STMicroelectronics L9925

Overview

L9925 from STMicroelectronics is a dual full-bridge DMOS motor driver IC designed for bipolar stepper motor control and bidirectional DC inductive loads. It integrates two independent H-bridges with R_DS(on) < 0.75 Ω @ 25°C, 14 V; supports 0.8 A continuous DC output per channel without heatsink; features integrated charge pump, thermal shutdown at 150°C, and CMOS-compatible 5 V logic inputs. Used in automotive seat/mirror actuators and industrial positioning systems.

For engineers reviewing the L9925 datasheet, L9925 pinout, L9925 application, or L9925 equivalent, this page delivers verified electrical parameters, SO28 package mapping, bridge-level enable/input logic behavior, thermal protection thresholds, and real-world stepper motor drive configurations - all derived from ST's official 1999 datasheet (Doc ID D88AT424/D99AT423).

Technical Context

The L9925 implements two fully independent full-bridge outputs using BCD (Bipolar-CMOS-DMOS) process technology, integrating power DMOS transistors, Schmitt-trigger inputs, and an on-chip charge pump to sustain gate drive across 6–40 V supply range. Each bridge accepts non-inverting digital inputs (IN1–IN4) and separate active-high enables (EN1/EN2), enabling four-quadrant control modes including two-phase, one-phase, and enable chopping.

Thermal protection disables both bridges when junction temperature reaches 150°C (hysteresis = 25°C); cross-conduction prevention is enforced by internal gate-source voltage monitoring. Output short-circuit protection and ESD robustness (>2 kV) are built-in, and quiescent current drops below 200 µA when both EN pins are low.

Key Specifications

Pinout & Package

Package: SO28 (18.1 × 10.65 mm, 1.27 mm pitch), surface-mount, with exposed thermal pad (PGND pins serve as primary thermal conduction path).

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar dual H-bridge motor driver applications.

Compared with TB6612FNG and VNQ7050AJ, the L9925 uniquely combines dual full-bridge integration, 40 V operation, and self-contained charge pump - making it irreplaceable for legacy 24 V automotive body control modules where board area and supply flexibility are critical.

Availability

L9925 is available at Aetrix Electronics and suitable for automotive seat actuators, industrial stepper positioning systems, and medical infusion pump motor control requiring stable component supply across extended temperature and voltage ranges.

Supply support for L9925 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 vertical manufacturing and broad analog/mixed-signal IP.

The L9925 belongs to ST's legacy automotive power driver product line, engineered specifically for robust, low-pin-count motor actuation in harsh 12/24 V vehicle environments - prioritizing thermal resilience, ESD tolerance, and minimal external component count.

FAQ

Is the L9925 still in production, and what is its lifecycle status?

The L9925 is marked "Obsolete Product(s)" in ST's official documentation (1999 datasheet revision), indicating it is no longer actively manufactured. However, Aetrix Electronics maintains legacy inventory with full traceability and offers long-term supply assurance through authorized redistribution channels and controlled-batch sourcing - supporting repair, maintenance, and legacy system continuity.

Can the L9925 drive unipolar stepper motors?

No - the L9925 is designed exclusively for bipolar stepper motors and bidirectional DC inductive loads. Its dual full-bridge topology requires center-tapped or dual-winding motors; unipolar steppers rely on single-polarity current paths and require different driver architectures (e.g., ULN2003 arrays or dedicated unipolar ICs like L293D).

What is the maximum allowable PCB copper area for thermal dissipation?

Per ST's datasheet, total power dissipation reaches 2 W with 8 cm² of 2-oz copper on the PCB (T_amb = 70°C). The SO28 package relies on PGND pins (1, 7, 8, 14, 21, 22) for thermal conduction - optimal layout uses internal ground planes connected directly to these pins and a minimum 6 cm² copper pour under the IC body per ST's thermal data (R_{th j-pins} = 15 °C/W).

Does the L9925 support PWM speed control, and what frequency range is validated?

Yes - the L9925 supports PWM input on INx pins (not ENx) for variable-speed control. ST validates timing parameters (t_d-on, t_d-off, t_rise, t_fall) up to 50 µs delays and 20 µs edge times, enabling reliable operation at chopper frequencies ≤10 kHz. Higher frequencies risk incomplete switching transitions and increased dynamic losses due to fixed gate-drive strength.