STGAP1STR datasheet(41/67 Pages) STMICROELECTRONICS

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STGAP1S

Functional description

7.14.5

DESAT comparator check

The purpose of this security check is to verify the functionality of the desaturation

comparator.

To perform this test, the following procedure has to be followed:



Set SD = low



Send StartConfig command



Set DESAT_EN = '1'



Set DESCHK = '1'



Send StopConfig command



Set SD = high



Wait 3 µs



Apply at the inputs a gate turn on pulse longer than 500 ns



Read DESAT flag

–

DESAT = '1' → OK (VDESATcomp > VDESATth)

–

DESAT = '0' → FAIL (VDESATcomp < VDESATth)

During this test GON is first turned on and then turned off as soon the test succeeds. In case

the test should fail, the output remains on as long as the input signal remains high.

At the end of the check the DESAT fault remains set (it is latched), and it has to be cleared.

Figure 19. DESAT comparator check circuitry

Floating

Section

Control

Logic

Floating ground

DESAT

GON

GOFF

CLAMP

GNDISO

VDESATth

IDESAT

Level

Shifter

testcontrol

SDO

SDI

SPI

Cblank

IN+

IN-

Control

Logic

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