VND830MSP

Application information

Doc ID 7379 Rev 5

17/27

Please note that, if the microprocessor ground is not shared by the device ground, then the

RGND produces a shift (IS(on)max * RGND) in the input thresholds and the status output

values. This shift varies depending on how many devices are ON in the case of several high-

side drivers sharing the same RGND .

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 = 1 kΩ) should be inserted in parallel to DGND if the device is 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 produces a shift (

≈600 mV) in the

input threshold and the status output values if the microprocessor ground is not common

with the device ground. This shift not varies 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 are pulled negative. ST suggests to insert a resistor (Rprot) in line to prevent

the microcontroller I/O pins from latching 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:

- VCCpeak / Ilatchup ≤ Rprot ≤ (VOHμC - VIH - VGND) / IIHmax

Example

For the following conditions:

VCCpeak = -100 V

Ilatchup ≥ 20 mA

VOHμC ≥ 4.5 V

5k

Ω ≤ Rprot ≤ 65 kΩ.

Recommended values are:

Rprot = 10 kΩ

Obsolete

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- Obsolete

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