L9679P datasheet(161/279 Pages) STMICROELECTRONICS

161 / 279 page

DS11627 Rev 7

161/279

L9679P

Deployment drivers

278

8.5

Diagnostics

The L9679P provides the following diagnostic feedback for all deployment channels:



High voltage leakage test for oxide isolation check on SFx and SRx



Leakage to battery and ground on both SFx and SRx pins with or without a

squib/pyroswitch



Short between loops diagnostics



Squib/pyroswitch resistance measurement with leakage cancellation and selectable

range (10/50 Ω)



High squib/pyroswitch resistance with range from 500 Ω to 2000 Ω



SSxy, SFx and VER voltage status



High and Low side FET diagnostics



High side driver diagnostics



Loss of ground return diagnostics



High Side Safing FET diagnostics

The above diagnostic results are processed through a 10-bit Analog to digital algorithmic

converter. These tests can be addressed in two different ways, with a high level approach or

a low-level one. The main difference between the two approaches is that with the low level

approach the user is allowed to precisely control the diagnostic circuitry, also deciding the

proper timings involved in the different tests. On the other hand, the high level approach is

an automatic way of getting diagnostic results for which an internal state machine is taking

care of instructions and timings.

The following is the block diagram of the Squib/pyroswitch Diagnostics.

L9679P Datasheet(PDF) 161 Page - STMicroelectronics