VN920D-B5_04 Datasheet, PDF (8/22 Pages) STMicroelectronics – HIGH SIDE DRIVER

VN920D-B5 / VN920DSO
APPLICATION SCHEMATIC
+5V
+5V
R_prot
STATUS
µC
R_prot
INPUT
V_CC
D_ld
GND
OUTPUT
V_GND
R_GND
D_GND
GND PROTECTION NETWORK AGAINST
REVERSE BATTERY
Solution 1: Resistor in the ground line (R_GND only). This
can be used with any type of load.
The following is an indication on how to dimension the
R_GND resistor.
1) R_GND ≤ 600mV / (I_S(on)max).
2) R_GND ≥ (−V_CC) / (-I_GND)
where -I_GND is the DC reverse ground pin current and can
be found in the absolute maximum rating section of the
device’s datasheet.
Power Dissipation in R_GND (when V_CC<0: during reverse
battery situations) is:
P_D= (-V_CC)²/R_GND
This resistor can be shared amongst several different
HSD. Please note that the value of this resistor should be
calculated with formula (1) where I_S(on)max becomes the
sum of the maximum on-state currents of the different
devices.
Please note that if the microprocessor ground is not
common with the device ground then the R_GND will
produce a shift (I_S(on)max * R_GND) in the input thresholds
and the status output values. This shift will vary
depending on 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
the ST suggests to utilize Solution 2 (see below).
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 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.
Series resistor in INPUT and STATUS lines are also
required to prevent that, during battery voltage transient,
the current exceeds the Absolute Maximum Rating.
Safest configuration for unused INPUT and STATUS pin
is to leave them unconnected.
LOAD DUMP PROTECTION
D_ld is necessary (Voltage Transient Suppressor) if the
load dump peak voltage exceeds V_CC 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
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 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.
-V_CCpeak/I_latchup ≤ R_prot ≤ (V_OHµC-V_IH-V_GND) / I_IHmax
Calculation example:
For V_CCpeak= - 100V and I_latchup ≥ 20mA; V_OHµC ≥ 4.5V
5kΩ ≤ R_prot ≤ 65kΩ.
Recommended R_prot value is 10kΩ.
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