STMicroelectronics L9347LF

Overview

L9347LF from STMicroelectronics is an intelligent quad low-side power switch for automotive ABS and chassis control systems, integrating two 5A conventional switches (Ch1–Ch2) and two 2.5A current-regulated channels (Ch3–Ch4), with 0.2 Ω/0.35 Ω typical R_DS(on), integrated Zener clamping (Ch1–Ch2) and freewheeling diodes (Ch3–Ch4), and real-time status monitoring per channel.

For engineers reviewing the L9347LF datasheet, L9347LF pinout, L9347LF application, or L9347LF equivalent, this device supports precise inductive load control in safety-critical braking systems, offers diagnostic-ready status outputs, supports external 250 kHz clock synchronization, and enables drift detection between regulated channels for long-term valve performance validation.

Technical Context

The L9347LF implements dual-mode output architecture: Ch1–Ch2 use DMOS transistors with integrated Zener clamping (V_Z = 45–60 V) for fast inductive energy dissipation; Ch3–Ch4 employ digital PI regulation (K_P = 0.96, K_I = 0.126) synchronized to a 250 kHz external clock, achieving ±10% current accuracy across 250 mA–2.25 A range with 5 mA resolution.

Diagnostic logic includes independent push-pull status outputs per channel, short-circuit detection with 4–30 μs shutdown delay, selective overtemperature shutdown at 175–200 °C, open-load detection via V_QU = 0.33×V_Q, and recirculation error detection triggered at V_rerr = 45–60 V when D3/D4 are disconnected.

Key Specifications

Pinout & Package

Package: PowerSO-36 with integrated cooling area - thermally optimized for high-power automotive PCB mounting, R_thJC = 2 K/W, rated for T_j = −40 to +150 °C continuous operation.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar quad low-side switch applications.

Compared with L9347LF, VNS3NV04PTR-E lacks integrated regulation and diagnostics, increasing BOM count and system complexity; TLE7234SE provides analog current sensing but no digital regulation or drift detection, limiting long-term reliability assurance in safety-critical ABS applications.

Availability

L9347LF is available at Aetrix Electronics and suitable for automotive braking systems, chassis control modules, and electric power steering assist circuits requiring stable component supply, AEC-Q100 Grade 1 qualification, and long-lifecycle availability.

Supply support for L9347LF 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-grade power ICs, microcontrollers, and sensors, with manufacturing certified to IATF 16949 and AEC-Q100 standards.

The L9347LF belongs to ST's Intelligent Power Switch family, designed specifically for ISO 26262-compliant automotive body and chassis applications requiring integrated protection, diagnostics, and current regulation.

FAQ

What is the maximum continuous output current rating per channel?

L9347LF supports 5 A continuous current on Channels 1 and 2 (non-regulated), and 2.5 A on Channels 3 and 4 (current-regulated), with thermal derating above 125 °C junction temperature. Absolute maximum ratings allow transient 9 A overload on Ch1–Ch2 and 8 A on Ch3–Ch4 for ≤30 μs, limited by internal short-circuit protection.

How does the current regulation function work on Channels 3 and 4?

Channels 3 and 4 implement a digital PI regulator synchronized to the 250 kHz external clock. The input PWM duty cycle (10–90%) sets the target current; the regulator measures current during the freewheeling phase via an internal sense resistor and adjusts output PWM (3.9 kHz) to maintain ±10% accuracy across 250 mA–2.25 A, with 5 mA resolution and 10 ms regulation error timeout.

Can L9347LF operate without the external 250 kHz clock signal?

No - the external 250 kHz clock is mandatory for all regulated functions. Without it, Channels 3 and 4 disable regulation and default to open-drain switching; clock watchdog circuitry forces status inversion and output shutdown if f_CLK falls below 10 kHz or duty cycle deviates beyond 45–55%. Non-regulated channels (Ch1–Ch2) remain functional but lose synchronized diagnostics.

What diagnostic faults trigger status output inversion?

Status outputs invert on six confirmed faults: short-circuit (t_SCP = 4–30 μs), overtemperature (T_th = 175–200 °C), open load (V_QU = 0.33×V_Q), supply loss (V_Sloss = 2–4.5 V), recirculation error (V_rerr = 45–60 V), and clock failure (f_CLK,min = 10 kHz or DC outside 45–55%). Each fault is latched and held for ≥896 μs before automatic reset.