L9678P datasheet(139/203 Pages) STMICROELECTRONICS

No. de pieza	L9678P

Descripción Electrónicos	Automotive user configurable airbag IC

PDF	203 Pages

Scroll/Zoom	100%

Fabricante Electrónico	STMICROELECTRONICS [STMicroelectronics]

Página de inicio	http://www.st.com

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139 / 203 page

DocID029274 Rev 3

139/203

L9678P, L9678P-S

Safing logic

202

Safing logic

10.1

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 4 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 to 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 39. Top level safing engine flow chart

L9678P Datasheet(PDF) 139 Page - STMicroelectronics