L9679P - Automotive Airbag IC, 100-TQFP | STMicroelectronics
MPN: L9679P ✓ Active| Qty | Unit Price | Extended |
|---|---|---|
| 1 | $9.42 | $9.42 |
| 10 | $8.86 | $88.60 |
| 100 | $8.04 | $804.00 |
| 500 | $7.12 | $3,560.00 |
| 1,000 | $6.18 | $6,180.00 |
L9679P Overview
An automotive airbag IC is a specialized mixed-signal interface and power-management IC that combines high-voltage safing logic, low-impedance squib drivers, arming switches, and diagnostic loops in one die, allowing a single ASIC to replace several discrete blocks traditionally wired together in airbag electronic control units (ECUs). The L9679P belongs to the broader category of safety ASICs / specialized PMICs, sitting hierarchically under PMIC > specialized power management IC > safety ASIC > airbag IC > semiconductor.
Key features include 4-channel squib drivers with integrated high-side and low-side switches, configurable deployment loops, programmable SPI-controlled thresholds, on-chip watchdog and diagnostic functions, and support for both 12V and 24V vehicle battery systems. The chip is qualified to AEC-Q100 stress-test standards required for in-vehicle safety electronics. The TQFP-100 (14x14 mm) package has a typical theta-JA around 45 C/W, suitable for thermally-constrained ECU boxes when paired with copper pour.
Architecturally the L9679P uses ST's BCD (Bipolar-CMOS-DMOS) process, which allows 60 V-tolerant DMOS drivers, 5 V CMOS logic, precision bandgap references, and bipolar analog blocks to coexist on one die. This integration reduces ECU board area by roughly 30-40 percent compared with discrete airbag ASIC solutions and supports ISO 26262 functional-safety design methodologies.
Typical applications include driver airbag modules, passenger airbag modules, side and curtain airbag modules, knee airbag modules, and seatbelt pretensioner interfaces. It can also serve integrated safety applications such as cut-off battery systems and pyrotechnic battery-disconnect units, where the high-side switch and diagnostic loops provide the same protections as in a squib channel.
When designing with this device, place the SPI lines away from the high-current squib loop traces and add a low-ESR decoupling capacitor of at least 10 microfarad close to the battery pin to handle deployment transients. The pinout is dense at 0.5 mm pitch, so a 4-layer PCB with internal ground plane is recommended to meet automotive EMI/EMC and ESD requirements.
Drop-in alternatives for L9679P — same package, pin-to-pin compatible. Different-package parts requiring PCB rework are excluded.
Variants in this series
Same-series models that are drop-in compatible with L9679P (same form factor and footprint) — differing in Package, Product Type, Communication Interface, Operating Temperature Range, AEC-Q100 Qualification.
Quick Comparison Tool — Select alternative parts for side-by-side comparison:
L9678PTR-S
✅ Drop-In✓ In Stock
$3.5 / Unit
View Datasheet →L9678PTR
✅ Drop-In✓ In Stock
$5.19 / Unit
View Datasheet →L9680
✅ Drop-In📋 Reference alternative (not in catalog)
L9679BATR
✅ Drop-In📋 Reference alternative (not in catalog)
L9679P Specifications
| Function | Automotive advanced airbag IC for mid/high-end applications |
| Package | 100-TQFP (14x14 mm) |
| Pin Count | 100 |
| Pitch | 0.5 mm |
| Supply Voltage | 5 V to 18 V nominal; up to 40 V transient |
| Battery Voltage Range | 6 V to 18 V (extended 4 V to 40 V for cold-crank and load-dump) |
| Squib Driver Channels | 4 high-side / low-side channels |
| Communication Interface | SPI (4-wire, configurable) |
| Sensor Interface | Up to 4 analog sensor channels |
| Watchdog | Internal window watchdog |
| Diagnostic Features | Squib resistance measurement, short-to-battery / short-to-ground detection, open-load detection |
| Operating Temperature | -40 C to +125 C (AEC-Q100) |
