STMicroelectronics L9678PTR

Overview

L9678PTR from STMicroelectronics is an AEC-Q100 qualified automotive IC for airbag system control and battery cut-off management. It integrates energy reserve boost (23 V or 33 V ±5%), dual linear supplies (5.0 V/7.2 V ±4%), a fully integrated 3.3 V ±4% regulator, 4-channel squib/pyroswitch drivers (1.2 A @ 2 ms), and ISO9141 transceiver - deployed in low-end airbag control units requiring functional safety and pyro-fuse coordination.

For engineers reviewing the L9678PTR datasheet, L9678PTR pinout, L9678PTR application, or L9678PTR equivalent, this page delivers verified technical context, validated pin functions, confirmed deployment timing profiles, real-world diagnostic coverage (Rmeasure, STB, STG, leakage), and precise safing logic configurability - all critical for ASIL-B–aligned airbag ECU design and battery isolation systems.

Technical Context

The L9678PTR implements a multi-rail power architecture: high-frequency (1.882 MHz) ERBOOST regulator feeds energy reserve capacitors; user-configurable VDD5/VDD7.2 linear supplies use external pass transistors; and a fully integrated VDD3V3 regulator powers internal logic. All regulators include ±4% output tolerance and thermal/overcurrent protection.

Its deployment subsystem features four independent HSD/LSD drivers with programmable current profiles (1.2 A @ 2 ms, 1.75 A @ 0.5/0.7 ms), integrated safing FET (20 V/25 V nominal), and comprehensive diagnostics including R_measure, STB/STG monitoring, leakage detection, and FET functional tests - enabling deterministic squib firing under ISO 26262-compliant fault handling.

Key Specifications

Pinout & Package

LQFP64 (10 × 10 × 1.4 mm) package with exposed thermal pad; RoHS-compliant, AEC-Q100 qualified for automotive under-hood operation.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar airbag and pyro-switch control applications.

Compared with MC33816 and RAA278810, the L9678PTR uniquely combines energy reserve boost, dual external linear supplies, integrated 3.3 V LDO, and four-channel squib drivers in one AEC-Q100 package - reducing component count by ≥7 and eliminating external current-sense and boost-stage design effort.

Availability

L9678PTR is available at Aetrix Electronics and suitable for low-end airbag systems, battery cut-off modules, and pyro-fuse management systems requiring stable component supply, long-term automotive lifecycle support, and AEC-Q100 qualification.

Supply support for L9678PTR 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 management, and embedded processing solutions, with broad AEC-Q100 product portfolio and ISO/TS 16949-certified manufacturing.

The L9678PTR belongs to ST's automotive safety IC family, designed specifically for ASIL-B–compliant airbag control units and battery isolation systems - emphasizing integrated diagnostics, functional safety, and reduced system-level BOM cost.

FAQ

What is the maximum deployment voltage supported by the L9678PTR squib drivers?

The L9678PTR supports up to 25 V nominal deployment voltage via its integrated safing FET, with absolute maximum rating of 25 V on the VSF rail. The ERBOOST regulator provides selectable 23 V or 33 V ±5% energy reserve voltage - the latter used to charge external capacitors that feed the squib drivers during main battery loss.

Does the L9678PTR support both high-side and low-side squib configurations?

Yes - each of the four DEP1–DEP4 channels operates as configurable high-side or low-side drivers (HSD/LSD) with independent current monitoring and STB/STG diagnostics. Configuration is set via SPI registers DCR_x and SAF_ALGO_CONF, enabling flexible wiring for diverse squib topologies including dual-point grounding.

How does the L9678PTR handle energy reserve capacitor charging during sleep mode?

The L9678PTR maintains ERBOOST operation in Sleep mode, continuously charging the external energy reserve capacitor to maintain 23 V or 33 V. The ER charge circuit uses a dedicated current-limited path with automatic recharge after partial discharge - ensuring >95% energy retention for <100 ms wake-up-to-deployment latency.

Is the PSI-5 interface available on the L9678PTR part number?

No - the two-channel PSI-5 remote sensor interface is exclusive to the L9678P-S variant. The L9678PTR corresponds to the base L9678P version and omits PSI5A/PSI5B pins; it retains four-channel hall/resistive/switch sensor inputs and ISO9141 transceiver for diagnostics and communication.