L9679BTR Automotive Battery Cut-Off and Airbag IC | ST
MPN: L9679BTR ✓ ActiveL9679BTR Overview
An automotive battery cut-off circuit is an electronic subsystem that controls or isolates the vehicle battery when faults, abnormal voltage conditions, or other protection events require disconnection. An airbag-system expansion IC supports the electrical interface between the vehicle's restraint-control system and additional peripheral circuitry. The L9679BTR combines these specialized automotive functions in one application-specific semiconductor rather than functioning as a general-purpose regulator, interface converter, or discrete protection controller.
The principal verified packaging information is a 100-LQFP or TQFP100 surface-mount configuration. The package count is important because this highly integrated device provides more signal, supply, and control connections than a conventional regulator or small interface IC. System designers must use the manufacturer pinout and application schematic when assigning nets, because the complete pin names and termination details were not included in the supplied verified data. The reported 105°C temperature capability also makes package thermal performance and automotive qualification records relevant to the final design review.
Typical automotive uses include battery-protection subsystems, battery-monitoring electronics, airbag control and expansion networks, and vehicle electrical-distribution modules. In each case, the device should be evaluated as part of a qualified vehicle platform rather than selected from generic interface parameters alone. Production decisions must consider EMC behavior, diagnostic coverage, load dump protection, supply transients, and the safety requirements applicable to the restraint-control system.
A key design consideration is that an automotive battery cut-off and airbag expansion device cannot be evaluated only by nominal supply voltage or package size. Engineers should review the complete manufacturer application circuit, verify all unused-pin connections, and confirm transient ratings for the exact vehicle electrical environment. The 100-pin package also demands careful PCB layout and exposed-pad or thermal assessment where the manufacturer package drawing calls for it.
This product page consolidates verified distributor listings, package information, sourcing links, application guidance, and honest replacement analysis. It also distinguishes verified L9679BTR data from parameters that require confirmation from the STMicroelectronics datasheet before schematic release, PCB layout, qualification, or production purchasing.
Drop-in alternatives for L9679BTR — 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 L9679BTR (same form factor and footprint) — differing in Package, Pin Count.
L9679PTR
✅ Drop-In ⚠️ Specs UnverifiedContact for price
View Datasheet →L9679BTR Maximum Ratings & Electrical Characteristics
| Product Type | Automotive battery cut-off circuit and airbag system expansion IC |
| Manufacturer | STMicroelectronics |
| Device Category | Specialized power-management interface IC |
| Package | 100-pin TQFP/LQFP |
| Package Type | Surface-mount LQFP |
| Pin Count | 100 pins |
| Mounting Type | Surface mount |
| Reported Maximum Temperature | 105 °C |
| Automotive Battery Cut-Off Function | Supported |
| Airbag System Expansion Function | Supported |
L9679BTR surface-mount lqfp Pin Configuration Guide
Pin configuration for L9679BTR (surface-mount lqfp package). This power device features gate, drain, and source terminals. For non-polarized packages, refer to the manufacturer datasheet for exact pin 1 orientation and footprint details. Common applications include power supply design, motor driving, and load switching.
No detailed pinout data available for L9679BTR.
Refer to the datasheet for full pin configuration.
Typical Applications
L9679BTR is suitable for 6 applications: Automotive Battery Cut-Off Modules, Airbag Control Module Interfaces, Vehicle Electrical-Distribution Systems, Battery Monitoring and Protection, Automotive Sensor and Peripheral Expansion, High-Temperature Automotive Control Units.
Automotive Battery Cut-Off Modules
The L9679BTR fits an automotive battery cut-off module because the verified product description identifies battery-disconnection functionality as a core function. It can be evaluated alongside the battery-monitoring, sensing, and control circuitry that decides when the starter or vehicle electrical system should be isolated. The 100-pin TQFP/LQFP package provides a high connection count for integrating protection, control, and diagnostic interfaces. Designers should confirm the manufacturer battery thresholds, isolation behavior, transient limits, and diagnostic coverage in the L9679E datasheet. Layout must also follow the manufacturer reference circuit and preserve clean separation between battery and load paths, since automotive environments introduce load dump, inductive transients, temperature variation, and ground-offset conditions that cannot be evaluated from the package description alone.
Recommended
Airbag Control Module Interfaces
The L9679BTR is applicable to airbag control-module interface electronics because its verified description explicitly includes an airbag system expansion function. This makes it a candidate for a vehicle restraint-control architecture where additional peripheral interfaces must be coordinated with battery-control circuitry. The 100-pin package can support numerous external connections, but safety-critical use requires more than a matching function name. Engineers must verify diagnostic behavior, fault handling, supply behavior, and all protection mechanisms against the manufacturer datasheet and vehicle safety requirements. PCB implementation should follow the approved reference layout, especially for power distribution, grounding, signal integrity, and any interface subject to automotive transient immunity requirements.
