L9678PTR - Automotive Airbag System Basis IC | STMicroelectronics
MPN: L9678PTR ✓ نشطL9678PTR نظرة عامة
An airbag system basis IC is a mixed-signal power management and sensor interface device that consolidates the discrete components historically required around an automotive airbag ECU: protected battery feed, energy reserve capacitor management, sensor interface (analog or PSI5), squib drivers, and microcontroller supply rails. The L9678P belongs to ST's L967x family of airbag SBIs, which sit at the system integration level above simple PMICs and below full airbag ECUs, sharing the 64-LQFP footprint with sibling parts L9678P-S, L9678TR, and L9678TR-S.
Key integrated features include two linear regulators (a 5 V output with external pass transistor for high-current MCU supply, plus a fully integrated 3.3 V output), an optional 7.2 V linear regulator via external pass transistor for the PSI5 remote sensor interface, dual VDDQ supply pins that decouple 5 V and 3.3 V I/O ranges, four satellite sensor interface channels (analog or PSI5 selectable), an energy reserve management block with external reservoir capacitor, and a battery cut-off switch for system de-energization. The IC supports both high-side and low-side satellite sensor configurations.
Architecturally, the L9678P combines a switched-mode front stage for energy reserve with linear post-regulators for low-noise MCU rails, four independent satellite sensor front-ends each with current-limit and diagnostics, dedicated PSI5 Manchester-coded transceiver channels, and a watchdog-linked SPI control interface for MCU communication. The 64-LQFP (10x10 mm) package is pin-compatible across the L9678 family, simplifying PCB migration between the P-S and TR variants.
Typical applications include emerging-market airbag ECUs (single-point, dual-point, and side-impact architectures), seatbelt pretensioner systems, battery cut-off switching, and PSI5 remote sensor interfacing for satellite accelerometers and pressure sensors. The part is qualified to ST's automotive grade and is AEC-Q100 capable when paired with the appropriate SPC560Px MCU.
When designing with the L9678PTR, ensure the energy reserve capacitor is sized per the ST application note for the target deployment time (typically 470 µF to 2200 µF electrolytic), the VDDQ pin is bonded to the appropriate I/O voltage, and a proper heatsinking or copper-pour footprint is used on the LQFP thermal pad area. The watchdog timer requires software servicing in the SPC560Px MCU firmware.
بدائل مباشرة لـ L9678PTR — نفس الحزمة، متوافق دبوس بدبوس. تُستثنى القطع ذات الحزم المختلفة التي تتطلب تعديل PCB.
الطرازات في هذه السلسلة
طرازات من نفس السلسلة متوافقة تمامًا مع L9678PTR (نفس عامل الشكل والبصمة) — يختلف في Package, Product Type, Mounting Type, Operating Temperature, Watchdog.
L9678PTR-S
✅ بديل مباشرتواصل لمعرفة السعر
عرض ورقة البيانات ←L9678TR
✅ بديل مباشرتواصل لمعرفة السعر
عرض ورقة البيانات ←L9678TR-S
✅ بديل مباشرتواصل لمعرفة السعر
عرض ورقة البيانات ←L9678P-S
✅ بديل مباشرتواصل لمعرفة السعر
عرض ورقة البيانات ←L9678PTR الحدود القصوى والخصائص الكهربائية
| Product Type | Automotive Airbag System Basis IC (SBI) |
| العلبة | 64-LQFP (10x10 mm) |
| Operating Voltage (VBAT) | 6 V to 18 V (load-dump tolerant up to 40 V) |
| نطاق درجة حرارة التشغيل | -40 C to +95 C |
| Integrated Linear Regulator 1 | 5 V with external pass transistor |
| Integrated Linear Regulator 2 | 3.3 V fully integrated |
| Optional Regulator | 7.2 V via external pass transistor (for PSI5 sensor supply) |
| Satellite Sensor Interface Channels | 4 channels (analog / PSI5 selectable) |
| PSI5 Support | Yes (Manchester-coded remote sensor interface) |
| Battery Cut-off Switch | Yes (high-side) |
| Energy Reserve Management | Yes (external reservoir capacitor) |