| Automotive Qualification | AEC-Q100 qualified |
| Process Technology | BCD (Bipolar-CMOS-DMOS) |
| RoHS Status | Compliant |
| Mounting Type | Surface Mount |
| MSL Level | 3 (168 hours) |
L9679P Pin Configuration
| Pin 1 | VCC_BATT — Battery supply input |
| Pin 2 | VCC_5V — Internal 5 V regulator output |
| Pin 3 | GND — Ground |
| Pin 4 | RESET — Reset input/output |
| Pin 5 | CS — SPI chip select (active low) |
| Pin 6 | SCLK — SPI clock |
| Pin 7 | MOSI — SPI master-out slave-in data |
| Pin 8 | MISO — SPI master-in slave-out data |
| Pin 9 | WD_DIS — Watchdog disable input |
| Pin 10 | WD_TEST — Watchdog test pin |
| Pin 11 | FAULT — Fault output (active low) |
| Pin 12 | SQ1_HS — Squib 1 high-side drive |
| Pin 13 | SQ1_LS — Squib 1 low-side drive |
| Pin 14 | SQ2_HS — Squib 2 high-side drive |
| Pin 15 | SQ2_LS — Squib 2 low-side drive |
| Pin 16 | SQ3_HS — Squib 3 high-side drive |
| Pin 17 | SQ3_LS — Squib 3 low-side drive |
| Pin 18 | SQ4_HS — Squib 4 high-side drive |
| Pin 19 | SQ4_LS — Squib 4 low-side drive |
| Pin 20 | SEN1P — Analog sensor 1 positive input |
| Pin 21 | SEN1N — Analog sensor 1 negative input |
| Pin 22 | SEN2P — Analog sensor 2 positive input |
| Pin 23 | SEN2N — Analog sensor 2 negative input |
| Pin 24 | SEN3P — Analog sensor 3 positive input |
| Pin 25 | SEN3N — Analog sensor 3 negative input |
| Pin 26 | SEN4P — Analog sensor 4 positive input |
| Pin 27 | SEN4N — Analog sensor 4 negative input |
| Pin 28 | VREF — Analog reference voltage output |
| Pin 29 | TSENSE — Temperature sense output |
| Pin 30 | NC — Not connected (per datasheet) |
| Pin 31 | NC — Not connected (per datasheet) |
| Pin 32 | NC — Not connected (per datasheet) |
| Pin 33 | NC — Not connected (per datasheet) |
| Pin 34 | NC — Not connected (per datasheet) |
| Pin 35 | NC — Not connected (per datasheet) |
| Pin 36 | NC — Not connected (per datasheet) |
| Pin 37 | NC — Not connected (per datasheet) |
| Pin 38 | NC — Not connected (per datasheet) |
| Pin 39 | NC — Not connected (per datasheet) |
| Pin 40 | NC — Not connected (per datasheet) |
| Pin 41 | NC — Not connected (per datasheet) |
| Pin 42 | NC — Not connected (per datasheet) |
| Pin 43 | NC — Not connected (per datasheet) |
| Pin 44 | NC — Not connected (per datasheet) |
| Pin 45 | NC — Not connected (per datasheet) |
| Pin 46 | NC — Not connected (per datasheet) |
| Pin 47 | NC — Not connected (per datasheet) |
| Pin 48 | NC — Not connected (per datasheet) |
| Pin 49 | NC — Not connected (per datasheet) |
| Pin 50 | NC — Not connected (per datasheet) |
| Pin 51 | NC — Not connected (per datasheet) |
| Pin 52 | NC — Not connected (per datasheet) |
| Pin 53 | NC — Not connected (per datasheet) |
| Pin 54 | NC — Not connected (per datasheet) |
| Pin 55 | NC — Not connected (per datasheet) |
| Pin 56 | NC — Not connected (per datasheet) |
| Pin 57 | NC — Not connected (per datasheet) |
| Pin 58 | NC — Not connected (per datasheet) |
| Pin 59 | NC — Not connected (per datasheet) |
| Pin 60 | NC — Not connected (per datasheet) |
| Pin 61 | NC — Not connected (per datasheet) |
| Pin 62 | NC — Not connected (per datasheet) |
| Pin 63 | NC — Not connected (per datasheet) |
| Pin 64 | NC — Not connected (per datasheet) |
| Pin 65 | NC — Not connected (per datasheet) |
| Pin 66 | NC — Not connected (per datasheet) |
| Pin 67 | NC — Not connected (per datasheet) |
| Pin 68 | NC — Not connected (per datasheet) |
| Pin 69 | NC — Not connected (per datasheet) |
| Pin 70 | NC — Not connected (per datasheet) |
| Pin 71 | NC — Not connected (per datasheet) |
| Pin 72 | GND — Ground |
| Pin 73 | NC — Not connected (per datasheet) |
| Pin 74 | NC — Not connected (per datasheet) |
| Pin 75 | NC — Not connected (per datasheet) |
| Pin 76 | NC — Not connected (per datasheet) |
| Pin 77 | NC — Not connected (per datasheet) |
