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Home > Products > Integrated Circuits (ICs) > Power Management (PMIC) > Special Purpose Regulators

STMicroelectronics L9474N

Name: L9474N
Brand: STMicroelectronics
SKU: L9474N
Price: 2.40 USD
Availability: InStock
Rating: 5 (2 reviews)

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Part No.:: L9474N

Manufacturer:: STMicroelectronics

Category:: Special Purpose Regulators

Package:: Multiwatt-8 (Straight Leads)

Datasheet:: L9474N.pdf

Description:: IC REG AUTO APPL 1OUT 8MULTIWATT

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Product details

Overview

L9474N from STMicroelectronics is a monolithic high-side field driver voltage regulator IC for automotive alternator control. It regulates generator output by PWM-controlling rotor field current, supports RVC protocol-based setpoint selection by the ECM, features thermal shutdown (175 °C), overvoltage protection (16.5 V), and complex diagnostics including phase-sense fault detection and load response control (2.5 s ramp-up).

For engineers reviewing the L9474N datasheet, L9474N pinout, L9474N application, or L9474N equivalent, key selection criteria include its Multiwatt-8 package with integrated field driver, 8–16 V operating supply range, 6 A field current capability, reverse battery tolerance (−6 V), and diagnostic-ready L-terminal interface for warning signaling and PWM command.

Technical Context

The L9474N implements closed-loop generator regulation via variable-frequency PWM driving of the alternator's field winding, using V_GO (generator output sense) and P (phase signal) inputs to detect speed, load, and fault conditions. Its regulation loop integrates filter capacitor support at the FILTER pin and uses internal thermal sensing to disable output above 175 °C ±15 °C.

Diagnostic functionality includes real-time monitoring of field current via FM pin (0.8–2.5 kΩ impedance), L-terminal PWM decoding for setpoint adjustment (1–99% resolution, <70 mV/step), and fault latching with 1.1 s delay before activation. The device operates across −40 °C to +150 °C junction temperature and supports fail-safe open-circuit L-line behavior.

Key Specifications

Parameter	Value and Actual Design Meaning
Operating supply voltage	8–16 V - powers IC directly from generator output (V_GO) without external bias supply
Field output current limit	9 A @ T_case ≤ 25 °C - supports high-power alternators up to ~200 A output
Oscillation frequency	340–460 Hz - sets PWM carrier for field control; adjustable via external components
Overvoltage threshold	16.5 V - triggers protection and disables minimum field duty cycle to prevent battery overcharge
Thermal shutdown	175 ±15 °C - latches off F+ output until junction cools, preventing thermal runaway
Load regulation error	≤300 mV - maintains stable setpoint across 10–95% load at 6500 grpm
Phase sense threshold V_P2	7–9 V - detects loss of stator phase signal to initiate fault mode with field strobe

Pinout & Package

Package: Multiwatt-8 (pin 5 = GND), thermally enhanced through-hole package with exposed tab for heatsinking; R_th(j-case) = 1.5 °C/W enables 6 W dissipation at T_j = 150 °C.

Pin/Terminal	Circuit Role	Design Meaning
1 (P)	Phase sense input	Detects stator AC phase frequency to determine engine speed and initiate regulation; sinking current ≥0.5 mA at 1.5 V
2 (L)	Warning terminal / ECM PWM input	Bi-directional interface: outputs warning signal to BCM; accepts 128 Hz PWM for setpoint programming (1–99%)
3 (F)	Field monitor output	Current-sense feedback proportional to field current; used for diagnostics and closed-loop verification
4 (RESERVED)	Reserved terminal	No internal connection; must be left unconnected per datasheet
5 (GND)	Power ground	Main return path for field driver and internal circuitry; pin 5 is designated GND in Multiwatt-8 mechanical outline
6 (FILTER)	Regulation loop filter	Connects external RC network to stabilize voltage regulation loop and suppress oscillation
7 (F+)	Field high-side driver output	Drives alternator rotor winding directly; rated for 6 A continuous, 9 A peak; V_FON ≤ 750 mV @ 25 °C
8 (V_GO)	Generator output sense / supply	Senses battery/generator voltage for regulation; also supplies IC power (8–16 V range)

