VND5E025BK-E Application information
Doc ID 16273 Rev 8 23/34
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).
3.1.2 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 (≈600mV) in the input
threshold and in the status output values if the microprocessor ground is not common to the
device ground. This shift will not vary if more than one HSD shares the same diode/resistor
network.
3.2 Load dump protection
D
ld
is necessary (voltage transient suppressor) if the load dump peak voltage exceeds the
V
CC
max DC rating. The same applies if the device is subject to transients on the V
CC
line
that are greater than the ones shown in the ISO 7637-2: 2004(E) table.
3.3 MCU I/Os protection
If a ground protection network is used and negative transient are present on the V
CC
line,
the control pins will be pulled negative. ST suggests to insert a resistor (R
prot
) in line to
prevent the MCU I/Os pins to latch-up.
The value of these resistors is a compromise between the leakage current of MCU and the
current required by the HSD I/Os (Input levels compatibility) with the latch-up limit of MCU
I/Os:
-V
CCpeak
/I
latchup
≤ R
prot
≤ (V
OHμC
-V
IH
-V
GND
) / I
IHmax
Calculation example:
For V
CCpeak
= - 100 V and I
latchup
≥ 20 mA; V
OHµC
≥ 4.5 V
5kΩ ≤ R
prot
≤ 180 kΩ
Recommended values: R
prot
=10 kΩ, C
EXT
=10 nF.
