STMicroelectronics L9679P

Overview

L9679P from STMicroelectronics is an AEC-Q100 qualified automotive airbag system IC integrating eight-channel squib/pyroswitch drivers, dual boost regulators (ERBOOST at 23 V/33 V and SYNCBOOST at 12 V/14.75 V), three buck regulators (SATBUCK, VCC, VSF), energy reserve crossover switch (3 Ω, 912 mA), PSI-5 remote sensor interface, and 32-bit SPI communications - deployed in mid/high-end airbag control units for reliable deployment under crash conditions.

For engineers reviewing the L9679P datasheet, L9679P pinout, L9679P application, or L9679P equivalent, this page delivers verified technical context on its multi-regulator power architecture, 8-channel pyro driver diagnostics (R_measure, STB, STG, leakage), safing logic configurability, and TQFP100 package implementation - critical for functional safety validation and ASIL-B system design.

Technical Context

The L9679P implements a fault-tolerant power management architecture with four independent switching regulators operating at 1.882 MHz: ERBOOST supplies energy reserve capacitors (23 V/33 V ±5%), SYNCBOOST powers PSI-5 sync pulses (12 V/14.75 V), SATBUCK delivers 7.2 V/9 V ±4% to remote sensors, and VCC provides 3.3 V/5.0 V ±3% to MCU subsystems. All regulators include capacitor ESR and value diagnostics.

Its deployment subsystem features eight HSD/LSD drivers with programmable current profiles, real-time squib resistance measurement (R_measure), STB/STG diagnostics, and high/low-side FET tests. Safing logic is user-customizable via SPI-configurable thresholds and temporal/algorithmic watchdog timers (WD1 and WD2) supporting ASIL-B compliance.

Key Specifications

Pinout & Package

TQFP100 exposed pad down (14 mm × 14 mm × 1.0 mm), RoHS-compliant, thermal pad optimized for PCB heat dissipation in airbag control module assemblies.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar airbag system controller applications.

Compared with MC33972 and RAA271000, the L9679P uniquely integrates ERBOOST, SYNCBOOST, SATBUCK, and PSI-5 interface in one AEC-Q100 package - reducing BOM count and PCB area while enabling distributed sensor topologies without gateway dependency.

Availability

L9679P is available at Aetrix Electronics and suitable for mid/high-end airbag systems, cut-off battery systems, and pyro fuse/switch management requiring stable component supply, long-term automotive lifecycle support, and ASIL-B compliant design assurance.

Supply support for L9679P includes scheduled delivery planning, volume procurement assistance, BOM continuity management, traceable sourcing, and lifecycle availability coordination for OEM customers, industrial embedded developers, connected-device designers, and electronics production programs.

Manufacturer

STMicroelectronics is a global semiconductor leader specializing in automotive-grade analog, power, and microcontroller solutions with deep expertise in functional safety and ASIL-certified IC development.

The L9679P belongs to ST's SAFETYline portfolio of airbag system ICs, engineered specifically for ISO 26262-compliant restraint control units where integrated diagnostics, multi-regulator power management, and configurable safing logic are mandatory.

FAQ

What is the maximum allowable deployment voltage for the L9679P squib drivers?

The L9679P squib drivers support a maximum deployment voltage of 25 V, as specified in Section 8.2 of the DS11627 Rev 8 datasheet. This rating applies to both high-side and low-side outputs during active deployment, and is maintained across the full operating temperature range (−40 °C to +95 °C). The device includes built-in short-to-battery protection that clamps output voltage above this limit to prevent damage to connected pyro devices.

Does the L9679P support daisy-chained PSI-5 sensors?

Yes, the L9679P supports daisy-chained PSI-5 satellite sensors via its two dedicated PSI-5 channels (PSI5_CH1 and PSI5_CH2), each capable of driving up to eight sensors in series. The interface implements LCID and CRC error detection per frame (Section 9.1.2), and includes automatic sensor enumeration and fault isolation logic to identify open or shorted links in the chain without host MCU intervention.

How does the L9679P perform squib resistance measurement?

The L9679P performs squib resistance measurement (R_measure) using integrated current sources and ADC-based voltage sensing on each DEPx_H/DEPx_L pair. As described in Section 18.17.1, it applies a known test current, measures resulting voltage drop, and calculates resistance with ±5% accuracy - all while isolating the squib from energy reserve and deployment paths to ensure safety during diagnostics.

Is the L9679P pin-compatible with earlier ST airbag ICs like L9674?

No, the L9679P is not pin-compatible with the L9674. It uses a 100-pin TQFP package with different pin assignments for regulators (e.g., separate ERBOOST_OUT and SYNCBOOST_OUT), PSI-5 interfaces, and GPO configurations. Migration requires PCB redesign and firmware adaptation due to expanded feature set, updated SPI register map, and enhanced diagnostic capabilities documented in DS11627 Rev 8.