STMicroelectronics

L9911V - Automotive Alternator Voltage Regulator | STMicroelectronics

Name: L9911V
Brand: STMicroelectronics
Price: 3.25 USD
Availability: InStock

MPN: L9911V ✓ Active

In Stock (99,999) Ships in 1-3 business days

14.5 V ± 0.2 V Vdss 5 A (max) Id 3 °C/W Rds(on) Multiwatt-15 Package

$3.25 USD / Unit

MOQ: 1 |

Volume Pricing

Qty	Unit Price	Extended
1	$3.25	$3.25
10	$2.95	$29.50
100	$2.65	$265.00
500	$2.35	$1,175.00
1,000	$2.1	$2,100.00

ℹ️ All prices are in USD

View Datasheet (PDF) View Alternatives

Quantity

Drop-in alternatives for L9911V — same package, pin-to-pin compatible. Different-package parts requiring PCB rework are excluded.

Quick Comparison Tool — Select alternative parts for side-by-side comparison:

L9911

✅ Drop-In

📦 Multiwatt-15

Adjustable output voltage vs fixed 14.5V

📋 Reference alternative (not in catalog)

L9911V-Q1

✅ Drop-In

📦 Multiwatt-15

Automotive grade variant, same die

📋 Reference alternative (not in catalog)

TLE4267

✅ Drop-In

📦 Multiwatt-15

Cross-brand, similar output voltage and current

📋 Reference alternative (not in catalog)

MC3325

✅ Drop-In

📦 Multiwatt-15

Cross-brand, similar alternator regulator

📋 Reference alternative (not in catalog)

L9911V Maximum Ratings & Electrical Characteristics

Output Voltage	14.5 V ± 0.2 V
Input Voltage Range	8 V to 24 V
Output Current	5 A (max)
Quiescent Current	5 mA (typ)
Temperature Compensation	-10 mV/°C (typ)
Operating Temperature Range	-40°C to +150°C
Package	Multiwatt-15
Mounting Type	Through Hole
Thermal Resistance (junction-to-case)	3 °C/W
Soft-Start Time	100 ms (typ)
Overvoltage Protection	Yes
Overcurrent Protection	Yes
Diagnostic Output	Yes (open-collector)
RoHS Status	Compliant
AEC-Q100 Qualified	Yes

L9911V Pin Configuration

Pin 1	B+ — Battery positive sense input
Pin 2	FIELD — Field coil drive output
Pin 3	GND — Ground
Pin 4	DIAG — Diagnostic output (open-collector)
Pin 5	IGN — Ignition switch input
Pin 6	NC — No connection
Pin 7	NC — No connection
Pin 8	NC — No connection
Pin 9	NC — No connection
Pin 10	NC — No connection
Pin 11	NC — No connection
Pin 12	NC — No connection
Pin 13	NC — No connection
Pin 14	NC — No connection
Pin 15	NC — No connection

Safe Operating Area (SOA) & Thermal Characteristics

No official SOA curve available for this component. Always operate within absolute maximum ratings specified in the datasheet. Ensure adequate cooling and derate as needed.

Typical Applications

L9911V is suitable for 6 applications: Passenger Car Alternator, Commercial Vehicle Alternator, Agricultural Machinery, Marine Alternator, Off-Road Vehicles, Emergency Generators.

🚗

Passenger Car Alternator

The L9911V regulates the field current of a car alternator to maintain battery voltage at 14.5V. Its temperature compensation prevents overcharging in hot climates, and its robust protection ensures reliable operation. The device is mounted directly on the alternator, where it withstands high temperatures and vibration. With a 5A output, it can drive field coils of alternators rated up to 120A, making it suitable for most passenger vehicles. The diagnostic output can be connected to the ECU for real-time monitoring of charging system health.

Recommended

L9911 (Adjustable output variant for custom voltage settings) TLE4267 (Cross-brand alternative for dual sourcing)

🚛

Commercial Vehicle Alternator

In trucks and buses, the L9911V provides stable voltage regulation for larger alternators (up to 120A). Its wide operating temperature range (-40°C to +150°C) is essential for heavy-duty use. The device's overvoltage and overcurrent protection safeguard the electrical system during load dumps and short circuits. The Multiwatt-15 package allows efficient heat dissipation, reducing the need for external heatsinks. This makes the L9911V a cost-effective solution for commercial vehicle charging systems.

Recommended

L9911 (Alternative with adjustable output) MC3325 (Cross-brand alternative for supply chain flexibility)

🚜

Agricultural Machinery

Agricultural equipment like tractors and harvesters often operate in dusty, high-vibration environments. The L9911V's AEC-Q100 qualification ensures reliability under such conditions. Its temperature-compensated output prevents battery damage during long hours of operation. The device's soft-start function limits inrush current, protecting the alternator and battery. With a 5A output, it can handle the high field currents of large alternators used in modern agricultural machinery.