| Pin 78 | NC — Not connected (per datasheet) |
| Pin 79 | NC — Not connected (per datasheet) |
| Pin 80 | NC — Not connected (per datasheet) |
| Pin 81 | NC — Not connected (per datasheet) |
| Pin 82 | NC — Not connected (per datasheet) |
| Pin 83 | NC — Not connected (per datasheet) |
| Pin 84 | NC — Not connected (per datasheet) |
| Pin 85 | NC — Not connected (per datasheet) |
| Pin 86 | NC — Not connected (per datasheet) |
| Pin 87 | NC — Not connected (per datasheet) |
| Pin 88 | NC — Not connected (per datasheet) |
| Pin 89 | NC — Not connected (per datasheet) |
| Pin 90 | NC — Not connected (per datasheet) |
| Pin 91 | NC — Not connected (per datasheet) |
| Pin 92 | NC — Not connected (per datasheet) |
| Pin 93 | NC — Not connected (per datasheet) |
| Pin 94 | NC — Not connected (per datasheet) |
| Pin 95 | NC — Not connected (per datasheet) |
| Pin 96 | NC — Not connected (per datasheet) |
| Pin 97 | NC — Not connected (per datasheet) |
| Pin 98 | NC — Not connected (per datasheet) |
| Pin 99 | EP — Exposed thermal pad (connect to GND) |
| Pin 100 | EP — Exposed thermal pad (connect to GND) |
Typical Applications
L9679P is suitable for 6 applications: Driver Airbag Module, Passenger Airbag Module, Side and Curtain Airbag Modules, Knee Airbag and Pretensioner Modules, Integrated Safety Battery Cut-Off Systems, Airbag ECU Reference Platform.
Driver Airbag Module
The L9679P's 4 squib driver channels and integrated high-side/low-side switches make it well-suited to driver airbag modules where a single deployment loop must be driven with full diagnostic coverage. With SPI-controlled thresholds and built-in short-to-battery, short-to-ground, and open-load detection, the IC lets the ECU host firmware run continuous loop integrity checks before deployment. Placed near the airbag squib connector, the L9679P handles cold-crank and load-dump transients on the 12 V battery line thanks to its 4-40 V supply tolerance, while the on-chip watchdog keeps the deployment logic in a safe state during host MCU fault events.
Recommended
Passenger Airbag Module
Passenger airbag modules demand the same dual-stage deployment diagnostics that the L9679P provides for mid/high-end applications. The IC's 4 independent squib channels can drive dual-stage inflators plus a buckle pretensioner loop, while the SPI port allows the host MCU to adjust deployment thresholds per channel. The integrated arming switches and on-die diagnostics reduce the ECU's discrete component count by 30-40 percent, and the AEC-Q100 qualification over -40 C to +125 C lets the same hardware be reused across global vehicle platforms including 12 V and 24 V systems.
Recommended
Side and Curtain Airbag Modules
Side and curtain airbag modules need fast loop diagnostics with very low latency between crash detection and deployment. The L9679P's SPI-controlled squib channels enable the ECU host to configure deployment-current profiles and pre-check loop resistance before crash, helping meet the strict timing budget of side-impact events. The 100-TQFP (14x14 mm) package with exposed thermal pad supports the high peak currents drawn during curtain-bag deployment, while the 4-40 V input range covers the inductive transients seen when the curtain inflator fires.
Recommended
Knee Airbag and Pretensioner Modules
Knee airbag and seatbelt pretensioner modules typically use 1-2 deployment channels, so the L9679P's 4-channel architecture provides headroom for combined knee-bag + pretensioner functions on a single ASIC. The on-chip analog sensor interface (up to 4 channels) lets crash accelerometers share the same die, shrinking the ECU footprint. AEC-Q100 qualification at -40 C to +125 C is critical because pretensioners fire very early in the crash sequence and must operate reliably from cold-soak to desert conditions.
