VND9012AJ datasheet(28/46 Pages) STMICROELECTRONICS

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Figure 34. M0-9 application schematic

VDD

OUT

ADC in

OUT

GND

Logic

OUTPUT

GND

FaultRST

INPUT

SEn

SEL

VCC

Current mirror

Rprot_SEn

Rprot

+5V

GND

Rsense

GND

Cext

GND

1 μF

Rload_nom

4.3

MCU I/Os 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 both to prevent the microcontroller I/O pins from

latching-up and to protect the HSD inputs.

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.

Equation

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

Calculation example:

For VCCpeak = -150 V; Ilatchup ≥ 20 mA; VOHµC ≥ 4.5 V

7.5 kΩ ≤ Rprot ≤ 140 kΩ.

Recommended values: Rprot = 15 kΩ

A different value of the resistor has to be used for SEn pin, Rprot_SEn, as reported in Figure 32. Application

diagram.

4.4

CS - analog current sense

Diagnostic information on device and load status are provided by an analog output pin (CS) delivering the

following signals:

•

Current monitor: current mirror of channel output current

Those signals are routed through an analog multiplexer which is configured and controlled by means of SELx and

SEn pins, according to the address map in Table 7.

VND9012AJ

Application information

DS12727 - Rev 5

page 28/46

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