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

STMicroelectronics L9911F

Name: L9911F
Brand: STMicroelectronics
SKU: L9911F
Price: 2.40 USD
Availability: InStock
Rating: 5 (2 reviews)

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Part No.:: L9911F

Manufacturer:: STMicroelectronics

Category:: Special Purpose Regulators

Package:: Multiwatt-8 (Straight Leads)

Datasheet:: L9911F.pdf

Description:: IC REG AUTO APPL 1OUT 8MULTIWATT

Quantity:: RFQ Add To RFQ list

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Inventory:1,998

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Product details

Overview

L9911F from STMicroelectronics is a monolithic automotive alternator voltage regulator with integrated high-side field driver (F+), protected diagnostic lamp/relay driver (L), field monitor output (DFM), and thermal/short-circuit protection. It delivers precise 14.0–14.8 V regulation across temperature and load, supports phase-sense-based self-start, and operates over -40 °C to +150 °C in Multiwatt8 package for engine control units.

For engineers reviewing the L9911F datasheet, L9911F pinout, L9911F application, or L9911F equivalent, this device is selected for automotive alternator control where field driver saturation voltage ≤0.6 V at 150 °C, diagnostic alarm delay of 200–500 ms, and load response timing (soft-start/attack) must be configurable via mask options without external components.

Technical Context

The L9911F implements fixed-frequency PWM field control with internal voltage sensing filtering, enabling stable regulation even with >5 V ripple on long battery cables. Its phase-sense input (Pin 1) enables self-start without auxiliary supply, requiring only VP ≥ 0.40 V and frequency ≥102 Hz to initiate regulation.

Protection architecture includes independent short-circuit detection per driver: field driver trips at 9–18 A (temperature-dependent), lamp/relay drivers use linear-mode (1 s retry) and switching-mode (<25 ms retry) protection respectively, while thermal shutdown activates at 160–190 °C with hysteresis of 2–10 °C.

Key Specifications

Parameter	Value and Actual Design Meaning
Regulated Voltage	14.0–14.8 V (Vreg-1 to Vreg-4 configurations); maintains battery charging accuracy across 7–18 V input and 1–10 A alternator current.
Field Driver Saturation	≤0.55 V @ 25 °C / 7 A; ≤0.6 V @ 150 °C / 4.5 A - ensures minimal power loss and thermal stress during high-current excitation.
Thermal Shutdown Threshold	160–190 °C; disables F+, L, and DFM outputs to prevent permanent damage under sustained overload or poor heatsinking.
Diagnostic Alarm Delay	0.2–0.5 s; prevents false warnings from transient phase dips, aligning fault reporting with real mechanical failures (e.g., belt break).
Soft-Start Timing	Configurable tST = 0 s or 2 s, tSL = 2.5 s or 9 s - matches engine cranking profiles to avoid field current surge during cold starts.
Phase Sense Thresholds	VPHL1 = 0.40 V (enable), VPHH1 = 8–10 V (phase loss detection); enables reliable self-start and alternator health monitoring.
DFM Output Frequency	125–200 Hz; provides real-time field duty-cycle feedback to ECU for closed-loop diagnostics and adaptive load management.

Pinout & Package

Package: Multiwatt8 (pin 5 GND), thermally enhanced through-hole package with exposed metal tab for direct heatsink mounting; R_{th j-case} ≤ 1.5 °C/W.

Pin/Terminal	Circuit Role	Design Meaning
1 P	Phase sense input	Accepts AC signal from alternator stator phase; triggers self-start when amplitude ≥ 0.40 V and frequency ≥ 102 Hz.
2 DFM	Field monitor open-drain output	Delivers PWM signal proportional to field duty cycle (125–200 Hz); sinks up to 14 mA for ECU feedback.
4 L	Combined lamp/relay driver	High-side relay driver and low-side lamp driver; protected against short-to-ground (1–2 A limit) and overvoltage (18–22 V cutoff).
5 GND	Case ground	Primary thermal and electrical reference; connected to heatsink for thermal dissipation and noise immunity.
7 F+	High-side field driver output	Drives alternator rotor coil; handles 15 A peak; features short-circuit protection tripping at 9–18 A depending on junction temperature.
8 B+	Sensed battery voltage input	Monitors system voltage for regulation and fault detection (UV: 7.7–9.5 V, OV: 18–22 V); tolerates 40 V load-dump transients.

Key Features

Feature	Design Value
Fully monolithic design	Integrates control logic, high-side field driver, lamp/relay drivers, diagnostics, and protection - eliminates 12+ discrete components in legacy designs.
Load response control	Mask-programmable soft-start (0/2 s delay) and soft-attack (2.5/9 s ramp) - prevents voltage dip during engine cranking and stabilizes idle charging.
Complex diagnostics	Detects belt break, brush wear, field open/short, and phase loss via combined P, B+, and F+ monitoring - reduces false alarms with 200–500 ms delay logic.
Self-start function	Wakes exclusively from phase signal (no V_B+ required); enables immediate regulation after engine start without auxiliary power sequencing.
Protected high-side relay driver	Drives relays up to 500 mA with ≤1.5 V saturation; includes short-circuit protection (1.2–3 A) and overvoltage disable above 18 V.

Applications

Engine Control Unit (ECU)

Automotive Battery Management System

Use Scenario: Real-time alternator field control and fault reporting in modern gasoline/diesel ECUs with CAN-based powertrain networks.

IC Role / Device Role / Timing Role: Primary voltage regulator and field driver; provides DFM feedback for ECU closed-loop load adaptation and phase-loss-triggered limp-home mode activation.