Recommended
Vehicle Electrical-Distribution Systems
The L9679BTR can be considered for vehicle electrical-distribution subsystems that combine battery isolation with restraint-related expansion I/O. Its specialized automotive interface architecture may reduce the number of separate controllers required compared with a design assembled only from generic regulators, logic devices, and discrete protection components. The 100-pin TQFP/LQFP package nevertheless requires careful planning for routing density, thermal performance, and assembly yield. Power and signal paths should be separated according to the manufacturer application schematic, and unused connections must remain exactly as specified rather than being assigned by analogy with another L9679-family device. Because complete supply limits and transient ratings were not supplied, schematic release requires direct review of the manufacturer documentation.
Recommended
Battery Monitoring and Protection
The L9679BTR is relevant to battery-monitoring and protection designs because the verified manufacturer-related description identifies an automotive battery cut-off circuit. Its role can complement sensors, reference channels, and diagnostic logic that determine whether the battery should remain connected or be isolated. The available evidence establishes the function and 100-pin package, but it does not disclose measurement accuracy, threshold resolution, response time, or protection-current ratings. Those values must be taken from the L9679E datasheet and tested against the target vehicle's load-dump and temperature requirements. A robust implementation should also analyze the switch or relay interface, fault-state behavior, and whether the IC controls the cutoff element directly or only provides a decision and drive signal.
Recommended
Automotive Sensor and Peripheral Expansion
The L9679BTR's airbag system expansion function makes it a candidate for centralized automotive electronic modules that must connect sensors, switches, or peripheral actuator circuits to a restraint-control network. The 100-pin interface count is useful when several discrete signals and supplies must be consolidated in a compact surface-mount design. However, the supplied evidence does not identify the individual I/O types or electrical thresholds, so designers must not assume that every terminal supports the same logic level or protection level. The pin definitions, unused-pin treatment, pull-up or pull-down requirements, and timing behavior should be transcribed directly from the manufacturer documentation. Signal-integrity checks should include edge rates, return paths, and any external communication implemented around the expansion interface.
Recommended
High-Temperature Automotive Control Units
The L9679BTR may suit high-temperature automotive control units where battery protection and supplemental-restraint expansion functions are both required. The supplied distributor-related material reports a maximum temperature of 105 °C, making thermal verification an explicit design step. Although the package is a 100-pin TQFP/LQFP, the reported temperature does not alone establish the complete operating range or automotive qualification grade. Engineers should review maximum junction temperature, ambient derating, package thermal resistance, and the board's copper and airflow conditions. Layout should provide a dependable thermal path if the manufacturer package includes an exposed thermal pad, while assembly and inspection plans should account for the fine-pitch package and the automotive sector's traceability requirements.
Recommended
Recommended Products Summary
Engineering reference data for L9679BTR — comparison, design guidance, and compliance information.
Selection Guide
Comparison with Alternatives
| Parameter | This Product | L9679PTR |
|---|---|---|
| Package | TQFP-100 | TQFP-100 |
| Brand | STMicroelectronics | STMicroelectronics |
| Pin Count | 100 pins | 100 pins |
| Mounting Type | Surface mount | Surface mount |
Key Differentiators
- Integrated automotive battery and restraint-control functions (vs L9679PTR)
- High pin count for vehicle-specific integration (vs L9679PTR)
- Reported high-temperature capability (vs L9679PTR)
Design Notes
Use the manufacturer reference layout for the 100-pin TQFP/LQFP device and preserve the documented separation between battery-connected power paths, protected I/O, and logic signals. Place protection and filtering components directly at the pins that connect to external harness or board interfaces. Confirm every unused pin against the datasheet because assigning a no-connect state by analogy with another L9679-family variant can create an unreviewed current path or unsafe operating state.
Validate the battery-side supply path against load dump, reverse polarity, jump-start, and other automotive transients before committing the board layout. The supplied verified data does not include input-voltage limits or protection thresholds, so external network design must use the manufacturer application circuit rather than generic 12-V assumptions. Keep high-current battery switching energy away from sensitive signal paths and use the recommended protection components and grounding strategy.
The supplied distributor-related material reports a 105 °C maximum temperature for the L9679BTR. That figure is not a complete operating-temperature specification, so confirm the grade-specific limits and junction-temperature conditions in the manufacturer datasheet. At assembly, evaluate the TQFP thermal path using the actual PCB copper, adjacent heat sources, airflow, and board construction rather than relying on package size alone.
Do not substitute an automotive IC solely because the package, pin count, and function description appear similar. The L9679BTR combines battery cut-off and airbag expansion responsibilities, so supply levels, diagnostic behavior, fault states, protection thresholds, and qualification records may be critical to system safety. Obtain the complete manufacturer ordering and application documents and document any approved second-source deviation before layout release.
Compliance Information
The supplied verified data does not provide explicit RoHS, REACH, AEC-Q100, lead-free, halogen-free, or conflict-minerals declarations. Compliance must be confirmed using the current STMicroelectronics product page, material declaration, or authorized distributor records.
