
