VN920-B5H Datasheet, PDF (17/26 Pages) STMicroelectronics – Single-channel high-side solid state relay

VN920-B5H
Application information
3.1.2
Solution 2: diode (D_GND) in the ground line
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 produces a shift (≈600mV) in the input threshold
and in the status output values if the microprocessor ground is not common to the device
ground. This shift not varies if more than one HSD shares the same diode/resistor network.
Series resistor in INPUT lines is also required to prevent that, during battery voltage
transient, the current exceeds the absolute maximum rating.
Safest configuration for unused INPUT pin is to leave it unconnected, while unused SENSE
pin has to be connected to ground pin.
ct(s) ^3.2
Load dump protection
du D_ld is necessary (voltage transient suppressor) if the load dump peak voltage exceeds the
ro ^{VCC max DC rating. The same applies if the device is subject to transients on the VCC line}
that are greater than the ones shown in the ISO T/R 7637/1 table.
lete ^P _3.3
MCU I/Os protection
bso ^{If a ground protection network is used and negative transient are present on the VCC line,}
the control pins is pulled negative. ST suggests to insert a resistor (R_prot) in line to prevent
O _{the µC I/Os pins to latch-up.}
) ^- _{The value of these resistors is a compromise between the leakage current of μC and the}
t(s ^{current required by the HSD I/Os (Input levels compatibility) with the latch-up limit of μC}
c I/Os.
du ^-VCCpeak^/Ilatchup ^{≤ R}prot ^{≤ (V}OHµC^-VIH^-VGND^{) / I}IHmax
ro _{Calculation example:}
P _{For VCCpeak= - 100V and Ilatchup ≥ 20mA; VOHµC ≥ 4.5V}
lete^{5kΩ ≤ Rprot ≤ 65kΩ.}
Obso ^{Recommended values: Rprot =10kΩ.}
Doc ID 16506 Rev 3
17/26