STMicroelectronics L9904

Overview

L9904 from STMicroelectronics is an automotive H-bridge motor bridge controller IC with ISO 9141 bus interface, designed to drive four external N-channel MOSFETs in dual half-bridge configuration. It operates from 8V–28V supply (down to 6V with integrated step-up converter), features real-time diagnostic output (DG), programmable cross-conduction protection (PR pin), and integrated charge pump (CP) for reverse battery protection. Used in automotive seat/mirror/window actuator control systems.

For engineers reviewing the L9904 datasheet, L9904 pinout, L9904 application, or L9904 equivalent, key selection considerations include its ISO 9141 K-line compatibility, dual high-side/low-side gate driver timing (tGH1LH ≤ 1.3 µs with cross-conduction protection), bootstrap capacitor support (CB1/CB2), thermal/overvoltage/short-circuit protection thresholds, and 30 kHz PWM capability.

Technical Context

The L9904 implements a dual half-bridge control architecture with independent gate drivers (GH1/GL1 and GH2/GL2), each supporting bootstrap operation via external capacitors CB1 and CB2. Its ISO 9141 interface uses open-drain K-line (pin 9) with internal pull-up and short-circuit detection (tSH = 10–40 µs), plus TX/RX pins for microcontroller communication.

Protection logic includes thermal shutdown at TJ ≥ 150°C (hysteresis 15°C), overvoltage disable at VVS ≥ 33 V (hysteresis 1.6 V), undervoltage disable at VVS ≤ 7 V (hysteresis 0.66 V), and per-bridge short-circuit detection (VS1TH/VS2TH = 4 V, tSCd = 5–15 µs). The PR pin sets cross-conduction delay (tCCP = 0.69·RPR·CPR) using external RC network.

Key Specifications

Pinout & Package

Package: SO20 (Small Outline, 20-pin, 12.6 × 7.5 mm, 1.27 mm pitch), compliant with JEDEC MS-013AC, moisture sensitivity level 3.

Key Features

Applications

Equivalent & Alternatives

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

Compared with BD3539FV and VNQ5E050AK, the L9904 uniquely integrates ISO 9141 bus interface, dual half-bridge gate drivers with bootstrap support, and real-time multi-fault diagnostics - making it purpose-built for automotive body electronics requiring ECU interoperability and functional safety awareness.

Availability

L9904 is available at Aetrix Electronics and suitable for automotive power seat control, power window lift modules, auto-dimming mirror actuation, and convertible top actuation systems requiring stable component supply across extended temperature and voltage ranges.

Supply support for L9904 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 broad AEC-Q100 qualification coverage.

The L9904 belongs to ST's automotive motor driver product line, engineered specifically for body electronics applications requiring ISO 9141 diagnostics, reverse battery protection, and robust H-bridge control in harsh vehicle environments.

FAQ

What is the minimum supply voltage supported by L9904 with the ST pin enabled?

The L9904 supports operation down to 6 V when the ST pin drives an external step-up converter (inductor + diode). Below 8 V, the internal oscillator activates ST at ~100 kHz to boost VS; regulation disables above 10 V to prevent EMI. This enables reliable cold-cranking performance in 12 V automotive systems.

How does the L9904 implement short-circuit protection on S1 and S2 pins?

The L9904 continuously monitors S1 and S2 voltages against VS1TH/VS2TH = 4 V thresholds. If Sx remains ≤ 4 V for tSCd = 5–15 µs (indicating short-to-ground) or ≥ 0.55·VVS (short-to-battery), the corresponding high-side or low-side driver is disabled. DG asserts LOW, and recovery requires DIR or PWM state change.

Can the L9904 drive standard-level MOSFETs without external level shifters?

Yes. The GH1/GH2 drivers deliver VGHxH = VVS + 6.5–14 V (ensuring ≥ 10 V gate-source voltage at 13.5 V battery), and GL1/GL2 provide VGLxH = 7–14 V. With proper bootstrap capacitor sizing (≥ 0.1 µF) and gate resistors, standard 10 V-threshold N-MOSFETs operate reliably without external level-shifting circuitry.

Is the ISO 9141 interface on L9904 compatible with both K-line and L-line protocols?

The L9904 implements only K-line functionality (pin 9) per ISO 9141-2, including open-drain TX/RX, voltage thresholds (VKL = 0.45·VVS, VKH = 0.55·VVS), and short-circuit recovery timing. It does not support L-line (timing line) or ISO 14230-4 (KWP2000) higher-layer protocols - those require external microcontroller firmware handling.