L9662 datasheet(38/80 Pages) STMICROELECTRONICS

38 / 80 page

Functional description

L9662

38/80

DocID028325 Rev 1

High side safing diagnostics

When the command is received the ASIC will activate IHSS on the selected VRESx. The

diagnostics will measure the difference between VSDIAG and VRESx. The internal

comparator will detect open, short or normal condition based on the differential voltage

between VSDIAG and VRESx.

The results shall be reported in the next SPI message using bits HSS1 and HSS0 as

indicated in the following table. Once the command is issued the voltages shall be captured

on the next falling edge of CS_D.

Voltage measurement diagnostics (VRESx)

When the command is received the ASIC will activate a comparator for the selected

channel. A 2 bit indication of the state of the VRESx pins shall be reported as indicated

below. The results shall be reported in the next SPI message. Once the command is issued

the voltages shall be captured on the next falling edge of CS_D.

Loss of ground

When any of the power grounds (GND0 – 7) are lost, no deployment can occur on the

respective deployment channels because the low side driver will be inactive. The high side

driver for the respective channel can still be activated.

A loss of ground condition on one or several channels will not affect the operation of the

remaining channels. When a loss of ground condition occurs, the source of the low side

MOS will be floating. In this case, no current will flow through the low side driver.

This condition will be detected as a fault by a low side MOS diagnostic. No additional faults

will be reported from any other diagnostic due to this condition.

Table 13. High side safing diagnostics

Condition

Diagnostic Mode HSS Selection

HSS1

HSS0

(VSDIAG-VRESx) < VHSSSHORT_th

VHSSSHORT_th < (VSDIAG-VRESx) < VHSSOPEN_th

VHSSOPEN_th < (VSDIAG-VRESx)

Table 14. Voltage measurement diagnostics

Condition

Diagnostic mode 3

VRESx selection

VR1

VR0

VRESx < VVRESXLO_th

VVRESXLO_th < VRESx < VVRESXHI_th

VVRESXHI_th < VRESx

L9662 Datasheet(PDF) 38 Page - STMicroelectronics

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