Key Features

Feature	Design Value
RVC protocol interface	Enables dynamic setpoint adjustment via 128 Hz PWM on L pin, supporting adaptive charging (e.g., cold-start boost, battery state compensation)
Load Response Control (LRC)	2.5 s controlled field ramp-up time prevents sudden torque loading on engine during high-load transients
Complex fault diagnostics	Integrated detection of open-phase (P), overvoltage (V_GO > 16.5 V), thermal overload, and L-line communication failure with 1.1 s debounce
Reverse battery protection	Withstands −6 V applied to V_GO, protecting against incorrect jump-start polarity in automotive service environments
Fail-safe L-terminal behavior	Defaults to safe setpoint (13.8 V) if L line opens - avoids generator disable seen in legacy GM systems

Applications

Automotive Alternator Regulation

ECM-Integrated Charging Control

Use Scenario: Regulating 12 V automotive alternator output across engine speeds (2,000–10,000 grpm) and loads (10–95%).

IC Role / Device Role / Timing Role: High-side field driver executing closed-loop PWM control based on V_GO, P, and L inputs; replaces discrete transistor + op-amp solutions.

Use Value: Maintains ±100 mV speed regulation and ±300 mV load regulation while enabling ECM-set adaptive voltage profiles.

Use Scenario: Enabling intelligent battery charging strategies (e.g., reduced voltage during fast-charge, elevated voltage during cold cranking) via ECM command.

IC Role / Device Role / Timing Role: RVC protocol decoder and field actuator - interprets 1–99% PWM on L pin to adjust reference voltage from 11.0 V to 15.5 V.

Use Value: Eliminates need for separate voltage reference DAC or microcontroller-based field control in cost-sensitive powertrain modules.

Generator Fault Monitoring System

Thermally Robust Field Driver Module

Use Scenario: Detecting and reporting alternator faults including phase loss, overvoltage, and thermal overload to vehicle diagnostic networks.

IC Role / Device Role / Timing Role: Integrated diagnostic engine - monitors P, V_GO, FM, and L signals; asserts fault flag after 1.1 s confirmed condition.

Use Value: Reduces BOM count by embedding diagnostics previously requiring external comparators, timers, and logic gates.

Use Scenario: Driving high-current field windings in under-hood environments where ambient temperatures exceed 105 °C.

IC Role / Device Role / Timing Role: Thermally protected high-side switch - shuts down at 175 °C and resumes only after safe cooldown, avoiding latch-up or parametric drift.

Use Value: Enables direct mounting on alternator housing without auxiliary heatsinking, simplifying mechanical integration.

Equivalent & Alternatives

The following parts are listed as comparable options for similar automotive alternator regulator applications.

Alternative Part	Technical Difference	Application Difference	Selection Advice
LM34907	Lower field current rating (4 A max), no RVC interface, analog setpoint only via resistor divider	Lacks programmable setpoint and phase-sense diagnostics; suited for fixed-voltage legacy systems	Select when RVC protocol and adaptive charging are not required and thermal budget allows lower current drive
UC3906	Requires external high-side MOSFET, no integrated thermal shutdown, no built-in overvoltage protection	Needs additional protection circuitry and microcontroller for diagnostics; higher system-level design effort	Select when full custom regulation loop design is preferred and board space permits discrete driver + controller partitioning

Compared with LM34907 and UC3906, the L9474N delivers integrated RVC decoding, embedded diagnostics, and higher field current drive in a single Multiwatt-8 package - reducing component count, improving fault coverage, and enabling ECM-coordinated charging strategies without external logic.

Availability

L9474N is available at Aetrix Electronics and suitable for automotive alternator control, ECM-integrated charging systems, and generator fault monitoring requiring stable component supply and AEC-Q100-compliant performance.

