STMicroelectronics L9678PTR-S

Overview

L9678PTR-S from STMicroelectronics is an AEC-Q100 qualified automotive IC for airbag system control and battery cut-off management. It integrates a 1.882 MHz boost regulator (23 V or 33 V ±5%), dual linear regulators (5.0 V/7.2 V ±4% and 3.3 V ±4%), four-channel squib/pyroswitch drivers (1.2 A @ 2 ms, 1.75 A @ 0.5/0.7 ms), two-channel PSI-5 remote sensor interface, and ISO9141 transceiver - deployed in low-end airbag control units requiring functional safety and pyro fuse coordination.

For engineers reviewing the L9678PTR-S datasheet, L9678PTR-S pinout, L9678PTR-S application, or L9678PTR-S equivalent, key selection considerations include its user-configurable safing logic, ERBOOST voltage selection, PSI-5 support (L9678P-S variant only), crossover switch performance (≤3 Ω), and integrated ADC-based system voltage diagnostics.

Technical Context

This IC implements a multi-rail power architecture with three independent linear regulators (VDD5, VDD3V3, VSF), a high-frequency boost converter for energy reserve (ERBOOST), and configurable deployment drivers supporting both high-side and low-side squib activation. Its safing engine executes user-defined logic across up to four deployment loops using SPI-configurable thresholds and arming pulse stretch.

The device embeds dual oscillators (7.5/16 MHz), a watchdog timer with retry capability, temperature sensing, and comprehensive diagnostics including R_measure, STB/STG leakage detection, FET tests, and short/open fault coverage for squibs, PSI-5 lines, and DC sensors - all operating within -40 °C to +95 °C.

Key Specifications

Pinout & Package

LQFP64 (10 × 10 × 1.4 mm) package with exposed thermal pad; 0.5 mm pitch, JEDEC standard footprint compatible with automated SMT assembly.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar airbag and pyro management applications.

Compared with MC33771B and RAA271000, the L9678PTR-S uniquely combines PSI-5 sensor interfacing, field-programmable safing logic, and dual-mode ERBOOST output - enabling flexible, scalable airbag system design without external interface or configuration ICs.

Availability

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

Supply support for L9678PTR-S 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 headquartered in Geneva, Switzerland, specializing in automotive, industrial, and power management ICs with strong functional safety expertise.

The L9678PTR-S belongs to ST's automotive safety ASSPs product line, designed specifically for airbag control units and pyro-based safety systems requiring ASIL-B compliance, diagnostic coverage, and field-upgradable safing logic.

FAQ

What is the purpose of the ERBOOST pin and how is its output voltage selected?

The ERBOOST pin delivers the regulated output of the internal high-frequency boost converter used to charge the energy reserve capacitor for squib deployment. Its voltage is selected via SPI register configuration (SYS_CFG[1:0]) to either 23 V or 33 V ±5%, enabling optimization for different squib resistance and deployment timing requirements without hardware changes.

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

Yes - it integrates four fully independent HSD/LSD deployment drivers, each configurable via SPI registers (DCR_x) for high-side, low-side, or complementary operation. Each channel supports 1.2 A @ 2 ms or 1.75 A @ 0.5/0.7 ms profiles and includes dedicated current monitoring and fault reporting.

How does the PSI-5 interface differ between L9678P and L9678P-S variants?

Only the L9678P-S (and thus L9678PTR-S) includes two-channel asynchronous PSI-5 interface. The base L9678P omits this feature entirely. PSI-5A/PSI-5B pins are functional only on the -S version and support standard PSI-5 protocol framing, CRC, and sensor power delivery per ISO 17987-5.

What diagnostic capabilities does the integrated ADC provide?

The 10-bit ADC monitors up to 12 analog inputs including VBAT, VDD5, VDD3V3, ERBOOST, COVRACT voltage, and sensor interface lines. It supports programmable sampling rates and triggers diagnostic interrupts upon out-of-range readings, enabling real-time system health assessment per ISO 26262 ASIL-B requirements.