L9680 datasheet(194/277 Pages) STMICROELECTRONICS

194 / 277 page

DC sensor interface

L9680

194/277

DocID029257 Rev 1

Each output is protected against



Overload conditions by current limit



Ground offset between the ECU and the loads of up to ±1 V.



Loss of ECU battery



Loss of ground



Unpowered shorts to battery



Shorts to ground

11.1

Passenger inhibit interface

L9680 provides a feature to deactivate passenger restraint devices based on a

preprogrammed mask. It generates a signal (PSINHINT) based on microcontroller-initiated

measurements performed on DC Sensor channel 0. The PSINHINT signal is bitwise AND-

ed with the LOOP_MATRIX_PSINH mask register, allowing selective deactivation of squib

loops independent of microcontroller control. This signal is also inverted and output on the

PSINHB pin of the IC to activate externally controlled squib loops.

Figure 49. Passenger inhibit logic diagram

An upper and lower threshold is preprogrammed via SPI by writing the desired 10-bits

values into the PADTHRESH_HI and PADTHRESH_LO registers during the Diag state.

These thresholds define the measurement window where the passenger restraints are

active. Any measurement outside this window will result in the assertion of the PSINHINT

signal (as described below), thereby deactivating the squib loops identified in the PSINH

mask. The PSINH mask is also preprogrammed during the Diag state.

L9680 Datasheet(PDF) 194 Page - STMicroelectronics