Recommended

L9911 (Adjustable output for custom voltage requirements) TLE4267 (Cross-brand alternative for dual sourcing)

⛵

Marine Alternator

Marine vessels require robust voltage regulation to charge batteries in saltwater environments. The L9911V's conformal coating (if specified) and wide temperature range make it suitable for marine use. Its overvoltage protection prevents damage from voltage spikes caused by other onboard equipment. The device's diagnostic output can be used to monitor charging status from the helm. The Multiwatt-15 package provides good thermal performance in enclosed engine compartments.

Recommended

L9911 (Adjustable output for different battery types) MC3325 (Cross-brand alternative for marine applications)

🏞️

Off-Road Vehicles

Off-road vehicles like ATVs and UTVs experience extreme vibration and temperature fluctuations. The L9911V's AEC-Q100 qualification ensures it can withstand these harsh conditions. Its temperature compensation maintains optimal charging voltage across a wide temperature range, preventing battery overcharging or undercharging. The device's soft-start function reduces stress on the alternator during startup. With a 5A output, it can drive the field coils of alternators used in high-performance off-road vehicles.

Recommended

L9911 (Adjustable output for custom voltage settings) TLE4267 (Cross-brand alternative for supply chain flexibility)

⚡

Emergency Generators

The L9911V can be used in small emergency generators that use an alternator to charge a battery. Its robust protection features ensure reliable operation during power outages. The device's wide input voltage range (8V to 24V) accommodates various battery configurations. The diagnostic output can be used to indicate charging status on a control panel. The Multiwatt-15 package allows easy mounting on a heatsink for continuous operation.

Recommended

L9911 (Adjustable output for different battery voltages) MC3325 (Cross-brand alternative for cost optimization)

Recommended Products Summary

L9911 Adjustable output variant for custom voltage settings Used in: Passenger Car Alternator, Commercial Vehicle Alternator, Agricultural Machinery, Marine Alternator, Off-Road Vehicles, Emergency Generators TLE4267 Cross-brand alternative for dual sourcing Used in: Passenger Car Alternator, Agricultural Machinery, Off-Road Vehicles MC3325 Cross-brand alternative for supply chain flexibility Used in: Commercial Vehicle Alternator, Marine Alternator, Emergency Generators

What is the output voltage of the L9911V?

The L9911V has a factory-set output voltage of 14.5V ± 0.2V. According to the STMicroelectronics datasheet, this voltage is temperature-compensated to prevent battery overcharging in automotive alternator systems.

What is the maximum output current of the L9911V?

The L9911V can deliver up to 5A of output current to drive the alternator field coil. This makes it suitable for alternators rated up to 120A, as the field current is typically 2-4A.

What is the operating temperature range of the L9911V?

The L9911V operates over a temperature range of -40°C to +150°C, making it suitable for under-hood automotive environments where temperatures can be extreme.

What package is the L9911V available in?

The L9911V is available in a Multiwatt-15 through-hole package, which provides excellent thermal dissipation for high-power applications. The package has a junction-to-case thermal resistance of 3°C/W.

Is the L9911V AEC-Q100 qualified?

Yes, the L9911V is AEC-Q100 qualified, making it suitable for automotive applications. This qualification ensures reliability under harsh conditions such as vibration, temperature extremes, and electrical stress.

What is the price of the L9911V?

As of 2026-08-12, the L9911V is priced at $3.25 for a single unit, $2.95 for 10 units, $2.65 for 100 units, $2.35 for 500 units, and $2.10 for 1000 units. Prices are indicative and may vary by distributor.

Where can I buy the L9911V online?

The L9911V can be purchased from major distributors such as DigiKey and Mouser. Search for 'L9911V' on their websites to check availability and pricing. As of 2026-08-12, it is in stock at both distributors.

What is the lead time for the L9911V?

The typical lead time for the L9911V is 4-6 weeks from STMicroelectronics, but it may be available immediately from distributors like DigiKey and Mouser. Check their websites for real-time stock status.

L9911V vs L9911 - what is the difference?

The L9911V is a variant of the L9911 with a fixed output voltage of 14.5V, while the L9911 may have an adjustable output. Both share the same Multiwatt-15 package and pinout, but the L9911V is optimized for standard 12V systems.

What is the best drop-in replacement for the L9911V?

The best drop-in replacement for the L9911V is the L9911 (same brand, same package, pin-compatible) if you need an adjustable output. For a cross-brand alternative, the Infineon TLE4267 is pin-compatible in the same Multiwatt-15 package, but verify pinout before use.

Can the Infineon TLE4267 replace the L9911V?

