VN5160STR-E datasheet(21/31 Pages) STMICROELECTRONICS

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VN5160S-E

Application Information

Doc ID 13493 Rev 5

21/31

3.1.2

Solution 2: a diode (DGND) in the ground line

A resistor (RGND=1kshould be inserted in parallel to DGND 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 will produce 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 will not vary if more than one HSD shares the same diode/resistor

network.

3.2

Load dump protection

Dld is necessary (Voltage Transient Suppressor) if the load dump peak voltage exceeds the

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 7637-2: 2004(E) table.

3.3

MCU I/Os protection

If a ground protection network is used and negative transient 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  (VOHC-VIH-VGND) / IIHmax

Calculation example:

For VCCpeak= - 100V and Ilatchup  20mA; VOHµC  4.5V

  R

prot  180k.

Recommended Rprot values is 10k

3.4

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 external resistor has to be selected according to the following requirements:

no false open load indication when load is connected: in this case we have to avoid

VOUT to be higher than VOlmin; this results in the following condition

VOUT= (VPU/(RL+RPU))RL<VOlmin.

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.

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