STMicroelectronics L9524C

Overview

L9524C from STMicroelectronics is a glow plug system control IC for diesel engine management, implementing quad high-side N-channel MOSFET gate drivers with PWM control, adjustable gate charge/discharge currents (270–540 µA), overcurrent monitoring with user-adjustable threshold (150–290 mV), and integrated battery/supply/junction temperature/charge pump voltage monitoring with shutdown. It supports up to six glow plugs via four external power switches or one relay in automotive cold-start systems.

For engineers reviewing the L9524C datasheet, L9524C pinout, L9524C application, or L9524C equivalent, key selection criteria include high-side gate drive capability, two-wire diagnostic interface compatibility, shunt- or transistor-based current sensing modes, power regulation under varying battery voltage (8–16 V), and AEC-Q100 qualified thermal shutdown at 125–150 °C.

Technical Context

The L9524C operates in six configurable modes: two relay-based (go/no-go or serial diagnostic) and four transistor-based (shunt/transistor sense × power regulation enabled/disabled). Its gate drivers support active clamping during load dump (V_VS ≥ 28 V), negative voltage clamping (−18 V), and precise timing control with channel gap (50–250 µs) and delay (2.5–5 ms).

It integrates dual supply monitoring (VS and BAT pins), where VS governs primary operation and BAT enables fail-safe shutdown and battery-voltage-dependent power regulation. The internal charge pump (0.6–7 MHz) generates boosted gate drive voltage, monitored independently with undervoltage lockout (V_CP < V_VS + 3.5 V).

Key Specifications

Pinout & Package

SO24 package: 24-pin small outline, 0.75 mm pitch, exposed thermal pad (not electrically connected), body size 15.4 × 7.5 mm, compliant with JEDEC MS-013AC.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar glow plug control applications.

Compared with TLE7209-2R and MC33816, the L9524C delivers fully autonomous glow plug control-including PWM timing, battery-voltage compensation, and dual-sensing mode selection-in a single SO24 package, reducing BOM count and software overhead in cost-sensitive diesel ECUs.

Availability

L9524C is available at Aetrix Electronics and suitable for diesel engine cold-start systems, commercial vehicle ECU production, and aftermarket glow plug module manufacturing requiring stable component supply across automotive temperature and lifetime requirements.

Supply support for L9524C 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-grade analog, power, and microcontroller solutions with broad AEC-Q100 qualification coverage.

The L9524C belongs to ST's Automotive Power Switch family, designed specifically for intelligent high-side control of resistive loads in diesel engine management-emphasizing functional safety, transient robustness, and minimal external component count.

FAQ

What is the purpose of the CP (charge pump) pin on the L9524C?

The CP pin outputs a boosted voltage (V_VS + 5 V to +18 V) generated by an internal charge pump to ensure sufficient gate-source voltage for driving high-side N-channel MOSFETs. An external capacitor (typically 100 nF) must be connected between CP and GND. If V_CP falls below V_VS + 3.5 V for >400 µs, the IC disables all gate drivers and holds them off until explicitly re-enabled via the CI pin.

How does the L9524C distinguish between shunt sense and transistor sense modes?

The MS pin voltage determines sensing mode: below 2 V enables transistor sense (using MOSFET R_DS(on) variation for overcurrent detection), while above 3 V enables shunt sense (fixed-resistor current measurement). The OCT pin then scales the overcurrent threshold accordingly-0.345–0.485 × V_OCT for transistor sense vs. 0.385–0.445 × V_OCT for shunt sense-ensuring accurate trip points across temperature.

Can the L9524C operate without a battery connection on the BAT pin?

Yes, but only in Mode 1 (relay mode with static CI signal). In Modes 2–6, BAT is mandatory: it powers internal comparators for battery voltage monitoring, enables power regulation using V_BAT, and ensures safe shutdown if main supply (VS) fails. Omitting BAT in transistor modes causes undefined behavior and disables critical diagnostics including battery undervoltage detection.

What happens during load dump events, and how does the L9524C respond?

When V_VS exceeds 28–35 V for ≥10 µs, the L9524C enters active clamping mode: all glow plugs are immediately switched on and remain latched until V_VS drops below the overvoltage threshold (18–22 V) for ≥1 ms. This prevents engine start failure during alternator load dump transients while protecting downstream circuitry via internal clamping diodes and gate driver current limiting.