Supply support for L9474N 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, designing and manufacturing products for automotive, industrial, and power applications with emphasis on reliability and functional safety.

The L9474N belongs to ST's automotive power management IC portfolio, engineered specifically for intelligent alternator control - integrating field driving, regulation, diagnostics, and communication into a single AEC-Q100-qualified device for modern engine control units.

FAQ

What is the maximum field current the L9474N can deliver continuously?

The L9474N delivers up to 6 A continuously at case temperatures above 25 °C, with peak capability of 9 A at ≤25 °C. This is enforced by internal current limiting that activates when the field is shorted to GND. The device sustains this output while maintaining thermal shutdown at 175 °C ±15 °C and dissipating up to 6 W at T_j = 150 °C.

How does the L9474N handle an open-circuit L terminal?

When the L terminal is open-circuited, the L9474N defaults to a safe nominal setpoint of 13.8 V - avoiding the generator disable behavior seen in older GM systems. This fail-safe operation is hard-coded and requires no external pull-up or configuration, ensuring continued battery charging even if the ECM communication link fails.

Can the L9474N operate with a 24 V system?

No - the L9474N is specified for 8–16 V operating supply and transient tolerance up to 40 V (load dump), making it suitable only for 12 V automotive systems. Its internal regulators, field driver architecture, and protection thresholds (e.g., 16.5 V overvoltage) are not designed for 24 V nominal operation or associated fault conditions.

What external components are required for basic operation?

At minimum, the L9474N requires a 82 nF capacitor between FILTER and GND (per Figure 1), a flyback diode across the field winding, and proper grounding of pin 5 (GND). The P, L, and FM pins may connect directly to ECM interfaces; V_GO connects to battery/alternator output; F+ drives the field winding directly.

L9474N Specifications

Product attributes: Attribute value

Manufacturer:: STMicroelectronics

Series:: -

Package/Case:: Multiwatt-8 (Straight Leads)

Packaging:: Tube

Product Status:: Obsolete

Applications:: Power Supply, Automotive Applications

Voltage - Input:: 8V ~ 16V

Number of Outputs:: 1

Voltage - Output:: -

Operating Temperature:: -40°C ~ 150°C

Grade:: -

Qualification:: -

Mounting Type:: Through Hole

Supplier Device Package:: 8-Multiwatt

L9474N FAQ

1.How can I place an order for L9474N through Aetrix?

Please submit a Request for Quotation (RFQ) for L9474N on Aetrix. Our sales agent will provide a competitive quotation and guide you through the order confirmation once you accept the terms.

2.Are the price and stock information for L9474N reliable?

The price and inventory of L9474N are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for L9474N is usually 5 days.

3.What payment methods are accepted for L9474N?

We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for L9474N transactions.

Note: Certain payment methods may incur a processing fee.

4.How is shipping managed for L9474N?

L9474N orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.

Once your L9474N order is processed, you will receive an email with the shipment details and tracking number.

Note: Tracking information may take up to 24 hours to appear. Express delivery typically takes 3–5 business days.

5.How can I obtain technical support or documentation for L9474N?

For technical support, including L9474N datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your L9474N requirements.

6.How does Aetrix verify that L9474N is sourced from the original manufacturer or authorized distributors?

All L9474N products on Aetrix are procured from qualified distributors and authorized channels. Our dedicated quality assurance team conducts strict verification, including traceability checks and, if necessary, third-party testing. This ensures that L9474N meets industry standards.

7.What is the process for return or replacement of L9474N?

All L9474N units undergo pre-shipment inspection (PSI). If there is an issue with L9474N, returns or replacements are accepted under the following conditions:

1.Quantity discrepancies, incorrect items, or visible external defects (such as breakage or corrosion), acknowledged by Aetrix.

2.The issue is reported within 90 days of delivery.

3.The L9474N part is unused and in its original packaging.

Return procedure for L9474N:

1.Submit a request within 90 days.

2.Obtain a Return Material Authorization (RMA) from Aetrix.

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