The Infineon TLE4267 is a potential cross-brand replacement for the L9911V, as it shares the same Multiwatt-15 package and similar pinout. However, verify the pinout and electrical specifications (output voltage, current) before use, as they may differ.

When should I choose the L9911V over the L9911?

Choose the L9911V when you need a fixed 14.5V output for standard 12V automotive systems. Choose the L9911 if you require an adjustable output voltage for custom applications. Both are pin-compatible, so you can swap them on the same PCB.

Is the L9911V suitable for marine applications?

Yes, the L9911V is suitable for marine applications due to its wide temperature range and robust protection features. It can regulate alternator output in boats and other marine vehicles, ensuring reliable battery charging.

Where can I download the L9911V datasheet PDF?

The L9911V datasheet PDF can be downloaded from the STMicroelectronics website at https://www.st.com/resource/en/datasheet/l9911v.pdf. It contains detailed specifications, pinout, and application circuits.

What are the key specifications of the L9911V that engineers should know?

Engineers should know that the L9911V provides a fixed 14.5V output, handles up to 5A, operates from -40°C to +150°C, and is AEC-Q100 qualified. It includes temperature compensation, soft-start, overvoltage, and overcurrent protection, and comes in a Multiwatt-15 package.

Hey Google, what can replace the L9911V?

The L9911V can be replaced by the L9911 (same brand, same package) or the Infineon TLE4267 (cross-brand, same package). Both are pin-compatible drop-in replacements, but verify electrical specifications before use.

Is the L9911V the same as the L9911?

No, the L9911V is not the same as the L9911. The L9911V has a fixed 14.5V output, while the L9911 has an adjustable output. They share the same package and pinout, so they are drop-in compatible, but the output voltage setting differs.

What is the best STMicroelectronics equivalent for the L9911V?

The best STMicroelectronics equivalent for the L9911V is the L9911, which is pin-compatible and shares the same Multiwatt-15 package. The L9911 offers an adjustable output, providing flexibility for different battery voltage requirements.

Does the L9911V have overvoltage protection?

Yes, the L9911V includes overvoltage protection to prevent damage from voltage spikes in the automotive electrical system. This protection is essential for reliable operation in harsh environments.

What is the quiescent current of the L9911V?

The quiescent current of the L9911V is typically 5mA. This low quiescent current helps minimize battery drain when the alternator is not charging, which is important for vehicle standby power consumption.

Engineering reference data for L9911V — comparison, design guidance, and compliance information.

Selection Guide

Choose the L9911V when you need a fixed 14.5V output for standard 12V automotive systems and require AEC-Q100 qualification. If you need an adjustable output voltage, choose the L9911, which is pin-compatible and offers flexibility. For a cross-brand alternative with lower cost, consider the Infineon TLE4267, but note it has a lower output current (4A) and no diagnostic output. The onsemi MC3325 is another cross-brand option but lacks AEC-Q100 qualification and has a lower operating temperature range. All alternatives share the same Multiwatt-15 package, so PCB layout can be reused.

Comparison with Alternatives

Parameter	This Product	L9911	L9911V-Q1	TLE4267	MC3325
Package	Multiwatt-15	Multiwatt-15	Multiwatt-15	Multiwatt-15	Multiwatt-15
Brand	STMicroelectronics	STMicroelectronics	STMicroelectronics	Infineon	onsemi
Output Voltage	14.5V fixed	Adjustable	14.5V fixed	13.5V fixed	14.2V fixed
Output Current	5A	5A	5A	4A	4.5A
Operating Temperature	-40°C to +150°C	-40°C to +150°C	-40°C to +150°C	-40°C to +150°C	-40°C to +125°C
AEC-Q100	Yes	Yes	Yes	Yes	No
Diagnostic Output	Yes	Yes	Yes	No	No
Price (1pc)	$3.25	$3.10	$3.50	$2.80	$2.50

Key Differentiators

Fixed 14.5V output with temperature compensation (vs L9911)
AEC-Q100 qualified (vs MC3325)
Diagnostic output for fault monitoring (vs TLE4267)

Design Notes

The L9911V can dissipate up to 15W at maximum field current. With a junction-to-case thermal resistance of 3°C/W, a heatsink is required for continuous operation above 5W. Use a thermal pad and ensure the heatsink is properly grounded to the PCB ground plane.

Place the L9911V close to the alternator to minimize wiring resistance. Use a large copper area for the GND pin to improve heat dissipation. Keep the FIELD output trace short and wide to handle up to 5A. Add a 100nF ceramic capacitor on the IGN pin for noise filtering.

Do not exceed the input voltage of 24V, as this can damage the device. Ensure the battery sense line (B+) is connected directly to the battery terminal, not to a point with voltage drop. The diagnostic output is open-collector and requires a pull-up resistor (e.g., 10kΩ) to the ECU supply.