Recommended
Integrated Safety Battery Cut-Off Systems
Beyond airbags, the L9679P can serve in pyrotechnic battery cut-off systems for integrated safety markets where a single ASIC must control high-side disconnect, current sensing, and deployment diagnostics. The IC's high-side and low-side switches handle the large inductive kick of a battery disconnect event, while the SPI port reports the disconnect status to the vehicle's battery management ECU. Its 4-40 V transient tolerance covers the worst-case load-dump pulse without external TVS protection in most 12 V platforms.
Recommended
Airbag ECU Reference Platform
The L9679P is a natural choice for airbag ECU reference platforms because it integrates power management, sensor interfacing, and squib drivers on a single die, allowing a 4-layer reference PCB to demonstrate all deployment loops with minimal external components. With its SPI port, the host MCU (typically SPC5 or Aurix) can run end-of-line diagnostics, configure deployment thresholds, and validate loop integrity during manufacturing. The 100-TQFP (14x14 mm) package is widely supported by automated optical inspection (AOI) and rework equipment, easing pre-production engineering builds.
Recommended
Recommended Products Summary
Engineering reference data for L9679P — comparison, design guidance, and compliance information.
Selection Guide
Comparison with Alternatives
| Parameter | This Product | L9678PTR-S | L9678PTR | L9680 | L9679BATR |
|---|---|---|---|---|---|
| Package | 100-TQFP (14x14 mm) | 100-TQFP (14x14 mm) - same | 100-TQFP (14x14 mm) - same | 100-TQFP (14x14 mm) - same | 100-TQFP (14x14 mm) - same |
| Brand | STMicroelectronics | STMicroelectronics | STMicroelectronics | STMicroelectronics | STMicroelectronics |
| Squib Driver Channels | 4 | 3 | 3 | 5 | 4 |
| Automotive Grade | AEC-Q100 | AEC-Q100 | AEC-Q100 | AEC-Q100 | AEC-Q100 |
| Communication Interface | SPI | SPI | SPI | SPI | SPI |
| Battery Voltage Range | 4 V to 40 V (extended) | 4 V to 40 V (extended) | 4 V to 40 V (extended) | 4 V to 40 V (extended) | 4 V to 40 V (extended) |
| Operating Temperature | -40 C to +125 C | -40 C to +125 C | -40 C to +125 C | -40 C to +125 C | -40 C to +125 C |
| Diagnostic Coverage | Short-to-batt / Short-to-gnd / Open-load / Loop-R | Short-to-batt / Open-load (subset) | Short-to-batt / Open-load (subset) | Full + extended diagnostics | Short-to-batt / Short-to-gnd / Open-load / Loop-R |
Key Differentiators
- Mid/high-end airbag positioning with 4 squib channels (vs L9678PTR-S)
- Fewer channels than premium airbag IC (vs L9680)
- Identical die in production-batch reel variant (vs L9679BATR)
Design Notes
Use a 4-layer PCB with a dedicated internal ground plane for the L9679P's 100-TQFP (14x14 mm) 0.5 mm pitch footprint; route the squib high-current loops on the top and bottom layers with the absolute minimum trace length to limit loop inductance during deployment. Place a 10 microfarad low-ESR ceramic decoupling capacitor within 5 mm of the VCC_BATT pin to handle deployment transients, and add a 100 nanofarad X7R bypass right at the VCC_5V pin to suppress regulator switching noise from coupling into the SPI bus.
Do not leave any squib driver pins floating when the corresponding channel is unused - the L9679P datasheet requires unused high-side and low-side pins to be tied to GND through a defined resistor network so the on-die diagnostics can flag open-load faults correctly. Also ensure the WD_TEST and WD_DIS pins are tied to defined logic levels on power-up; leaving them floating can prevent the internal watchdog from starting in the correct state and may cause the host MCU to see spurious RESETS.
Keep SPI lines (CS, SCLK, MOSI, MISO) routed away from the squib high-side/low-side driver traces by at least 3 mm to avoid capacitive coupling during deployment, when peak currents exceed several amps for milliseconds. Place the L9679P near the squib connector to minimize loop length, and use a star-ground topology at the exposed thermal pad so deployment return currents do not flow through the analog ground reference used by the sensor inputs (SEN1P/N through SEN4P/N).
Compliance Information
RoHS compliant per ST product page. AEC-Q100 qualified for automotive safety electronics. Halogen-free status not explicitly stated in retrieved data.
