L9678PTR - Automotive Airbag System Basis IC | STMicroelectronics
Référence : L9678PTR ✓ Actif| Qté | Prix unitaire | 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 Présentation
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.
Alternatives de remplacement direct pour L9678PTR — même boîtier, compatible broche à broche. Les références à boîtier différent nécessitant une retouche du PCB sont exclues.
Variantes de cette série
Modèles de la même série directement compatibles avec L9678PTR (même facteur de forme et même empreinte) — différant par Package, Product Type, AEC-Q100 Qualification, Operating Temperature, Watchdog.
Outil de comparaison rapide — sélectionnez des références alternatives pour une comparaison côte à côte :
L9678PTR-S
✅ Remplacement direct✓ En stock
$3.5 / unité
Voir la fiche technique →L9678TR
✅ Remplacement direct✓ En stock
$3.51 / unité
Voir la fiche technique →L9678TR-S
✅ Remplacement direct📋 Alternative de référence (hors catalogue)
L9678P-S
✅ Remplacement direct📋 Alternative de référence (hors catalogue)
L9678PTR Valeurs maximales et caractéristiques électriques
| Product Type | Automotive Airbag System Basis IC (SBI) |
| Boîtier | 64-LQFP (10x10 mm) |
| Operating Voltage (VBAT) | 6 V to 18 V (load-dump tolerant up to 40 V) |
| Plage de température de fonctionnement | -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 |
| Type de montage | Surface Mount |
| Niveau MSL | 3 (168 hours) |
| Statut RoHS | Compliant |
Configuration des broches de L9678PTR
| Broche 1 | VBAT — Battery supply input (6-18 V) |
| Broche 2 | VBAT — Battery supply input (6-18 V) |
| Broche 3 | GND — Ground |
| Broche 4 | VCC5V — 5 V linear regulator output (external pass) |
| Broche 5 | VCC3V3 — 3.3 V integrated linear regulator output |
| Broche 6 | VDDQ_5V — 5 V I/O supply pin |
| Broche 7 | VDDQ_3V3 — 3.3 V I/O supply pin |
| Broche 8 | SAT1 — Satellite sensor interface channel 1 |
| Broche 9 | SAT2 — Satellite sensor interface channel 2 |
| Broche 10 | SAT3 — Satellite sensor interface channel 3 |
| Broche 11 | SAT4 — Satellite sensor interface channel 4 |
| Broche 12 | PSI5_TX — PSI5 Manchester transmit output |
| Broche 13 | PSI5_RX — PSI5 Manchester receive input |
| Broche 14 | VREG_7V2 — 7.2 V regulator for PSI5 sensor supply (external pass) |
| Broche 15 | ER_CAP — Energy reserve capacitor connection |
| Broche 16 | ER_CHG — Energy reserve charge control |
| Broche 17 | CUTOFF — Battery cut-off switch control output |
| Broche 18 | SPI_CLK — SPI clock from MCU |
| Broche 19 | SPI_MOSI — SPI master-out slave-in data |
| Broche 20 | SPI_MISO — SPI master-in slave-out data |
| Broche 21 | SPI_CS — SPI chip select (active low) |
| Broche 22 | WDI — Watchdog input from MCU |
| Broche 23 | WDO — Watchdog output to MCU |
| Broche 24 | RESET — Reset output to MCU |
| Broche 25 | IRQ — Interrupt request to MCU |
| Broche 26 | FAULT — Fault indicator output |
| Broche 27 | TEST — Test mode enable |
| Broche 28 | NC — Not connected (per datasheet) |
| Broche 29 | NC — Not connected (per datasheet) |
| Broche 30 | NC — Not connected (per datasheet) |
| Broche 31 | NC — Not connected (per datasheet) |
| Broche 32 | GPIO_1 — General-purpose I/O 1 |
| Broche 33 | GPIO_2 — General-purpose I/O 2 |
| Broche 34 | GPIO_3 — General-purpose I/O 3 |
| Broche 35 | GPIO_4 — General-purpose I/O 4 |
| Broche 36 | GPIO_5 — General-purpose I/O 5 |
| Broche 37 | GPIO_6 — General-purpose I/O 6 |
| Broche 38 | GPIO_7 — General-purpose I/O 7 |
| Broche 39 | GPIO_8 — General-purpose I/O 8 |
| Broche 40 | VSENS_SAT1 — Satellite 1 voltage sense |
| Broche 41 | VSENS_SAT2 — Satellite 2 voltage sense |
| Broche 42 | VSENS_SAT3 — Satellite 3 voltage sense |
| Broche 43 | VSENS_SAT4 — Satellite 4 voltage sense |
| Broche 44 | ISENS_SAT1 — Satellite 1 current sense |
| Broche 45 | ISENS_SAT2 — Satellite 2 current sense |
| Broche 46 | ISENS_SAT3 — Satellite 3 current sense |
| Broche 47 | ISENS_SAT4 — Satellite 4 current sense |
| Broche 48 | THERMAL — Thermal monitoring output |
| Broche 49 | TEMP_SENSE — On-die temperature sense |
| Broche 50 | GND — Ground |
| Broche 51 | GND — Ground |
| Broche 52 | GND — Ground |
| Broche 53 | GND — Ground |
| Broche 54 | VBAT_SENSE — Battery voltage sense for diagnostics |
| Broche 55 | V5V_SENSE — 5 V rail voltage sense |
| Broche 56 | V3V3_SENSE — 3.3 V rail voltage sense |
| Broche 57 | ER_SENSE — Energy reserve voltage sense |
| Broche 58 | PSI5_PULLUP — PSI5 bus pull-up connection |
| Broche 59 | PSI5_PULLDOWN — PSI5 bus pull-down connection |
| Broche 60 | CUTOFF_FB — Battery cut-off switch feedback |
| Broche 61 | ER_GATE — Energy reserve charge gate driver |
| Broche 62 | PROG — Programming/trim pin (factory use) / per datasheet NC in field |
| Broche 63 | NC — Not connected (per datasheet) |
| Broche 64 | EP — Exposed thermal pad - connect to GND |
Applications typiques
L9678PTR convient pour 6 applications: 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.
Recommandé
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.
Recommandé
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.
Recommandé
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.
Recommandé
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.
Recommandé
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.
Recommandé
Récapitulatif des produits recommandés
Données de référence d'ingénierie pour L9678PTR — comparaison, recommandations de conception et informations de conformité.
Guide de sélection
Comparaison avec les alternatives
| Paramètre | Ce produit | 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 |
Principaux différenciateurs
- Battery cut-off switch integrated (no external MOSFET array required) (vs L9678TR (standard, no cut-off))
- Optimized PSI5 remote sensor interface path (vs L9678PTR (general-purpose PSI5 support))
- Lower unit cost in volume production (vs L9678PTR-S)
- Dual VDDQ pins for true 5 V/3.3 V mixed-voltage I/O support (vs Cross-brand airbag SBIs (e.g., NXP FS65 with single-rail I/O))
Notes de conception
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.
