VND810MSP datasheet(9/19 Pages) STMICROELECTRONICS

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VND810MSP

LOAD DUMP PROTECTION

Dld is necessary (Voltage Transient Suppressor) if the

load dump peak voltage exceeds VCC max DC rating. The

same applies if the device will be subject to transients on

the VCC 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 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

µC I/Os.

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

Calculation example:

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

Ω ≤ R

prot ≤ 65kΩ.

Recommended Rprot value is 10kΩ.

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:

1) 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.

2) 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.

The values of VOLmin, VOLmax and IL(off2) are available in

the Electrical Characteristics section.

VOL

V batt.

VPU

RPU

DRIVER

LOGIC

INPUT

STATUS

VCC

OUT

GROUND

IL(off2)

Open Load detection in off state

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