L9660 datasheet(24/49 Pages) STMICROELECTRONICS

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Functional description

L9660

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cleared. Otherwise, the state of these flags is not affected. The Success flag must be

cleared to allow re-activation of the drivers.

During driver activation the respective high side (SQHx) and low side (SQLx) drivers turn on

for tDEPLOY.

L9660 driver activation does not occur or, if firing is in process, is terminated under the

following conditions:



Power On Reset (POR)



IREF resistance is larger than RIREF_H or smaller than RIREF_L



Loss of ground condition on GND pin

The following conditions are ignored when driver activation is in progress:



RESETB



Valid soft reset sequences



SPI commands except as noted below. Response for ignored commands is 0xD009



FEN function

The following table shows the response when sending SPI commands during deployment.

Note 1: SPI MISO sent in the next SPI transmission.

The L9660 can only deploy a channel when the FEN function is active. Once the drivers are

active the L9660 keeps the drivers on for the required duration regardless of the FEN state.

Once complete a status bit is set to indicate firing is complete.

3.4.2

Firing current measurement

All channels have a 7 bit current measurement register that is used to measure the amount

of time the current is above IMEAS during firing. The maximum measurement for each

channel is 3.175ms nominal based on a bit weight of 25µs. The current measurement

incrementing once the current has exceeded 95% of the nominal target value. The count

continues to increment from the stored value until either a clear command has been issued

for that channel or all ‘1’s are present in the corresponding channel measurement register. If

all ‘1’s are present for a channel’s measurement register and another firing sequence has

been issued the register remains all ‘1’s. Only if a clear command has been issued that

particular register resets to all ‘0’s. All other channels shall keep the stored measurement

count. During firing the current measurement register cannot be cleared. After a clear

command has been issued for a channel then the channel is ready to count if the current

exceeds the specified level. After a POR or software reset the L9660 resets all 4

measurement registers to all ‘0’s.

Table 10. SPI MOSI/MISO response

SPI MOSI

SPI MISO

Response

Configuration

Commands

SPI fault response

MOSI register mode messages are ignored

Deployment Commands Command mode

Execute for channels not in deployment; no effect

to deploying channel

Diagnostic Commands

SPI fault response

MOSI diagnostic mode messages are ignored

Monitor Commands

Status response

Execute for all channels

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