STMicroelectronics L9680TR

Overview

L9680TR from STMicroelectronics is an AEC-Q100 qualified automotive airbag system IC integrating 12-channel squib/pyroswitch drivers, four PSI-5 remote sensor interfaces, three configurable GPOs, nine DC sensor inputs, dual boost (ERBOOST/SYNCBOOST) and triple buck (SATBUCK/VCC/VSF) regulators, energy reserve crossover switch (3 Ω, 912 mA), and 32-bit SPI interface - deployed in mid/high-end airbag control units for passenger and driver-side deployment with cut-off battery and pyro-fuse management.

For engineers reviewing the L9680TR datasheet, L9680TR pinout, L9680TR application, or L9680TR equivalent, this device requires precise validation of squib resistance measurement (Rmeasure), STB/STG diagnostics, PSI-5 timing compliance, safing logic configuration, and ER capacitor ESR diagnostics in safety-critical airbag ECU designs.

Technical Context

The L9680TR implements a multi-regulator power architecture: ERBOOST (23 V/33 V ±5%, 1.882 MHz) charges the energy reserve capacitor; SYNCBOOST (12 V/14.75 V) powers PSI-5 SYNC pulses; SATBUCK (7.2 V/9 V ±4%) supplies remote sensors; VCC buck (3.3 V/5.0 V ±3%) powers the MCU; and VSF regulates the safing switch. All switching regulators operate at fixed 1.882 MHz for EMI control and filter size reduction.

Its deployment subsystem features 12 independently controlled HSD/LSD drivers with current monitoring, Rmeasure, leakage (VRCM), STB/STG, and FET integrity tests. Safing logic is user-customizable via SPI-configurable thresholds, arming matrices, and temporal (WD1) and algorithmic (WD2) watchdogs - enabling deterministic, ASIL-B compliant arming decisions per ISO 26262.

Key Specifications

Pinout & Package

TQFP100 exposed pad down (14 mm × 14 mm × 1.0 mm), thermally enhanced for sustained 12-channel driver operation and regulator thermal dissipation.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar airbag system controller applications.

Compared with MC33816 and RAA278812, the L9680TR uniquely integrates ER capacitor diagnostics, PSI-5 native support, and configurable passenger inhibit logic - making it optimal for mid/high-end airbag ECUs requiring autonomous satellite sensor management and field-deployable energy reserve validation.

Availability

L9680TR is available at Aetrix Electronics and suitable for mid/high-end airbag systems, cut-off battery systems, and pyro-fuse/switch management requiring stable component supply, long-term automotive lifecycle support, and AEC-Q100 traceability.

Supply support for L9680TR includes scheduled delivery planning, volume procurement assistance, BOM continuity management, traceable sourcing, and lifecycle availability coordination for OEM customers, industrial embedded developers, connected-device designers, and electronics production programs.

Manufacturer

STMicroelectronics is a global semiconductor leader specializing in automotive, power, and embedded solutions, with decades of safety-critical IC development experience.

The L9680TR belongs to ST's automotive airbag system IC product line, engineered specifically for ASIL-B compliant, high-integration airbag ECUs that require consolidated power regulation, multi-sensor interfacing, and deterministic deployment control.

FAQ

What is the maximum continuous current rating of the integrated energy reserve crossover switch?

The L9680TR's integrated energy reserve crossover switch supports up to 912 mA continuous current with a typical R_DS(on) of 3 Ω. This rating is validated across the full −40 °C to +95 °C operating temperature range and includes thermal derating curves in Section 17.10 of the datasheet. Peak pulsed current capability exceeds 1.5 A for <100 µs durations during squib firing sequences.

Does the L9680TR support both PSI-5 and active wheel speed sensor protocols on the same interface pins?

Yes - the four remote sensor channels support either PSI-5 (differential, current-loop) or active wheel speed sensor (WSS) modes via SPI-configurable RSCRx registers. Each channel operates independently; PSI-5 uses constant-current sourcing with Manchester-encoded data, while WSS mode applies programmable bias and thresholds for variable-reluctance or Hall-effect signals. Mode selection is per-channel and non-overlapping.

How does the L9680TR perform squib resistance measurement (Rmeasure) without external components?

Rmeasure is executed using internal current sources and ADC paths: a precision 1 mA current is forced through the squib loop, and the resulting voltage drop is measured across dedicated sense nodes (STB/STG). The integrated 12-bit ADC digitizes the result, and the value is reported in DCMTSxy registers. Calibration coefficients are stored in OTP memory to correct for channel-to-channel gain/offset mismatches.

Can the safing logic be reconfigured in-field via SPI, and what safeguards prevent unauthorized changes?

Safing logic parameters - including thresholds, arming matrices, and comparison masks - are fully SPI-reconfigurable during ACTIVE mode. Unauthorized writes are prevented by a two-stage safeguard: (1) SAF_ENABLE register must be set to '1' before any SAF_CONTROL_x write, and (2) all safing record updates require matching seed/key challenge-response handshake via WD2_SEED/WD2_KEY registers - implemented in hardware with tamper-resistant OTP storage.