STMicroelectronics L9908TR

Overview

L9908TR from STMicroelectronics is an AEC-Q100 qualified, ISO 26262 ASIL-D compliant 3-phase gate driver unit for automotive brushless motor control. It integrates six N-channel FET pre-drivers (three half-bridges), three differential current monitors with SPI-configurable gain/offset, three real-time phase voltage feedback channels, and a 32-bit 10 MHz SPI interface with 5-bit CRC and frame counter. Designed for EPS, HVAC blowers, and engine cooling fans, it supports 4.5 V to 75 V VDH operation across 12 V, 24 V, and 48 V battery systems.

For engineers reviewing the L9908TR datasheet, L9908TR pinout, L9908TR application, or L9908TR equivalent, this device delivers verified high-voltage robustness (−14 V to 95 V on motor pins), independent 0–100% PWM control per gate, SPI-readable junction temperature and fault status, and integrated diagnostics including shoot-through, dead-time, open-load, short-to-rail, and over-temperature protection.

Technical Context

The L9908TR implements a fully configurable 3-phase gate driver architecture with independent high-side (GHS/SHS/CBS) and low-side (GLS/SLS) terminal sets per phase, enabling flexible motor control strategies including sinusoidal, trapezoidal, and field-oriented control. Its charge pump (CP1/CP2) and bootstrap circuitry support sustained high-side drive up to 75 V VDH while maintaining ≥7 V VPRE for reliable gate turn-on.

Current sensing uses an ADC/DAC architecture with SPI-adjustable gain (±10 mV/V to ±200 mV/V) and offset, delivering ground-referenced measurements with 0–4.6 V DAC output range and built-in error calibration. Phase voltage monitoring provides SPI-programmable feedback and duty-cycle measurement, synchronized via the same 32-bit SPI interface that includes window watchdog, frame counter, and CRC for functional safety compliance.

Key Specifications

Pinout & Package

TQFP48 package with exposed thermal pad (down-facing, non-electrical, recommended to connect to PCB GND plane for thermal management).

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar 3-phase automotive gate driver applications.

Compared with DRV3255-Q1 and MPQ6535-AEC1, the L9908TR uniquely combines 75 V VDH tolerance, on-die current monitor calibration, SPI-accessible phase voltage and junction temperature, and full ASIL-D diagnostic coverage - making it the only option qualified for high-voltage, safety-critical eBooster and next-gen 48 V EPS systems.

Availability

L9908TR is available at Aetrix Electronics and suitable for Electronic Power Steering (EPS), HVAC blower systems, and engine cooling fans requiring stable component supply across automotive production lifecycles.

Supply support for L9908TR 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 solutions, with deep expertise in functional safety and high-voltage analog/mixed-signal ICs.

The L9908TR belongs to ST's automotive gate driver product line, engineered specifically for ASIL-D–compliant 3-phase BLDC motor control in safety-critical vehicle subsystems such as steering, braking, and thermal management.

FAQ

What is the maximum allowable transient voltage on SHS pins?

The L9908TR supports −14 V to 95 V transient voltage on SHS pins (t ≤ 200 ns), validated per ISO 16750-2 and VDA 320 standards. This rating ensures immunity to inductive kickback during MOSFET turn-off and load dump events in 12 V/24 V/48 V systems without external clamping.

How does the L9908TR achieve ASIL-D compliance?

ASIL-D compliance is achieved through redundant internal monitoring (clock, supply, temperature), hardware-enforced diagnostics (shoot-through, dead-time, open-load), SPI-accessible status registers with CRC-protected reads, and certification evidence per ISO 26262 Part 5/6. No external safety controller is required for basic fault detection and reporting.

Can the current monitor gain be adjusted dynamically during motor operation?

Yes - the L9908TR's current monitor gain (±10 mV/V to ±200 mV/V) and offset are SPI-programmable in real time without interrupting motor control. This enables adaptive current scaling during startup, overload, or regenerative braking phases while maintaining measurement linearity.

What thermal management guidance applies to the exposed pad?

The exposed thermal pad must be soldered to a minimum 200 mm² copper pour connected to SGND/PGND with ≥4 thermal vias (0.3 mm diameter, 0.8 mm pitch). This achieves ≤35 °C/W junction-to-board thermal resistance, critical for sustained 75 V VDH operation at 125 °C ambient.