L9678PTR - Automotive Airbag System Basis IC | STMicroelectronics
N.º de pieza: L9678PTR ✓ Activo| Cant. | Precio unitario | Total |
|---|---|---|
| 1 | $7.85 | $7,85 |
| 10 | $7.21 | $72,10 |
| 100 | $6.48 | $648,00 |
| 500 | $5.82 | $2.910,00 |
| 1.000 | $5.19 | $5.190,00 |
L9678PTR Descripción general
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.
Alternativas directas para L9678PTR — mismo encapsulado, compatible pin a pin. Se excluyen las piezas de otro encapsulado que requieren retrabajo de la PCB.
Variantes de esta serie
Modelos de la misma serie compatibles directamente con L9678PTR (mismo factor de forma y huella) — difiere en Package, Product Type, AEC-Q100 Qualification, Operating Temperature, Watchdog.
Herramienta de comparación rápida — seleccione piezas alternativas para compararlas lado a lado:
L9678PTR-S
✅ Sustitución directa✓ En stock
$3.5 / unidad
Ver hoja de datos →L9678TR
✅ Sustitución directa✓ En stock
$3.51 / unidad
Ver hoja de datos →L9678TR-S
✅ Sustitución directa📋 Alternativa de referencia (no en el catálogo)
L9678P-S
✅ Sustitución directa📋 Alternativa de referencia (no en el catálogo)
L9678PTR Valores máximos y características eléctricas
| Product Type | Automotive Airbag System Basis IC (SBI) |
| Encapsulado | 64-LQFP (10x10 mm) |
| Operating Voltage (VBAT) | 6 V to 18 V (load-dump tolerant up to 40 V) |
| Rango de temperatura de funcionamiento | -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 |
| Tipo de montaje | Surface Mount |
| Nivel MSL | 3 (168 hours) |
| Estado RoHS | Compliant |
Configuración de pines de L9678PTR
| Pin 1 | VBAT — Battery supply input (6-18 V) |
| Pin 2 | VBAT — Battery supply input (6-18 V) |
| Pin 3 | GND — Ground |
| Pin 4 | VCC5V — 5 V linear regulator output (external pass) |
| Pin 5 | VCC3V3 — 3.3 V integrated linear regulator output |
| Pin 6 | VDDQ_5V — 5 V I/O supply pin |
| Pin 7 | VDDQ_3V3 — 3.3 V I/O supply pin |
| Pin 8 | SAT1 — Satellite sensor interface channel 1 |
| Pin 9 | SAT2 — Satellite sensor interface channel 2 |
| Pin 10 | SAT3 — Satellite sensor interface channel 3 |
| Pin 11 | SAT4 — Satellite sensor interface channel 4 |
| Pin 12 | PSI5_TX — PSI5 Manchester transmit output |
| Pin 13 | PSI5_RX — PSI5 Manchester receive input |
| Pin 14 | VREG_7V2 — 7.2 V regulator for PSI5 sensor supply (external pass) |
| Pin 15 | ER_CAP — Energy reserve capacitor connection |
| Pin 16 | ER_CHG — Energy reserve charge control |
| Pin 17 | CUTOFF — Battery cut-off switch control output |
| Pin 18 | SPI_CLK — SPI clock from MCU |
| Pin 19 | SPI_MOSI — SPI master-out slave-in data |
| Pin 20 | SPI_MISO — SPI master-in slave-out data |
| Pin 21 | SPI_CS — SPI chip select (active low) |
| Pin 22 | WDI — Watchdog input from MCU |
| Pin 23 | WDO — Watchdog output to MCU |
| Pin 24 | RESET — Reset output to MCU |
| Pin 25 | IRQ — Interrupt request to MCU |
| Pin 26 | FAULT — Fault indicator output |
| Pin 27 | TEST — Test mode enable |
| Pin 28 | NC — Not connected (per datasheet) |
| Pin 29 | NC — Not connected (per datasheet) |
| Pin 30 | NC — Not connected (per datasheet) |
| Pin 31 | NC — Not connected (per datasheet) |
| Pin 32 | GPIO_1 — General-purpose I/O 1 |
| Pin 33 | GPIO_2 — General-purpose I/O 2 |
| Pin 34 | GPIO_3 — General-purpose I/O 3 |
| Pin 35 | GPIO_4 — General-purpose I/O 4 |
| Pin 36 | GPIO_5 — General-purpose I/O 5 |
| Pin 37 | GPIO_6 — General-purpose I/O 6 |
| Pin 38 | GPIO_7 — General-purpose I/O 7 |
| Pin 39 | GPIO_8 — General-purpose I/O 8 |
| Pin 40 | VSENS_SAT1 — Satellite 1 voltage sense |
| Pin 41 | VSENS_SAT2 — Satellite 2 voltage sense |
| Pin 42 | VSENS_SAT3 — Satellite 3 voltage sense |
| Pin 43 | VSENS_SAT4 — Satellite 4 voltage sense |
| Pin 44 | ISENS_SAT1 — Satellite 1 current sense |
| Pin 45 | ISENS_SAT2 — Satellite 2 current sense |
| Pin 46 | ISENS_SAT3 — Satellite 3 current sense |
| Pin 47 | ISENS_SAT4 — Satellite 4 current sense |
| Pin 48 | THERMAL — Thermal monitoring output |
| Pin 49 | TEMP_SENSE — On-die temperature sense |
| Pin 50 | GND — Ground |
| Pin 51 | GND — Ground |
| Pin 52 | GND — Ground |
| Pin 53 | GND — Ground |
| Pin 54 | VBAT_SENSE — Battery voltage sense for diagnostics |
| Pin 55 | V5V_SENSE — 5 V rail voltage sense |
| Pin 56 | V3V3_SENSE — 3.3 V rail voltage sense |
| Pin 57 | ER_SENSE — Energy reserve voltage sense |
| Pin 58 | PSI5_PULLUP — PSI5 bus pull-up connection |
| Pin 59 | PSI5_PULLDOWN — PSI5 bus pull-down connection |
| Pin 60 | CUTOFF_FB — Battery cut-off switch feedback |
| Pin 61 | ER_GATE — Energy reserve charge gate driver |
| Pin 62 | PROG — Programming/trim pin (factory use) / per datasheet NC in field |
| Pin 63 | NC — Not connected (per datasheet) |
| Pin 64 | EP — Exposed thermal pad - connect to GND |
Aplicaciones típicas
L9678PTR es adecuado para 6 aplicacións: 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.
Recomendado
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.
Recomendado
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.
Recomendado
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.
Recomendado
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.
Recomendado
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.
Recomendado
Resumen de productos recomendados
Datos de referencia de ingeniería para L9678PTR — comparación, orientación de diseño e información de cumplimiento.
Guía de selección
Comparación con alternativas
| Parámetro | Este producto | 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 |
Diferenciadores clave
- Battery cut-off switch integrated (no external MOSFET array required) (frente a L9678TR (standard, no cut-off))
- Optimized PSI5 remote sensor interface path (frente a L9678PTR (general-purpose PSI5 support))
- Lower unit cost in volume production (frente a L9678PTR-S)
- Dual VDDQ pins for true 5 V/3.3 V mixed-voltage I/O support (frente a Cross-brand airbag SBIs (e.g., NXP FS65 with single-rail I/O))
Notas de diseño
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.
