VN610SP

Application information

Doc ID 6236

Rev 5

17/26

If the calculated power dissipation requires the use of a large resistor, or several devices

have to share the same resistor, then ST suggests using solution 2 below.

3.1.2

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. 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.

3.2

Load dump protection

Dld is necessary (voltage transient suppressor) if the load dump peak voltage exceeds the

VCC maximum DC rating. The same applies if the device is subject to transients on the VCC

line that are greater than those shown in the ISO T/R 7637/1 table.

3.3

MCU I/O 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/O pins from latching 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

Example

For the following conditions:

VCCpeak = - 100V

Ilatchup ≥ 20mA

VOHμC ≥ 4.5V

5k

Ω ≤ Rprot ≤ 65kΩ.

Recommended values are:

Rprot = 10kΩ

Obsolete

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- Obsolete

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