Datasheet

Electrical specifications VN750PS-E
16/27 Doc ID 16782 Rev 3
Figure 24. Application schematic
2.5 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. R
GND
≤ 600 mV / (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
produces a shift (I
S(on)max
* R
GND
) in the input thresholds and the status output
values. This shift varies 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).
Solution 2: diode (D
GND
) in the ground line A resistor (R
GND
=1 kΩ) should be inserted in
parallel to D
GND
if the device drives an inductive load.
This small signal diode can be safely shared amongst several different HSDs. Also in this
case, the presence of the ground network will produce a shift (≈600 mV) in the input
threshold and in the status output values if the microprocessor ground is not common to the
V
CC
GND
OUTPUT
D
GND
R
GND
D
ld
μ C
+5V
R
prot
V
GND
STATUS
INPUT
+5V
R
prot