L9779WD-SPI datasheet(96/141 Pages) STMICROELECTRONICS

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Functional description

L9779WD-SPI

96/141

DocID027721 Rev 2

6.14.4

Diagnosis test

After the request of diagnosis by SPI, the diagnosis routine tests the sensor presence or

vacancy and the short circuit to GND or Vbat. When the system is in diagnosis status the

flying wheel interface function doesn't operate. The diagnosis procedure has an operation

time of about min 5ms due to the external transient

The result of diagnosis routine is valid only if the engine is switched off and if the sensor is a

variable reluctance sensor.

In the last operation of the diagnosis protocol writes the diagnosis result in VRSdiag bit and

writes the operative status in VRSstatus bit. If a new request is sent the new value is

overwritten.

Figure 69. Diagnosis test diagram

Table 46. Diagnosis test electrical characteristics

Symbol

Parameter

Test condition

Min

Typ

Max

Unit

VrsP

VrsM

ViThL

Input high-to-low

differential

threshold voltage

--50

VCM

Common mode

operating range

Not to be tested. It is an

application note.

01.653

VclpH

Input high

clamping voltage

|VRS_INP| = |VRS_INM| = 20 mA 3.3 -0.3

3.3 +0.3

VclpL

Input low

clamping voltage

|VRS_INP| = |VRS_INM| = 20 mA

-1.5

-0.3

Vopenload

Output open load

voltage

VRS_INP = VRS_INM Vopenload

Mode R enabled

1.5

(3.3) /2

1.8

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