L9663 datasheet(42/106 Pages) STMICROELECTRONICS

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Diagnosis

L9663

42/106

DS11401 Rev 6

Diagnosis

The PSIx output voltage is monitored to detect and protect against failures:



Under voltage on PSI5x outputs



Short to ground (STG)



Leakage to ground (LTG)



Open load (OL)



Short to battery (STB)



Short between channels (through cross coupling test) and to protect the transceiver IC

in case of negative voltages or excessive voltage on the PSIx outputs.

This module consists of the following sub modules:



PSIx output voltage clamping circuit



PSIx short circuit detection and current limitation



PSIx reverse voltage monitoring



PSIx under voltage monitoring



VAS under voltage monitoring



Sync pulse voltage monitoring

4.1

PSIx output voltage clamping circuit

The clamping circuit allows control of the maximum voltage level on the PSIx output, despite

a possible over voltage fault on the VAS line.

The Transceivers clamp the PSIx voltage to less than 11 V in data transmission or less than

16.5 V in sync pulse with a 50 mA typical sink current.

4.2

PSIx output under voltage monitoring

The under voltage monitoring detects a low voltage level of the sensor supply line PSIx.

Basic features:



Under voltage monitoring with filter time

Figure 22. Timing for PSIx under voltage detection

PSIx

PSIx undervoltage

threshold

undervoltage shorter

than filtertime

undervoltage longer

than filtertime

PSIx undervoltage

flag

GAPG2010151143PS

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