L9965P datasheet(31/104 Pages) STMICROELECTRONICS

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3.6.1.3

Programmable delay

In systems where multiple L9965P ICs are used, it may be required to apply a phase shift between pyro-fuses

deployment (see example in the Figure 15).

In such case, the deploy control stage can be configured to apply a tDEPLOY_DELAY shift to the start of the

deployment procedure (when both arming conditions are set).

The delay is programmed through the FENx_DLY_CFG bit.

The delay insertion is only available in case of deployment triggered via FENH/FENL signals, while it shall be

managed by MCU timers in case of deployment triggered via SPI.

Figure 15. Example of two pyro-drivers in a system

L9965P

RPYRO

PACK+

PACK-

L9965C

RSHUNT

FENH

FENL

FENH

FENL

FAUL

0us delay

500us delay

3.6.1.4

Pyro-fuse trigger via SPI

The output switches can be triggered also by SPI commands:

•

Writing the 0x155 command in the HS_CMD register

•

Writing the 0x2AA command in the LS_CMD register

HS_CMD and LS_CMD are located at different addresses of the SPI register map so that a sequence of two

commands is needed to perform a deployment. The two commands are intentionally different to prevent

inadvertent deployment.

L9965P

Functional description

DS14702 - Rev 4

page 31/104

L9965P Datasheet(PDF) 31 Page - STMicroelectronics