STMicroelectronics L9781

Overview

L9781 from STMicroelectronics is an AEC-Q100 qualified automotive multi-valve pre-driver IC for diesel and gasoline direct injection systems. It controls up to five inductive loads via peak-and-hold current regulation, drives 11 external N-channel logic-level MOSFETs, integrates a DC/DC step-up controller (up to 80 V VTank), and provides hardware-based fault protection including short-circuit detection on all channels.

For engineers reviewing the L9781 datasheet, L9781 pinout, L9781 application, or L9781 equivalent, this device is selected for high-reliability fuel injector control where precise current profiling, integrated diagnostics, SPI-configurable thresholds, and dual-bank independent actuation are required in engine management units.

Technical Context

The L9781 implements three independent pre-driver controller blocks: one dedicated DC/DC converter controller (VTank generation), two full-featured bank controllers (Bank A and Bank B) each supporting high-side VTank/VBat and low-side MOSFET pre-driving, plus a separate fuel pump peak-and-hold controller. All banks use internal finite state machines (FSMs) for autonomous current control sequencing triggered only by command inputs.

Current sensing is performed via differential amplifiers with programmable gain per channel, and peak current thresholds are set via embedded 8-bit DACs. Hardware protection includes overcurrent detection, open-load monitoring, and thermal shutdown - all managed without MCU intervention via dedicated diagnosis logic blocks.

Key Specifications

Pinout & Package

L9781 is housed in a 10×10 mm LQFP64 package with exposed thermal pad, compliant with AEC-Q100 Grade 0 requirements and ECOPACK® environmental standards.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar multi-valve pre-driver applications.

Compared with TPIC46L01 and MC33816, the L9781 uniquely integrates VTank generation, dual independent injector banks, and a dedicated fuel pump controller - enabling full injector + pump drive in a single AEC-Q100-compliant IC with 8 MHz SPI for high-speed diagnostics.

Availability

L9781 is available at Aetrix Electronics and suitable for diesel common rail systems, gasoline direct injection ECUs, and fuel pump control modules requiring stable component supply across automotive production lifecycles.

Supply support for L9781 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 manufacturing scale and AEC-Q100 design expertise.

The L9781 belongs to ST's automotive power driver product line, engineered specifically for high-reliability, high-current valve actuation in modern internal combustion engine control units - emphasizing hardware autonomy, fault resilience, and SPI configurability.

FAQ

What is the maximum VTank voltage the L9781 can generate?

The L9781 DC/DC converter controller supports VTank generation up to 80 V, achieved using an external push-pull N-channel MOSFET stage and current-sensing feedback. The internal pre-driver (GLS_T, RSP_T, RSN_T) is rated for this voltage rail, and VT_FB input monitors VTank with hysteresis for stable regulation.

How does the L9781 handle injector short-circuit faults?

The L9781 uses dedicated hardware protection blocks per channel that detect overcurrent in real time using differential current sense amplifiers and programmable DAC thresholds. Upon detection, it immediately disables the affected pre-driver stage and asserts the open-drain IRQ pin - all without MCU intervention or software latency.

Can the L9781 drive both gasoline and diesel injectors simultaneously?

Yes - its dual-bank architecture (Bank A and Bank B) supports independent control of different injector types. For example, Bank A can drive high-impedance gasoline DI injectors with fast peak-and-hold profiles, while Bank B manages low-impedance diesel solenoid valves with longer hold durations, all configured via separate SPI registers and command pins.

Is an external clock required for L9781 operation?

No - the L9781 includes an internal oscillator for basic timing, but CLK_EXT (Pin 48) supports optional external clock injection (e.g., from ECU master clock) to synchronize actuation timing across multiple L9781 devices or align with engine crankshaft position signals for deterministic injection phasing.