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

STMicroelectronics L9911V

Name: L9911V
Brand: STMicroelectronics
SKU: L9911V
Price: 2.40 USD
Availability: InStock
Rating: 5 (2 reviews)

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Part No.:: L9911V

Manufacturer:: STMicroelectronics

Category:: Special Purpose Regulators

Package:: Multiwatt-8 (Straight Leads)

Datasheet:: L9911V.pdf

Description:: IC REG AUTO APPL 1OUT 8MULTIWATT

Quantity:: RFQ Add To RFQ list

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Inventory:1,995

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Product details

Overview

L9911V from STMicroelectronics is a monolithic automotive alternator voltage regulator with integrated high-side field driver (F+), protected diagnostic lamp/relay driver (L), phase-sense input (P), and field monitor output (DFM). It delivers precise 14.35–14.65 V regulation (Vreg-2) at 10 A/6000 rpm, features thermal shutdown at 160–190 °C, and supports load response control with soft-start delay up to 2 s - deployed in 12 V gasoline/diesel engine charging systems.

For engineers reviewing the L9911V datasheet, L9911V pinout, L9911V application, or L9911V equivalent, key selection criteria include field driver saturation voltage (≤0.55 V @ 25 °C/7 A), phase-loss detection thresholds (VPHH1 = 8–10 V), DFM open-drain switching frequency (125–200 Hz), and EN-2 enable frequency range (124–166 Hz) for engine-speed-dependent regulation startup.

Technical Context

The L9911V implements fixed-frequency PWM control of the alternator field winding via its high-side F+ driver, with internal filtering enabling stable operation despite >5–6 V ripple on long battery cables. Regulation is referenced to three selectable Vreg curves (Vreg-1 to Vreg-4), each with defined thermal drift (e.g., −11.8 to −8.2 mV/°C for Vreg-2).

Phase-based diagnostics detect belt breakage, brush wear, or field interruption by monitoring P-pin voltage against VPHH1 (8–10 V) and VPHL1 (0.40 V), with fault reporting delayed 200–500 ms to suppress transients. Load response is managed through mask-programmable soft-start (tST_1/tST_2) and soft-attack (tSL_1/tSL_2) timing options.

Key Specifications

Parameter	Value and Actual Design Meaning
Vreg-2	14.35–14.65 V @ 10 A, 6000 rpm, 23 °C - primary regulation curve for mid-load automotive charging
F+ saturation voltage	≤0.55 V @ 7 A, 25 °C - ensures low conduction loss and minimal heat generation in field driver
Thermal shutdown threshold	160–190 °C - disables F+, L, and DFM drivers to prevent permanent damage during overload
Phase sense thresholds	VPHH1 = 8–10 V (high), VPHL1 = 0.40 V (low) - enables reliable alternator rotation and fault detection
DFM output frequency	125–200 Hz @ Ialt = 1–9 A - provides real-time field current feedback for ECU monitoring
EN-2 enable frequency	124–166 Hz - defines minimum engine speed (≈1450 rpm, 6-pole) to initiate regulation
Load response timing	tST_2 = 1.73–2.35 s, tSL_1 = 2.13–2.87 s - programmable soft-start/attack for reduced mechanical stress on belts and pulleys

Pinout & Package

Package: Multiwatt8 (pin 5 GND), thermally enhanced through-hole package with case-grounded tab; R_{th j-case} ≤ 1.5 °C/W enables direct heatsinking to chassis ground.

Pin/Terminal	Circuit Role	Design Meaning
1 (P)	Phase sense input	Detects alternator AC phase voltage to confirm rotation and trigger self-start; requires ≥0.40 V amplitude
2 (DFM)	Field monitor output	Open-drain output proportional to field current duty cycle; used for ECU diagnostics and closed-loop control
4 (L)	Lamp/relay driver terminal	Configurable low-side lamp driver or high-side relay driver; protected against short-to-ground and overvoltage
5 (GND-case)	Case ground	Thermal and electrical reference point; must be connected to vehicle chassis for thermal dissipation and noise immunity
7 (F+)	High-side field driver output	Drives alternator rotor coil directly; integrates short-circuit protection with <25 ms retry time
8 (B+)	Sensed power supply	Monitors battery voltage for regulation, under/overvoltage diagnosis, and load-response control

Key Features

Feature	Design Value
Self-start function	Wakes exclusively from P-pin phase signal - eliminates need for ignition-switched V_BAT biasing
Complex diagnostics	Detects 7 distinct faults (belt break, brush wear, field open/short, battery undervoltage) with delayed alarm (200–500 ms)
Load response control	Mask-selectable soft-start (0–2 s delay) and soft-attack (2.1–10.4 s ramp) prevents torque shock during engine cranking
Thermal + short-circuit protection	Independent shutdown of F+, L, and DFM at 160–190 °C; field driver retries <25 ms after short, lamp driver retries 1 s
Robust EMC design	Integrated voltage-sensing filter tolerates >5–6 V ripple on long cables - no external capacitor required in standard installations

Applications

Gasoline Engine Charging System

Diesel Engine Charging System

Use Scenario: 12 V alternator in passenger car with variable engine speed (0–6000 rpm) and dynamic load (headlights, HVAC, infotainment).

IC Role / Device Role / Timing Role: Primary voltage regulator controlling field current via F+ PWM; uses P-pin phase signal for self-start and RPM-synchronized load response.

Use Value: Maintains 14.35–14.65 V output across 5–18 V input and 1–10 A load, minimizing battery sulfation and headlight flicker during idle-stop cycles.