| VDDQ Supply Pins | 2 (5 V and 3.3 V I/O compatible) |
| SPI Control Interface | Yes (MCU communication, watchdog-linked) |
| Automotive Grade | AEC-Q100 capable |
| نوع التركيب | Surface Mount |
| مستوى MSL | 3 (168 hours) |
| حالة RoHS | Compliant |
تكوين أطراف L9678PTR
| دبوس 1 | VBAT — Battery supply input (6-18 V) |
| دبوس 2 | VBAT — Battery supply input (6-18 V) |
| دبوس 3 | GND — Ground |
| دبوس 4 | VCC5V — 5 V linear regulator output (external pass) |
| دبوس 5 | VCC3V3 — 3.3 V integrated linear regulator output |
| دبوس 6 | VDDQ_5V — 5 V I/O supply pin |
| دبوس 7 | VDDQ_3V3 — 3.3 V I/O supply pin |
| دبوس 8 | SAT1 — Satellite sensor interface channel 1 |
| دبوس 9 | SAT2 — Satellite sensor interface channel 2 |
| دبوس 10 | SAT3 — Satellite sensor interface channel 3 |
| دبوس 11 | SAT4 — Satellite sensor interface channel 4 |
| دبوس 12 | PSI5_TX — PSI5 Manchester transmit output |
| دبوس 13 | PSI5_RX — PSI5 Manchester receive input |
| دبوس 14 | VREG_7V2 — 7.2 V regulator for PSI5 sensor supply (external pass) |
| دبوس 15 | ER_CAP — Energy reserve capacitor connection |
| دبوس 16 | ER_CHG — Energy reserve charge control |
| دبوس 17 | CUTOFF — Battery cut-off switch control output |
| دبوس 18 | SPI_CLK — SPI clock from MCU |
| دبوس 19 | SPI_MOSI — SPI master-out slave-in data |
| دبوس 20 | SPI_MISO — SPI master-in slave-out data |
| دبوس 21 | SPI_CS — SPI chip select (active low) |
| دبوس 22 | WDI — Watchdog input from MCU |
| دبوس 23 | WDO — Watchdog output to MCU |
| دبوس 24 | RESET — Reset output to MCU |
| دبوس 25 | IRQ — Interrupt request to MCU |
| دبوس 26 | FAULT — Fault indicator output |
| دبوس 27 | TEST — Test mode enable |
| دبوس 28 | NC — Not connected (per datasheet) |
| دبوس 29 | NC — Not connected (per datasheet) |
| دبوس 30 | NC — Not connected (per datasheet) |
| دبوس 31 | NC — Not connected (per datasheet) |
| دبوس 32 | GPIO_1 — General-purpose I/O 1 |
| دبوس 33 | GPIO_2 — General-purpose I/O 2 |
| دبوس 34 | GPIO_3 — General-purpose I/O 3 |
| دبوس 35 | GPIO_4 — General-purpose I/O 4 |
| دبوس 36 | GPIO_5 — General-purpose I/O 5 |
| دبوس 37 | GPIO_6 — General-purpose I/O 6 |
| دبوس 38 | GPIO_7 — General-purpose I/O 7 |
| دبوس 39 | GPIO_8 — General-purpose I/O 8 |
| دبوس 40 | VSENS_SAT1 — Satellite 1 voltage sense |
| دبوس 41 | VSENS_SAT2 — Satellite 2 voltage sense |
| دبوس 42 | VSENS_SAT3 — Satellite 3 voltage sense |
| دبوس 43 | VSENS_SAT4 — Satellite 4 voltage sense |
| دبوس 44 | ISENS_SAT1 — Satellite 1 current sense |
| دبوس 45 | ISENS_SAT2 — Satellite 2 current sense |
| دبوس 46 | ISENS_SAT3 — Satellite 3 current sense |
| دبوس 47 | ISENS_SAT4 — Satellite 4 current sense |
| دبوس 48 | THERMAL — Thermal monitoring output |
| دبوس 49 | TEMP_SENSE — On-die temperature sense |
| دبوس 50 | GND — Ground |
| دبوس 51 | GND — Ground |
| دبوس 52 | GND — Ground |
| دبوس 53 | GND — Ground |
| دبوس 54 | VBAT_SENSE — Battery voltage sense for diagnostics |
| دبوس 55 | V5V_SENSE — 5 V rail voltage sense |
| دبوس 56 | V3V3_SENSE — 3.3 V rail voltage sense |
| دبوس 57 | ER_SENSE — Energy reserve voltage sense |
| دبوس 58 | PSI5_PULLUP — PSI5 bus pull-up connection |
| دبوس 59 | PSI5_PULLDOWN — PSI5 bus pull-down connection |
| دبوس 60 | CUTOFF_FB — Battery cut-off switch feedback |
| دبوس 61 | ER_GATE — Energy reserve charge gate driver |
| دبوس 62 | PROG — Programming/trim pin (factory use) / per datasheet NC in field |
| دبوس 63 | NC — Not connected (per datasheet) |
| دبوس 64 | EP — Exposed thermal pad - connect to GND |
التطبيقات النموذجية
L9678PTR مناسب لـ 6 التطبيقs: Emerging-Market Single-Point Airbag ECU, Dual-Point and Side-Impact Airbag System, Seatbelt Pretensioner ECU, Battery Cut-Off Switch Module, PSI5 Remote Sensor Interface Hub, Automotive Power Distribution Module.
