L9679P datasheet(190/272 Pages) STMICROELECTRONICS

No de pièce	L9679P

Description	Automotive advanced airbag IC for mid/high end applications

PDF	272 Pages

Scroll/Zoom	100%

Fabricant	STMICROELECTRONICS [STMicroelectronics]

Site Internet	http://www.st.com

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190 / 272 page

Safing logic

L9679P

190/272

DocID029275 Rev 1

Safing logic

12.1

Safing logic overview

The integrated safing logic uses data from on-board and remote locations by decoding the

various SPI communications between the interfaces and the main microcontroller. The

safing logic has several programmable features enabling its ability to decode SPI

transmissions and can process data from up to 16 sensors. The operating mode involves

simple symmetrical data threshold comparisons, with the use of symmetrical or

asymmetrical counters. A high level diagram is shown in the figure below. Please note that

this top-level diagram is simplified, and references more detailed flowcharts to show a)

message decoding, b) valid data limits, c) effects of the 'combine' function, d) comparison to

thresholds and arming, and e) the setting of the 'compare complete bit. Two independent

arming outputs, ARM1INT and ARM2INT, are also mapped internally to any of the

integrated squib drivers.

Figure 49. Top level safing engine flow chart

L9679P Fiches technique(PDF) 190 Page - STMicroelectronics