VN5E050AJ-E Application information
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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 requires the use of a large resistor, or several devices
have to share the same resistor, then ST suggests using solution 2 below.
3.1.2 Solution 2: diode (D
GND
) in the ground line
Note that a resistor (R
GND
=1kΩ) 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 (j600mV) 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/O protection
If a ground protection network is used and negative transients 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 µC I/O pins from latching up.
The value of these resistors is a compromise between the leakage current of µC and the
current required by the HSD I/Os (Input levels compatibility) with the latch-up limit of µC
I/Os:
-V
CCpeak
/I
latchup
≤ R
prot
≤ (V
OH
μ
C
-V
IH
-V
GND
) / I
IHmax
Calculation example:
For V
CCpeak
= - 100V and I
latchup
≥ 20mA; V
OHµC
≥ 4.5V
5kΩ ≤ R
prot
≤ 180kΩ
Recommended values: R
prot
=10kΩ, C
EXT
=10nF.
