VN5025AJ-E
Application information
3
Application information
Figure 26. Application schematic
+5V
V
CC
R
prot
CS_DIS
D
ld
µC
R
prot
R
prot
CURRENT SENSE
GND
R
SENSE
C
ext
V
GND
R
GND
D
GND
INPUT
OUTPUT
3.1
3.1.1
GND protection network against reverse battery
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.
2.
R
GND
≤
600mV / (I
S(on)max
).
R
GND
≥ (−
CC
) / (-I
GND
)
V
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).
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