Use Value: Enables predictive maintenance via belt-break detection and eliminates need for external field driver MOSFETs or discrete protection circuits.

Use Scenario: Integration into 12 V battery monitoring modules that coordinate charging, load shedding, and state-of-charge estimation.

IC Role / Device Role / Timing Role: Regulator and diagnostic hub; supplies regulated voltage while feeding B+, DFM, and L status to BMS microcontroller for charge algorithm tuning.

Use Value: Delivers accurate voltage regulation (±0.2 V) and UV/OV fault flags without external references, reducing BOM count and calibration effort.

Commercial Vehicle Alternator Module

Start-Stop System Controller

Use Scenario: Heavy-duty alternator control in trucks and buses where thermal robustness and transient immunity are critical.

IC Role / Device Role / Timing Role: High-reliability field driver with 150 °C operation and 40 V load-dump tolerance; manages field excitation during rapid RPM transitions.

Use Value: Sustains regulation during 150 °C under-hood conditions and survives ISO 7637-2 pulse 5a transients without latch-up or reset.

Use Scenario: Enabling seamless restart in micro-hybrid vehicles by managing alternator field during stop/start cycles.

IC Role / Device Role / Timing Role: Soft-start/attack controller; ramps field current over 2.5–9 s to prevent voltage sag during restart and suppress alternator whine.

Use Value: Eliminates need for external timing capacitors or MCU-driven PWM sequencing - all timing is mask-configured and hardware-automated.

Equivalent & Alternatives

The following parts are listed as comparable options for similar alternator voltage regulation applications.

Alternative Part	Technical Difference	Application Difference	Selection Advice
LM34907	External N-channel field driver required; no integrated high-side F+ driver or DFM output.	Lacks self-start and phase-sense capability; requires separate enable circuitry and MCU-based diagnostics.	Select when board space allows discrete driver layout and diagnostic flexibility outweighs integration benefits.
MC33883	Includes H-bridge gate driver but no built-in voltage regulation loop or alternator-specific diagnostics.	Designed for generic motor control; lacks Vreg-1/Vreg-4 curves, load-response timing, or belt-break detection logic.	Prefer for non-alternator applications like fan or pump control where field regulation isn't needed.

Compared with LM34907 and MC33883, the L9911F uniquely integrates regulation, field driving, diagnostics, and self-start in one package - reducing PCB area by >30%, eliminating external timing components, and delivering automotive-grade fault coverage without firmware intervention.

Availability

L9911F is available at Aetrix Electronics and suitable for automotive engine control units, battery management systems, commercial vehicle alternator modules, and start-stop system controllers requiring stable component supply across extended temperature and high-transient environments.

Supply support for L9911F 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, industrial, and power management ICs, with broad portfolio certification to AEC-Q100 and ISO/TS 16949 standards.

The L9911F belongs to ST's automotive power system IC family, designed specifically for intelligent alternator control - combining precision regulation, robust protection, and ECU-ready diagnostics for next-generation vehicle electrical architectures.

FAQ

What is the purpose of the DFM pin on the L9911F?

The DFM (Field Monitor) pin is an open-drain output delivering a PWM signal (125–200 Hz) whose duty cycle reflects real-time field current excitation. It sinks up to 14 mA and provides direct feedback to the ECU for closed-loop diagnostics, load adaptation, and alternator health assessment - eliminating need for external current sensing.

How does the L9911F achieve self-start without a dedicated V_CC supply?

The L9911F uses its Phase (P) input pin to detect AC voltage from the alternator stator winding. When phase amplitude exceeds 0.40 V and frequency exceeds 102 Hz, the internal circuit wakes up and initiates regulation - enabling immediate field excitation at engine crank without auxiliary power or external biasing components.

Can the L9911F be used in 24 V commercial vehicle systems?

No - the L9911F is rated for 7–18 V operating supply (B+), with absolute maximum transient rating of 40 V for ≤500 ms. It is designed exclusively for 12 V automotive systems. For 24 V applications, ST recommends the L9912 series, which shares architecture but supports 24 V nominal operation and higher transient tolerance.

What protection mechanisms guard the F+ field driver?

The F+ driver includes short-circuit protection that trips at 9–18 A depending on junction temperature (-40 to +150 °C), thermal shutdown at 160–190 °C, and field open/short diagnostics reported via DFM and L outputs. Protection operates in switching mode with <25 ms retry time, preventing latch-up during intermittent faults.

L9911F 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:: 7V ~ 18V

Number of Outputs:: 1

Voltage - Output:: -

Operating Temperature:: -40°C ~ 150°C

Grade:: -

Qualification:: -

Mounting Type:: Through Hole

Supplier Device Package:: 8-Multiwatt

L9911F FAQ

1.How can I place an order for L9911F through Aetrix?

Please submit a Request for Quotation (RFQ) for L9911F 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 L9911F reliable?

The price and inventory of L9911F are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for L9911F is usually 5 days.

3.What payment methods are accepted for L9911F?

We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for L9911F transactions.

Note: Certain payment methods may incur a processing fee.

4.How is shipping managed for L9911F?

L9911F orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.

Once your L9911F 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 L9911F?

For technical support, including L9911F datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your L9911F requirements.

6.How does Aetrix verify that L9911F is sourced from the original manufacturer or authorized distributors?

All L9911F 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 L9911F meets industry standards.

7.What is the process for return or replacement of L9911F?

All L9911F units undergo pre-shipment inspection (PSI). If there is an issue with L9911F, 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 L9911F part is unused and in its original packaging.

Return procedure for L9911F:

1.Submit a request within 90 days.

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

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