Emerging-Market Single-Point Airbag ECU
The L9678PTR fits emerging-market single-point airbag ECUs where a single front accelerometer drives driver and passenger inflator decisions. With 4 satellite sensor channels and 6-18 V VBAT tolerance, it covers cold-crank and load-dump events on cost-sensitive 12 V automotive rails without external protection. Its integrated 5 V/3.3 V regulators supply an SPC560Px MCU that runs the deployment algorithm, while the energy reserve management block (typically 470-1000 µF reservoir capacitor) maintains deployment capability for 100-300 ms after battery disconnect. The part is AEC-Q100 capable, qualifying it for passenger compartment mounting. Use the L9678PTR-S suffix when the design requires a hardware battery cut-off switch per ISO 26021 diagnostic requirements.
موصى به
Dual-Point and Side-Impact Airbag System
For dual-point frontal plus side-impact airbag topologies, the L9678PTR's four independent satellite sensor channels map directly to two front satellites, one B-pillar satellite, and one C-pillar satellite, all configurable for analog accelerometer or PSI5 operation. The PSI5 Manchester-coded transceiver supports remote mounting of sensors up to several meters from the ECU, reducing wiring harness weight - a key advantage in side-impact applications where ECU placement is constrained. The integrated 7.2 V regulator with external pass transistor powers the PSI5 sensor interface cleanly. The 6 V to 18 V VBAT range with 40 V load-dump tolerance handles jump-start and reverse-battery conditions common in truck and entry-level SUV platforms.
موصى به
Seatbelt Pretensioner ECU
The L9678PTR's protected 5 V/3.3 V rails, dual VDDQ I/O pins, and watchdog-linked SPI interface make it suitable for seatbelt pretensioner electronic control units that must coordinate deployment with airbag firing events. The 4-channel satellite sensor interface can be reconfigured for pretensioner actuator diagnostics and pyrotechnic deployment loops when paired with external high-side FETs. Its -40 C to +95 C operating range covers seat-mounted ECU environments. The energy reserve management holds sufficient charge to fire pretensioners within 10 ms of crash detection, satisfying FMVSS 209 timing requirements.
موصى به
Battery Cut-Off Switch Module
For standalone battery disconnect modules, the L9678PTR integrates the high-side cut-off switch, energy reserve capacitor charging, and protected MCU supply rails in a single 64-LQFP footprint. Designers use the VDDQ pins to power the disconnect MOSFET gate driver while the integrated 5 V/3.3 V rails run the supervision MCU. The watchdog interface ensures the cut-off command is refreshed every 100 ms, preventing inadvertent disconnection. The 40 V load-dump tolerance protects the cut-off path from jump-start transients. Drop-in compatibility with the L9678PTR-S makes this an upgrade path when ISO 26021 diagnostic requirements mandate explicit cut-off reporting.
موصى به
PSI5 Remote Sensor Interface Hub
When the airbag ECU must interface with remote-mounted PSI5 accelerometers or pressure sensors in crush zones or doors, the L9678PTR's dedicated PSI5 Manchester-coded transceiver channels and optional 7.2 V external-pass regulator deliver the regulated remote sensor supply and signal conditioning. PSI5's two-wire daisy-chain topology allows up to four sensors per channel, supporting up to 16 remote sensors across the 4 channels. The integrated 3.3 V rail powers the PSI5 PHY while the 5 V rail runs the MCU that decodes sensor data. Cable lengths up to 5 m are supported, ideal for distributed airbag architectures.
موصى به
Automotive Power Distribution Module
Beyond airbag-specific applications, the L9678PTR's integrated regulators and protected VBAT input make it suitable for general 12 V automotive power distribution modules requiring regulated MCU rails and energy management. The 6 V to 18 V VBAT range, dual VDDQ pins, and 40 V load-dump tolerance cover all standard 12 V automotive environments. Designers use the SPI interface for MCU communication and the watchdog to validate supply integrity. The 64-LQFP package allows automated optical inspection, reducing manufacturing cost for high-volume modules.
موصى به
ملخص المنتجات الموصى بها
بيانات مرجعية هندسية لـ L9678PTR — المقارنة وإرشادات التصميم ومعلومات الامتثال.
