L9658 datasheet(25/64 Pages) STMICROELECTRONICS

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L9658

Functional description

Doc ID 14219 Rev 3

25/64

During the deployment, L9658 turn on the respective high (SQH) and low side (SQL) drivers

for tDEPLOY. Once deployment is initiated it can not be terminated. When a channel is in

deployment, this particular channel shall only act upon certain SPI messages. These SPI

messages and their responses are summarized in below table. The rest of the channels

shall resume their operations and respond to specific SPI commands.

During a deployment, the device ignores arming commands. and does not refresh or

terminate the pulse stretch timer when it receives an arming command.

4.10

DEPEN

DEPEN is a deployment enable input, which is an active high input. When this pin is

asserted, L9658 is able to turn on its high and low side drivers upon receiving a valid

deployment command or a MOS diagnostic request. DEPEN can not interrupt a deployment

that is already in-progress.

When DEPEN is negated, it inhibits the low side and the high side MOS from turning on

(inhibit the deployment). When a MOS diagnostic is requested, the device executes the

diagnostic even without the ability to turn on the MOS. It set the proper SPI threshold bits.

SPI remains functional while this pin is pulled low.

When DEPEN is negated, SPI deploy command is prevented from initiating the pulse stretch

timer. Regardless of DEPEN, SPI deploy command status bits reports the state of SPI

deploy command bits sent in the previous SPI transfer. This feature is required so that the

processor can diagnose SPI deploy command bits with DEPEN negated.

Regardless of DEPEN, arming signal is able to initiate the pulse stretch timer. This feature

will be used for the processor to diagnose the arming signal.

When the pulse stretch timer has been running, changes in the state of DEPEN does not

affect the pulse stretch timer. The pulse stretch timer is not affected regardless of the pulse

stretch timer being started by an arming signal or a SPI deploy command.

A de-glitch timer is provided to DEPEN pin. The timer protects this pin against spurious

glitches. The device neglects DEPEN signal if it is asserted/negated for shorter than

tGLITCH.

Table 12.

SPI transmission during a deployment

SPI MOSI

SPI MISO(1)

SPI MISO sent in the next SPI transmission.

Notes

SPI fault response

MOSI register mode message shall be ignored

Command mode

Execute for channels not in deployment; no effect

to deploying channel

Diagnostic mode

SPI fault response

MOSI diagnostic mode message shall be ignored

Monitor mode

Status response

Execute for all channels

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