Application information VND830MSP-E
18/28 Doc ID 10903 Rev 4
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 Section 3.1.2).
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 produces a shift (∼600 mV) in the input threshold
and in the status output values if the microprocessor ground is not common to the device
ground. This shift does 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 Table 13.
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 are pulled negative. ST suggests to insert a resistor (R
prot
) in line to prevent
the microcontroller I/Os pins to latch-up.
The value of these resistors is a compromise between the leakage current of microcontroller
and the current required by the HSD I/Os (Input levels compatibility) with the latch-up limit of
microcontroller I/Os.
-V
CCpeak
/I
latchup
≤ R
prot
≤ (V
OH
µ
C
-V
IH
-V
GND
) / I
IHmax
Calculation example:
For V
CCpeak
= -100 V and I
latchup
≥ 20 mA; V
OH
µ
C
≥ 4.5 V
5kΩ ≤ R
prot
≤ 65 kΩ.
Recommended values:
R
prot
=10 kΩ.
3.4 Open-load detection in off-state
Off-state open-load detection requires an external pull-up resistor (R
PU
) connected between
OUTPUT pin and a positive supply voltage (V
PU
) like the +5 V line used to supply the
microprocessor.
The external resistor has to be selected according to the following requirements:
