11/21
VNQ830M-E
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 diffe rent HSD. Also i n this case, the pr esence of
the ground n etwork will produce a shift (
j
600mV) 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 p reven t tha t, d uring batt ery voltag e tr ansie nt,
the current exceeds the Absolute Maximum Rating.
Safest co nfigu ration for unu sed INPU T a nd S TAT US p in
is to leave them unconnected.
LO AD DUMP PROT ECTION
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 V CC 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-V
GND
) / IIHmax
Calculation example:
For VCCpeak= - 100V and Ilatchup ≥ 20mA; VOHµC ≥ 4.5V
5kΩ ≤ Rprot ≤ 65kΩ.
Recommen ded Rpr ot value is 10kΩ.
OPEN LOAD DETECTION IN OFF STATE
Off state open load detection requires an external pull-up
resistor (RPU) connected between OUTPUT pin and a
positive supply voltage (VPU) like the +5V line used to
supply the microprocessor.
The extern al res istor has to be s electe d ac cordin g to t he
following requirements:
1) no fa lse o pen load indic ation whe n lo ad is con necte d:
in this cas e we have to avoid VOUT to be higher th an
VOlmin; this results in the following condition
VOUT=(VPU/(RL+RPU))RL<VOlmin.
2) no misdetection when load is disconnected: in this
case the VOUT has to be higher than VOLmax; this
results in the following condition RPU<(VPU–VOLmax)/
IL(off2).
Because Is(OFF) may significantly increase if Vout is
pulled high (up to several mA), the pull-up resistor RPU
should be connected to a supply that is switched OFF
when the module is in standby.
The values of V OLmin, VOLmax and IL(off2) are ava ilable in
the Electrical Characteristics section.
Figure 9. Open Load detection in off state
VOL
V batt. VPU
RPU
RL
R
DRIVER
+
LOGIC
+
-
INPUT
STATUS
VCC
OUT
GROUND
IL(off2)