Use Scenario: Heavy-duty diesel truck alternator subject to high ambient temperature (>105 °C under hood) and frequent cold cranking.

IC Role / Device Role / Timing Role: High-reliability field controller with thermal shutdown at 160–190 °C and robust phase-loss detection to prevent false warnings during low-RPM operation.

Use Value: Enables continuous charging down to 400 rpm via EN-2 frequency setting while surviving 150 °C junction temperature per AEC-Q100 Grade 0 requirements.

Start-Stop Vehicle Charging

Commercial Vehicle Diagnostic Interface

Use Scenario: Micro-hybrid system requiring seamless restart after engine-off; alternator must re-engage within 300 ms of crank request.

IC Role / Device Role / Timing Role: Regulator with programmable tST_1 = 0 s and tSL_1 = 2.13–2.87 s soft-attack - ensures field current ramps without mechanical jerk.

Use Value: Eliminates belt squeal and starter motor load spikes by synchronizing field excitation with crankshaft angular position via DFM feedback.

Use Scenario: Telematics gateway monitoring alternator health in fleet vehicles using CAN bus; requires real-time field status and fault logs.

IC Role / Device Role / Timing Role: Smart regulator providing DFM pulse train (125–200 Hz) and L-driver-controlled warning lamp for ECU-level diagnostics.

Use Value: Delivers field current waveform data and 7-fault classification (e.g., "belt break" vs "brush wear") without external ADC or logic - reducing BOM cost by $1.20/unit.

Equivalent & Alternatives

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

Alternative Part	Technical Difference	Application Difference	Selection Advice
LM34907T	Single-channel high-side driver only; no integrated regulation, phase sense, or diagnostics	Requires external op-amp, comparator, and microcontroller for full alternator control	Select when custom regulation algorithm or non-standard Vreg curve is needed; adds ~40 mm² PCB area and firmware development
UC3906	Analog-only regulator IC; no integrated F+ driver, DFM output, or thermal shutdown - requires external MOSFET and discrete protection	Limited to legacy designs; lacks AEC-Q100 qualification and modern fault diagnostics	Choose only for repair of pre-2005 vehicles; not suitable for new designs due to missing short-circuit retry and phase-loss detection

Compared with LM34907T and UC3906, the L9911V integrates complete alternator control - including regulation, field driving, diagnostics, and load response - in one AEC-Q100 qualified Multiwatt8 package, reducing system complexity, validation effort, and failure-in-field risk.

Availability

L9911V is available at Aetrix Electronics and suitable for gasoline engine charging systems, diesel commercial vehicle alternators, start-stop micro-hybrid platforms, and telematics-based diagnostic interfaces requiring stable component supply across automotive production lifecycles.

Supply support for L9911V 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 analog, power, and microcontroller solutions, with over 30 years of experience in powertrain and body electronics.

The L9911V belongs to ST's Automotive Power Management portfolio, designed specifically for intelligent alternator control in 12 V ICE and mild-hybrid vehicles - emphasizing functional safety, thermal resilience, and diagnostic completeness.

FAQ

What is the purpose of the DFM pin on the L9911V?

The DFM (Field Monitor) pin is an open-drain output that pulses at 125–200 Hz with duty cycle proportional to field current. It provides real-time feedback to the ECU for closed-loop regulation, alternator health monitoring, and fault signature analysis - eliminating need for external current shunts or Hall sensors.

How does the L9911V achieve self-start without an ignition signal?

The L9911V wakes from standby solely upon detecting a valid phase signal (P pin) with amplitude ≥0.40 V and frequency ≥108 Hz (EN-1) or ≥124 Hz (EN-2). This allows immediate field excitation at engine cranking - no external wake-up line or V_BAT sequencing is required.

Can the L9911V operate with long battery cables exceeding 2 meters?

Yes - its integrated voltage-sensing filter tolerates >5–6 V ripple caused by long cable impedance. In standard applications, no external capacitor is needed. Only when cable length exceeds 5 meters and ripple exceeds 6 V should a 2.2 μF capacitor be added between B+ and GND.

What fault conditions trigger the L-terminal warning lamp?

The L terminal illuminates for seven confirmed faults: alternator belt break, brush wear/open, field open circuit, field short to battery or ground, and battery under/overvoltage. Each fault is validated for ≥200 ms before activation to reject transient noise - preventing false warnings during cranking or load dump.

L9911V Specifications

Product attributes: Attribute value

Manufacturer:: STMicroelectronics

Series:: -

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

Packaging:: Tube

Product Status:: Active

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

L9911V FAQ

1.How can I place an order for L9911V through Aetrix?

Please submit a Request for Quotation (RFQ) for L9911V 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 L9911V reliable?

The price and inventory of L9911V are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for L9911V is usually 5 days.

3.What payment methods are accepted for L9911V?

We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for L9911V transactions.

Note: Certain payment methods may incur a processing fee.

4.How is shipping managed for L9911V?

L9911V orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.

Once your L9911V 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 L9911V?

For technical support, including L9911V datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your L9911V requirements.

6.How does Aetrix verify that L9911V is sourced from the original manufacturer or authorized distributors?

All L9911V 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 L9911V meets industry standards.

7.What is the process for return or replacement of L9911V?

All L9911V units undergo pre-shipment inspection (PSI). If there is an issue with L9911V, 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 L9911V part is unused and in its original packaging.

Return procedure for L9911V:

1.Submit a request within 90 days.

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

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