L9965P datasheet(39/104 Pages) STMICROELECTRONICS

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Symbol

Parameter

Test condition

Min

Typ Max

Unit

tHS_RET_11

HS delay between

retry attempts

HS_RET_DLY_CFG = 11

1.84

2.16

PR,

PGND

tRET_ROUTINE_DLY

Delay between two

consecutive retry

routines

0.46

0.5 0.54

PR,

PGND

IACT_PD_PR

PR active pull-down

current

0.7

1.3

3.7

Diagnostic routine

The IC integrates an intelligent controller designed to automatically perform diagnostic sweeps aimed at

guaranteeing the ASIL targets on deployment and non-deployment.

Figure 18. Diagnostic routine

ABIST

tABIST

HWSC

tHWSC

VRCM CHECK

tVRCM_CHECK

LEAK TEST

tLEAK_TEST

FET TEST

tFET_TEST

RES MEAS

tFET_CHECK

ER CAP DIAG

tER_CAP_DIAG

The diagnostic flow has been specifically designed to ensure that each step validates the circuitry necessary to

perform subsequent checks.

In case the routine detects a failure during any of the steps, it immediately stops, setting the corresponding fault

flag and asserting the FAULTN line. If there is a fault during ABIST step, the routine does not stop but the

corresponding fault flag is set and the FAULTN line is asserted.

3.7.1

Routine execution modes

Every time the routine is triggered, the FSM moves to the DIAG state.

There are two types of triggers available:

•

On-demand: triggered by MCU

•

Cyclic: autonomously triggered by an internal timer or triggered by an external CWUP pulse

The two execution modes are mutually exclusive: on-demand triggers cannot interrupt cyclic executions and vice-

versa.

3.7.1.1

On-demand

This strategy is available every time the IC is in a NORMAL state.

On-demand execution is triggered by MCU writing DIAG_START = 1 in the DIAG_CMD register and configuring

the steps to be executed in the same command frame:

1. Writing ABIST = 1 enables the ABIST (analog built-in self-test).

2. Writing ADC_HWSC = 1 enables the HWSC (hardware self-check).

3. Writing VRCM_LEAK_TEST = 1 enables the VRCM check and the pyro outputs leakage test.

4. Writing PYRO_RES = 1 enables the pyro igniter resistance measurement.

5. Writing FET_TEST = 1 enables the pyro deployment FETs test. This test includes the VRCM check and the

pyro outputs leakage test.

6. Writing ER_CAP = 1 enables the ER capacitor diagnostic.

During the diagnostic execution the SPI_DIAG_RUNNING bit is set to 1. Once the on-demand diagnostic is

completed, the SPI_DIAG_END bit is set to 1.

On-demand triggers do not increment the internal cycle counter whose value is stored in CYC_DIAG_NCYCLE bit

field in CYCLIC_DIAG_STATUS register.

3.7.1.2

Cyclic

This strategy is available in both full-power mode and low-power mode:

•

When in full power mode (CWUP = 1, static), the periodicity can be configured programming the

tDIAG_ROUTINE_PERIOD_XXX time.

•

When in low power mode (periodic CWUP triggers), the periodicity is given by the CWUP signal.

L9965P

Functional description

DS14702 - Rev 4

page 39/104

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