9/20
VND830-E
Figure 7. Application Schematic
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
≤ 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 of
the device’s 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
HSD. 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
common with 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 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 the ST suggest to utilize Solution 2 (see
below).
Solution 2:
A diode (D
GND
) in the ground line.
A resistor (R
GND
=1kΩ) should be inserted in parallel to
D
GND
if the device will be driving an inductive load.
This small signal diode can be safely shared amongst
several different HSD. Also in this case, the presence of
the ground network will produce a shift (j600mV) in the
input threshold and the status output values if the
microprocessor ground is not common with the device
ground. This shift will not vary if more than one HSD
shares the same diode/resistor network.
Series resistor in INPUT and STATUS lines are also
required to prevent that, during battery voltage transient,
the current exceeds the Absolute Maximum Rating.
Safest configuration for unused INPUT and STATUS pin
is to leave them unconnected.
LOAD DUMP PROTECTION
D
ld
is necessary (Voltage Transient Suppressor) if the
load dump peak voltage exceeds V
CC
max DC rating.
The same applies if the device will be subject to
transients on the V
CC
line that are greater than the ones
shown in the ISO T/R 7637/1 table.
V
CC
OUTPUT2
D
ld
+5V
R
prot
OUTPUT1
STATUS1
INPUT1
+5V
STATUS2
INPUT2
GND
+5V
µ
C
R
prot
R
prot
R
prot
D
GND
R
GND
V
GND
Obsolete Product(s) - Obsolete Product(s)
