STMicroelectronics L9654TR

Overview

L9654TR from STMicroelectronics is a quad squib driver and dual satellite sensor interface ASIC designed for automotive airbag control units (ACUs). It delivers 1.2 A (min.) for ≥2 ms and 1.75 A (min.) for ≥1 ms under load-dump conditions, supports Manchester protocol decoding for two remote sensors, and integrates SPI-controlled diagnostics including squib resistance measurement, short-to-battery/ground detection, and MOSFET health monitoring.

For engineers reviewing the L9654TR datasheet, L9654TR pinout, L9654TR application, or L9654TR equivalent, this device serves as a safety-critical deployment controller requiring precise current delivery timing, fault-reporting integrity via 5.5 MHz SPI, dual-satellite protocol flexibility ("A" and variable-bit-rate "B"), and robust ESD protection (2 kV on all pins) in automotive crash-sensing systems.

Technical Context

The L9654TR implements four independent high-side/low-side MOSFET pairs for squib actuation, each with programmable current trip points, fault timers, and diagnostic modes accessible via dedicated SPI interfaces (CS_D, CS_S, CS_A). Its dual satellite interface decodes Manchester-encoded signals from remote acceleration sensors using configurable bit-rate detection and FIFO buffering.

Functional safety is enforced through independent continuity checks, open/short diagnostics per squib channel, loss-of-ground detection, and arming chain validation via daisy-chained SPI. All drivers operate across VRES input ranges from 6.9 V to 35 V, supporting deployment under cold-crank and load-dump transients while maintaining ±5% current accuracy.

Key Specifications

Pinout & Package

Package: 48-lead LQFP (7 mm × 7 mm, 0.5 mm pitch), RoHS-compliant, with exposed thermal pad for enhanced power dissipation in safety-critical mounting.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar squib driver and satellite interface applications.

Compared with MC33816 and RAA278812, the L9654TR uniquely combines analog resistance readout, dual Manchester protocol support, and 1.75 A load-dump resilience-making it optimal for legacy-compatible, high-integrity airbag ECUs where sensor interoperability and diagnostic redundancy are critical.

Availability

L9654TR is available at Aetrix Electronics and suitable for automotive airbag control units, rollover detection modules, and seatbelt pretensioner systems requiring stable component supply, long-term lifecycle assurance, and AEC-Q100 qualified performance.

Supply support for L9654TR 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, industrial, and power management ICs, with over 30 years of safety-critical system expertise.

The L9654TR belongs to ST's automotive safety ASIC product line, engineered specifically for airbag electronic control units requiring high-current squib actuation, multi-sensor interface flexibility, and comprehensive hardware-level diagnostics.

FAQ

What is the minimum VRES voltage required to achieve 1.2 A squib drive current?

The L9654TR guarantees 1.2 A (min.) squib current at VRES = 6.9 V, validated under load-dump conditions. This enables reliable deployment during cold-crank scenarios where battery voltage drops below 7 V. Operation below 6.9 V may result in reduced current compliance or automatic shutdown per internal undervoltage lockout.

How does the L9654TR handle Manchester protocol ambiguity between "A" and "B" satellite sensors?

The L9654TR automatically detects and adapts to both "A" (fixed 24-bit) and "B" (variable-length) Manchester protocols using on-chip bit-time measurement and frame synchronization logic. No register configuration is needed-the device identifies protocol type during initial message reception and locks to the detected format for subsequent frames.

Can the analog AOUT pin be used simultaneously with SPI-based resistance measurement?

Yes-AOUT provides continuous analog voltage proportional to measured squib resistance (0–2.5 V range), while SPI registers report the same value digitally with 10-bit resolution. Both outputs are updated concurrently during continuity diagnostic mode, allowing redundant verification or real-time analog monitoring without SPI bus contention.

What failure modes trigger automatic shutdown of a squib driver channel?

A squib driver channel shuts down immediately upon detection of short-to-battery, short-to-ground, open circuit, or loss-of-ground exceeding 1 Ω. Each channel has an independent fault timer; if continuity or resistance measurement fails to complete within the programmed timeout (configurable up to 100 ms), the driver disables and sets its respective fault flag in the SPI status register.