L9680 datasheet(175/286 Pages) STMICROELECTRONICS

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DS11615 Rev 7

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L9680

Deployment drivers

285

Figure 36. Deployment timer diagnostic sequence

Squib/pyroswitch diagnostics with common SRx connected loops

In case of two SRx pins are intentionally connected together, the PD_CURR_CSR bit of the

Deployment Configuration register (DCR_x, where x = 0, 2, 4, 6, 8, A) must be used to

indicate which loop pairs have the common SRx connection. The purpose of this additional

bit is to control the pull-down current on each channel to be consistent with or without the

Common SRx connected loops. When the DCR_x(PD_CURR_CSR) bit is set for one loop

pair and the Deployment diagnostic is run on that loop pair, the pull-down current is disabled

on both channels of the loop pair selected.

For the squib/pyroswitch channel pair with common SRx connection, to understand if the

two SFx pins are shorted together, the squib/pyroswitch resistance measurement must be

required with the following setting: LPDIAGREQ[12:11]=11. In this way the ISRC current

generator is enabled on the channel selected by RES_MEAS_CHSEL[3:0] bits while the

Differential Operational Amplifier is connected on the other channel of the squib/pyroswitch

channel pair. If the short between the two SFx pin is not present then the Squib/pyroswitch

resistance measurement results will be close to 0, otherwise it will be half the real

squib/pyroswitch resistance.

Loop diagnostics control and results registers

Diagnostic tests and channels for each test are controlled through the Loop Diagnostic

Request Register (LPDIAGREQ), diagnostic results are stored in the Loop Diagnostic

Status Register (LPDIAGSTAT).

GAPGPS02282

PT_WAIT

PT2

PT3

PT4

PT12

PT_OFF

PT5

PT6

PT7

PT8

PT9

PT10

PT11

PT1

PULSE_TEST1=1 for Tpulse_high

PULSE_TESTother=0

PT_TMR=0

PT_TMR=Tpulse_period/

PULSE_TEST2=1 for Tpulse_high

PULSE_TESTother=0

PT_TMR=0

PT_TMR=Tpulse_period/

PULSE_TEST3=1 for Tpulse_high

PULSE_TESTother=0

PT_TMR=0

PT_TMR=Tpulse_period/

PULSE_TEST4=1 for Tpulse_high

PULSE_TESTother=0

PT_TMR=0

PT_TMR=Tpulse_period/

PULSE_TEST5=1 for Tpulse_high

PULSE_TESTother=0

PT_TMR=0

PT_TMR=Tpulse_period/

PULSE_TESTn=1 for Tpulse_high

PULSE_TESTother=0

PT_TMR=0

PT_TMR=Tpulse_period/

PULSE_TEST12=1 for Tpulse_high

PULSE_TESTother=0

PT_TMR=0

PT_TMR=Tpulse_period/

PULSE_TEST all_chx=0

PT_TMR=Tpulse_period/

PULSE_TESTx=0

DIAG state & SPI_SYSREQ(DSTEST=PULSE) /

From any state:

PULSE_TESTx=0

SSM_RESET /

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