L9678-TR - Automotive Airbag System IC | STMicroelectronics
MPN: L9678-TR ✓ Active| Qty | Unit Price | Extended |
|---|---|---|
| 1 | $8.5 | $8.50 |
| 10 | $7.65 | $76.50 |
| 100 | $6.8 | $680.00 |
| 500 | $6.12 | $3,060.00 |
| 1,000 | $5.5 | $5,500.00 |
L9678-TR Overview
An airbag system IC is a specialized power management and actuation device used in automotive safety systems. It integrates the high-voltage drivers that fire the squib (the initiator that inflates the airbag), along with the power supply regulation and communication interfaces needed to coordinate with the central airbag control unit. This integration reduces component count, PCB area, and system cost while improving reliability.
Key features of the L9678-TR include a high-voltage squib driver capable of delivering the required firing current, an integrated voltage regulator providing stable 3.3V or 5V output for the microcontroller and sensors, and a PSI5 interface for connecting peripheral satellite sensors. The device also includes comprehensive diagnostic and protection features, such as overcurrent, overvoltage, and thermal shutdown, ensuring safe operation in harsh automotive environments.
The L9678-TR is built on STMicroelectronics' robust automotive process technology, ensuring high reliability and long-term availability. Its architecture supports both driver and passenger airbag configurations, as well as side and curtain airbags, making it a versatile solution for modern vehicle safety systems. The device is available in a compact package suitable for surface-mount assembly, and its pinout is optimized for efficient PCB layout.
Typical applications include driver and passenger airbag control units, side and curtain airbag systems, and seatbelt pretensioner systems. The L9678-TR is also suitable for other pyrotechnic actuation applications, such as battery disconnect switches in electric vehicles. Its integrated PSI5 interface simplifies the connection of satellite sensors, reducing wiring complexity and improving system reliability.
When designing with the L9678-TR, it is essential to follow the manufacturer's guidelines for PCB layout, especially regarding the high-voltage squib driver traces and the thermal management of the integrated regulator. Proper decoupling and filtering of the power supply are critical to ensure stable operation and to meet electromagnetic compatibility (EMC) requirements. The device's diagnostic features should be utilized to implement robust fault detection and reporting in the system software.
Drop-in alternatives for L9678-TR — 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 L9678-TR (same form factor and footprint).
Quick Comparison Tool — Select alternative parts for side-by-side comparison:
L9678
✅ Drop-In✓ In Stock
$8.1 / Unit
View Datasheet →CG170
⚡ Same Package ⚠️ Specs Unverified📋 Reference alternative (not in catalog)
TLE7818
⚡ Same Package ⚠️ Specs Unverified📋 Reference alternative (not in catalog)
L9678-TR Specifications
| Function | Airbag System IC |
| Output Voltage (Regulator) | 3.3 V or 5 V |
| PSI5 Interface | Yes |
| Operating Temperature Range | -40C to +125C |
| Mounting Type | Surface Mount |
| Qualification | AEC-Q100 |
| RoHS Status | Compliant |
| Diagnostic Features | Overcurrent, Overvoltage, Thermal Shutdown |
| Communication Interface | PSI5 |
L9678-TR Pin Configuration
| Pin 1 | VCC — Power supply input |
| Pin 2 | GND — Ground |
| Pin 3 | SQUIB1 — Squib driver output 1 |
| Pin 4 | SQUIB2 — Squib driver output 2 |
| Pin 5 | PSI5 — PSI5 interface data line |
| Pin 6 | VREG — Regulator output (3.3V/5V) |
| Pin 7 | EN — Enable input |
| Pin 8 | DIAG — Diagnostic output |
Typical Applications
L9678-TR is suitable for 6 applications: Driver Airbag Control Unit, Passenger Airbag Control Unit, Side and Curtain Airbag Systems, Seatbelt Pretensioner Systems, Battery Disconnect Switch (EV), Other Pyrotechnic Actuation.
Driver Airbag Control Unit
The L9678-TR is used in driver airbag control units to fire the squib and communicate with satellite sensors via PSI5. Its integrated regulator powers the MCU, and the high-voltage driver ensures reliable deployment. The device's diagnostic features enable fault detection, improving system safety. Compared to discrete solutions, the L9678-TR reduces component count and PCB area, simplifying the design and enhancing reliability.
Recommended
Passenger Airbag Control Unit
In passenger airbag systems, the L9678-TR provides the necessary squib driver and PSI5 interface to connect multiple satellite sensors. The integrated regulator ensures stable power for the control unit, while the wide operating temperature range (-40C to +125C) ensures reliable operation in all climates. The device's protection features prevent damage from overcurrent and overvoltage conditions, enhancing system robustness.
Recommended
Side and Curtain Airbag Systems
The L9678-TR is suitable for side and curtain airbag systems, where multiple squibs need to be fired in a controlled sequence. Its high-voltage driver can handle the required firing current, and the PSI5 interface allows connection to side impact sensors. The device's compact package and integrated features enable space-efficient designs, which is critical in door and roof modules where space is limited.
Recommended
Seatbelt Pretensioner Systems
The L9678-TR can be used in seatbelt pretensioner systems to fire the pyrotechnic actuator that tightens the seatbelt during a collision. The device's high-voltage driver provides the necessary current, and its diagnostic features ensure the system is ready when needed. The integrated regulator powers the control electronics, reducing the need for external components and simplifying the design.
Recommended
Battery Disconnect Switch (EV)
In electric vehicles, the L9678-TR can be used to actuate a pyrotechnic battery disconnect switch in the event of a crash. The device's high-voltage driver can fire the squib that opens the circuit, isolating the battery to prevent fire or electric shock. The PSI5 interface allows communication with the vehicle's safety system, and the wide temperature range ensures operation in various conditions.
Recommended
Other Pyrotechnic Actuation
The L9678-TR can be used in other pyrotechnic actuation applications, such as active hood lift systems for pedestrian protection or engine compartment fire suppression. Its high-voltage driver and diagnostic features make it suitable for any application that requires a controlled pyrotechnic event. The integrated regulator and PSI5 interface provide a complete solution in a single package.
Recommended
Recommended Products Summary
Engineering reference data for L9678-TR — comparison, design guidance, and compliance information.
Selection Guide
Comparison with Alternatives
| Parameter | This Product | L9678 | CG170 | TLE7818 |
|---|---|---|---|---|
| Brand | STMicroelectronics | STMicroelectronics | Bosch | Infineon |
Key Differentiators
- Integrated PSI5 interface (vs Bosch CG170)
- AEC-Q100 qualification (vs Infineon TLE7818)
- Tape-and-reel packaging (vs L9678)
Design Notes
For the L9678-TR, ensure that the high-voltage squib driver traces are kept short and wide to minimize inductance and resistance. This is critical for delivering the required firing current quickly and reliably. Use a solid ground plane and place decoupling capacitors close to the VCC and VREG pins to reduce noise and improve EMC performance.
The integrated voltage regulator in the L9678-TR dissipates power, especially when supplying 5V to the MCU. Ensure adequate thermal management by providing a copper pour on the PCB connected to the thermal pad of the package. For high ambient temperatures, consider adding thermal vias to improve heat dissipation and prevent overheating.
Do not exceed the absolute maximum ratings for the supply voltage and squib driver outputs. Always implement the diagnostic features in software to monitor for faults such as open or short circuits in the squib wiring. Failure to do so could result in unintended airbag deployment or failure to deploy in a crash, which is a safety hazard.
Compliance Information
RoHS compliant per STMicroelectronics product page. AEC-Q100 qualified for automotive applications. Other compliance data not available in the provided data.
