L9679E datasheet(70/127 Pages) STMICROELECTRONICS

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6 V ≤ V_SSxy ≤ 16.7 V

with -40°C ≤ Tj_start ≤ 130°C;

6V ≤ V_SSxy ≤ 16V

with -40°C ≤ Tj_start ≤ 150°C;

Squib/Pyroswitch Deploy current profile = 1.75 A / 3.2 ms (DCR_Deploy_Time ≤ 54):

6 V ≤ V_SSxy ≤ 14.7 V

with -40 °C ≤ Tj_start ≤ 130 °C;

6 V ≤ V_SSxy ≤ 13.9 V

with -40 °C ≤ Tj_start ≤ 150 °C;

These requirements are valid considering also the case where all loops are shorted to ground during deployment

(SFx = 0 V or SRx = 0 V).

7.1.2

Deploy command expiration timer

Deploy commands are received for all channels using SPI communications. Once a deploy command is received,

it will remain valid for a specified time period selected in the Deploy Configuration Register (DCRx). The deploy

status and deploy expiration timer can be read through the Deploy Status Register (DSRx). The deploy expiration

timer is selectable via 2 bits and the maximum programmable time is 500 ms nominal.

7.1.3

Deployment control flow

Deployment control logic requires the following conditions to be true to successfully operate a deployment:

•

POR = 0

•

SSM to be in Safing State

•

A valid arming condition by FENx signals to be set

•

Channel-specific deploy command request bits to be set via SPI in the Deploy command Register

(DEPCOM)

•

A global deployment state has to be active, as described in the following figure.

Figure 13. Global SPI deployment enable state diagram

SSM_Reset

UNLOCK

SPI_SPIDEPEN(DEPEN_WR)

DEP_DISABLED

DEP_ENABLED

LOCK

SPI_SPIDEPEN(DEPEN_WR)

GADG0903181136PS

In case a multiple deployment request is needed, i.e. deploying the same channel in sequence, a toggle on

DEP_DISABLED has to be performed and a new DEPCOM command on the same channel has to be sent.

The SPI DEPCOM command is ignored if the device is in the DEP_DISABLED state and the deploy command is

not set. While in DEP_ENABLED state, the following functionalities that could be active are forced to their reset

state:

•

All squib/pyroswitch diagnostic current or voltage sources

•

All squib/pyroswitch and ADC diagnostic MUX settings, state machine, etc.

The SPI_LOCK and SPI_UNLOCK signals are available in the SPIDEPEN command:

The arming valid condition is assessed by using the 3 arming discrete input pins FEN1, FEN2 and FENL. All of

these three pins are active high. The device allows two configurations:

L9679E

Deployment drivers

DS12485 - Rev 8

page 70/127

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