VNQ830M
Solution 2: A diode (DGND) in the ground line.
A resistor (RGND=1kΩ) should be inserted in parallel to
DGND 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.
LOAD DUMP PROTECTION
Dld is necessary (Voltage Transient Suppressor) if the
load dump peak voltage exceeds VCC max DC rating. The
same applies if the device will be subject to transients on
the VCC line that are greater than the ones shown in the
ISO T/R 7637/1 table.
µC I/Os PROTECTION:
If a ground protection network is used and negative
transients are present on the VCC line, the control pins will
be pulled negative. ST suggests to insert a resistor (Rprot)
in line to prevent the µC I/Os pins to latch-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.
-VCCpeak/Ilatchup ≤ Rprot ≤ (VOHµC-VIH-VGND) / IIHmax
Calculation example:
For VCCpeak= - 100V and Ilatchup ≥ 20mA; VOHµC ≥ 4.5V
5kΩ ≤ Rprot ≤ 65kΩ.
Recommended Rprot value is 10kΩ.
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