STMicroelectronics L9951TR

Overview

L9951TR from STMicroelectronics is an automotive-grade, SPI-controlled rear door actuator driver IC integrating three half-bridge outputs (OUT1–OUT3) and two high-side drivers (OUT4–OUT5) for driving DC motors and resistive loads in vehicle door modules. It delivers 7.4 A peak through OUT1 (R_ON = 150 mΩ), 5 A through OUT2/OUT3 (R_ON = 200 mΩ), and 1.25 A through OUT4/OUT5 (R_ON = 800 mΩ), with integrated open-load, overload, overtemperature, and short-circuit diagnostics - deployed in rear door lock and lighting control systems.

For engineers reviewing the L9951TR datasheet, L9951TR pinout, L9951TR application, or L9951TR equivalent, key selection considerations include its PowerSO-36™ package, programmable softstart for inrush current management, 3 µA standby current (T_j ≤ 85°C), SPI-based diagnostic reporting, and reverse-polarity protection via external MOSFET driven by the CP pin.

Technical Context

The L9951TR implements a microcontroller-driven, multi-output power driver architecture with dedicated SPI interface (CSN, CLK, DI, DO) for real-time configuration and fault readback. Its five output channels are partitioned into three half-bridges (OUT1–OUT3) supporting bidirectional motor control and two high-side-only drivers (OUT4–OUT5) optimized for grounded resistive loads like incandescent bulbs.

All outputs feature independent protection: overcurrent detection with current monitor (CM/PWM pin), open-load and overload diagnostics, thermal shutdown at 170°C, and voltage monitoring (UV/OV on VS, POR on VCC). The integrated charge pump (CP pin) enables reverse-polarity protection using an external N-channel MOSFET, while programmable softstart mitigates inrush during motor startup.

Key Specifications

Pinout & Package

Package: PowerSO-36™ (exposed thermal pad, RoHS-compliant, thermally enhanced SO package).

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar rear door actuator driver applications.

Compared with VNQ5E050AKTR-E and BD1600FV-M, the L9951TR uniquely integrates motor + lighting drive, comprehensive diagnostics, and reverse-polarity support in one PowerSO-36™ package - reducing system-level complexity and enabling ASIL-B–compliant door module designs.

Availability

L9951TR is available at Aetrix Electronics and suitable for automotive rear door modules, body control units, and smart access systems requiring stable component supply, long-term lifecycle support, and AEC-Q100 qualified performance.

Supply support for L9951TR 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 broad portfolio coverage and AEC-Q100 qualification expertise.

The L9951TR belongs to ST's automotive power driver product line, designed specifically for intelligent body electronics - emphasizing integrated protection, SPI configurability, and ultra-low standby power for next-generation door and seat control modules.

FAQ

What is the maximum junction temperature and thermal shutdown behavior of the L9951TR?

The L9951TR operates from –40°C to +150°C junction temperature. Thermal shutdown activates at 170°C (rising) and releases at 150°C (falling), providing 20°C hysteresis. A separate temperature warning flag triggers at 150°C (rising) and clears at 130°C (falling), enabling early thermal mitigation via host MCU before shutdown.

How does the programmable softstart function work, and which outputs support it?

The softstart function is configurable per output via SPI register bits and applies to all five outputs (OUT1–OUT5). It controls the gate-drive ramp rate during turn-on to limit inrush current - critical for high-inductance motors or cold-filament bulbs. Ramp duration and slew rate are set by internal timers and are independent of load type.

Can the L9951TR drive inductive loads without external flyback diodes?

Yes. OUT1–OUT3 integrate internal bulk-drain diodes (high-side to VS, low-side to GND) for freewheeling. OUT4/OUT5 lack low-side diodes but include high-side-to-VS diodes; external diodes are recommended for highly inductive resistive loads. Layout best practices (short traces, local ceramic decoupling) remain essential for EMI control.

Is the L9951TR pin-compatible with the L9951XPTR variant?

No. The L9951TR uses PowerSO-36™ packaging, while L9951XPTR uses PowerSSO-36™ - differing in thermal pad structure, lead pitch, and mounting footprint. Though electrically identical, they are not mechanically interchangeable; PCB layout and thermal design must match the specific package variant selected.