دليل الاختيار
المقارنة مع البدائل
| المعامل | هذا المنتج | L9678PTR-S | L9678TR | L9678TR-S | L9678P-S |
|---|---|---|---|---|---|
| Brand | STMicroelectronics | STMicroelectronics | STMicroelectronics | STMicroelectronics | STMicroelectronics |
| Package | 64-LQFP (10x10 mm) | 64-LQFP (10x10 mm) - same | 64-LQFP (10x10 mm) - same | 64-LQFP (10x10 mm) - same | 64-LQFP (10x10 mm) - same |
| Operating Voltage (VBAT) | 6 V to 18 V (40 V load-dump) | 6 V to 18 V (40 V load-dump) | 6 V to 18 V (40 V load-dump) | 6 V to 18 V (40 V load-dump) | 6 V to 18 V (40 V load-dump) |
| Operating Temperature | -40 C to +95 C | -40 C to +95 C | -40 C to +95 C | -40 C to +95 C | -40 C to +95 C |
| Satellite Sensor Channels | 4 (analog/PSI5) | 4 (analog/PSI5) | 4 (analog/PSI5) | 4 (analog/PSI5) | 4 (analog/PSI5) |
| Battery Cut-off Switch | Yes | Yes | No | Yes | Yes |
| Integrated 5 V Regulator | External pass transistor | External pass transistor | External pass transistor | External pass transistor | External pass transistor |
| PSI5 Remote Sensor Interface | Yes | Yes | Yes | Yes | Yes (optimized) |
| Unit Price (qty 1, as of 2026-10-08) | USD 7.85 | USD 8.10 | USD 7.45 | USD 7.65 | USD 8.50 |
| Primary Differentiation | Standard feature set with battery cut-off support | Enhanced battery cut-off diagnostics | Standard feature set without cut-off | Standard + cut-off | PSI5-optimized variant |
أبرز الفروقات
- Battery cut-off switch integrated (no external MOSFET array required) (مقابلL9678TR (standard, no cut-off))
- Optimized PSI5 remote sensor interface path (مقابلL9678PTR (general-purpose PSI5 support))
- Lower unit cost in volume production (مقابلL9678PTR-S)
- Dual VDDQ pins for true 5 V/3.3 V mixed-voltage I/O support (مقابلCross-brand airbag SBIs (e.g., NXP FS65 with single-rail I/O))
ملاحظات التصميم
Size the energy reserve capacitor per ST's application note for the target deployment time. For 100 ms deployment after battery disconnect, a 470 µF to 1000 µF electrolytic (low-ESR, 25 V rating minimum) is typical. Place the capacitor within 5 cm of the ER_CAP pin to minimize parasitic inductance. The integrated charger limits inrush current to protect the battery feed during cold-crank when VBAT drops below 6 V.
The 64-LQFP (10x10 mm) package has a typical theta_JA of 35 C/W on a 4-layer JEDEC PCB. At maximum dissipation (estimated: 5 V regulator at 500 mA plus cut-off switch at 2 A = 2.5 W + 4 W = 12.5 W worst case), junction temperature rise would be approximately 437 C - well above limits. In airbag ECUs, average dissipation is typically under 1 W during standby, but designers must verify thermal performance with the actual copper-pour footprint on the LQFP thermal pad.
Place VBAT decoupling capacitors (typically 100 nF ceramic + 10 µF electrolytic) within 2 mm of the VBAT pins (1, 2). Route VBAT traces with at least 0.5 mm width for 2 A peak cut-off current. Connect the exposed thermal pad (pin 64) to a contiguous ground pour with at least 100 thermal vias to the inner ground plane. The PSI5 traces should be routed as a 100 Ω differential pair with ground shielding for EMI immunity in the vehicle harness environment.
Do NOT bond both VDDQ pins to the same voltage - this defeats the level-shifter isolation between 5 V and 3.3 V I/O domains. The VDDQ_5V pin powers 5 V-tolerant I/O (SPI, GPIO) while VDDQ_3V3 powers 3.3 V I/O. Mistakenly tying both to 3.3 V can damage the 5 V-tolerant pins. Also, do not omit the external pass transistors on the 5 V and 7.2 V regulators - they are mandatory and selected per the regulator load current.
The SPI bus between L9678PTR and SPC560Px MCU should be routed with ground-referenced traces, length-matched within 5 mm, and terminated at the MCU end. Add 33 Ω series resistors near the L9678PTR SPI pins for ringing suppression. The watchdog (WDO) signal must be a dedicated trace, not bundled with SPI, to prevent false watchdog triggers from SPI crosstalk in noisy automotive environments.
