L9680 datasheet(209/277 Pages) STMICROELECTRONICS

Part #	L9680

Description	Automotive advanced airbag IC for mid/high end applications

PDF	277 Pages

Scroll/Zoom	100%

Manufacturer	STMICROELECTRONICS [STMicroelectronics]

Direct Link	http://www.st.com

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209 / 277 page

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L9680

Safing logic

276

Figure 61. ARMx input/output control logic

12.5.1

Arming pulse stretch

Upon a valid command processed by the safing logic, the Dwell bit to stretch the arming

time assertion (dwell time) applies to each safing record and is used to help safe the

deployment sequence to avoid undesired behaviour.

Once dwell time has started, it will continue, regardless of the En (Record Enable) bit. Dwell

will be truncated in case of SSM reset. Dwell values in the safing records are transferred to

the ARMx signals. A dedicated counter is designed for each ARMx output pin. If different

dwell values are assigned to the same ARMx, the longer value is used. Dwell times can only

be extended, not reduced. If the remaining dwell time is less than the new dwell extension

setting, the new setting will be loaded into the dwell counter.

Dwell times are user programmable.

The behaviour of the pulse stretch timer is shown below.

L9680 Datasheet(PDF) 209 Page - STMicroelectronics