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Home > Products > Integrated Circuits (ICs) > Power Management (PMIC) > Power Management - Specialized

STMicroelectronics L9915B

Name: L9915B
Brand: STMicroelectronics
SKU: L9915B
Price: 2.40 USD
Availability: InStock
Rating: 5 (2 reviews)

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Part No.:: L9915B

Manufacturer:: STMicroelectronics

Category:: Power Management - Specialized

Package:: Multiwatt-8 (Straight Leads)

Datasheet:: L9915B.pdf

Description:: IC REG CTAVR C-TERM MULTIWATT8

Quantity:: RFQ Add To RFQ list

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Product details

Overview

L9915B from STMicroelectronics is a monolithic C-terminal alternator voltage regulator (CTAVR) for automotive 12 V/24 V systems. It performs closed-loop regulation of generator output via PWM-controlled high-side field driver (F pin), integrates field short-circuit protection, thermal shutdown (160–190 °C), and ECU-synchronized voltage set-point control via C-terminal protocol (100–500 Hz). Used in engine control modules to maintain stable battery charging under cranking, load dump, and wide-temperature conditions.

For engineers reviewing the L9915B datasheet, L9915B pinout, L9915B application, or L9915B equivalent, this device supports protocol-driven external regulation (7–93% C-pin duty cycle), internal thermally compensated regulation (−5 to −9 mV/°C drift), self-start functionality (fPH ≥ 255 Hz), and integrated lamp driver with wake-up capability during battery disconnect.

Technical Context

The L9915B implements dual-mode regulation: external mode uses C-terminal PWM input (100–500 Hz, 7–93% duty) to select set-point voltage (11.5–15.5 V), while internal mode defaults to 14.55 V ±0.18 V with −7 mV/°C thermal drift. Phase sensing on PH pin (300–450 mV threshold, 102–138 Hz pre-excitation exit) enables RPM-synchronized control and phase regulation (VPprTh = 7.7 V).

Its high-side field driver (F pin) delivers up to 7 A sink current with 0.55 V saturation at 25 °C, features over-current protection (8.5–15 A trip), retry timing (40 ms), and load response control (LRC) triggered above 238 Hz. The L pin provides key-on detection (0.8 V threshold) and warning lamp drive with self-bias operation when B pin is unconnected.

Key Specifications

Parameter	Value and Actual Design Meaning
Regulation Modes	External (C-terminal protocol) and internal (thermal compensation); no ECU communication required for basic function
Set-Point Voltage Range	11.5–15.5 V externally programmable; 14.55 V ±0.18 V internally, flat across temperature
Field Driver Output	High-side PWM switch (F pin), 7 A max sink, 0.55 V V_Fsat @ 25 °C, 250 Hz switching frequency
Phase Sense Input (PH)	Hysteresis buffer (300–450 mV high threshold), 120 Hz min pre-excitation exit, supports RPM calculation via f_PH × 60 / N
Thermal Protection	Shutdown at 160–190 °C with 2–10 °C hysteresis; 4 W max power dissipation at T_case = 150 °C
Lamp Driver (L pin)	Self-bias capable (VB open), 1.2 V saturation @ 0.5 A, 440 ms alarm validation time, 1.5 A over-current limit
C-Terminal Protocol	100–500 Hz input, 7–93% duty cycle range, 30–100 ms delay to switch from external to internal regulation

Pinout & Package

Package: Multiwatt-8 (MW8) with exposed tab, pin 5 as GND, RoHS-compliant ECOPACK®. Thermal resistance junction-to-case: 1.5 °C/W.

Pin/Terminal	Circuit Role	Design Meaning
1 PH	Phase sense input	Detects alternator rotor speed via stator phase waveform; triggers regulation start/stop and LRC
2 XX	Reserved	Must be connected to GND; no internal connection or function
3 C	C-terminal protocol input	Accepts ECU PWM signal (100–500 Hz) to select regulated voltage set-point
4 FM	Field monitor output	PWM feedback to ECU (212–287 Hz, 5–95% duty) indicating field driver activity
5 GND	Regulator ground reference	Main return path for field, lamp, and internal circuits; pin 5 is thermal and electrical ground
6 F	High-side field driver output	Sinks current into alternator field winding; includes over-current protection and retry timing
7 L	Key sense & warning lamp driver	Detects ignition key-on (0.8 V threshold); drives dashboard lamp even during battery disconnect
8 B	Battery supply & voltage sense	Connects to battery+; monitors VB for under-voltage (6–7 V), over-voltage (16.2–17.9 V), and cranking security

Key Features

Feature	Design Value
Protocol-driven regulation	Enables ECU-dynamic voltage tuning (11.5–15.5 V) without hardware change; supports adaptive charging strategies
Self-start capability	Activates regulation autonomously when PH frequency exceeds 255 Hz, enabling operation with failed C-wire or ECU
Field short-circuit protection	Shuts down F pin on sustained over-current (>8.5 A), retries after 40 ms, prevents MOSFET destruction
Thermally compensated reference	Internal voltage reference drifts −7 mV/°C, maintaining ±0.18 V accuracy from −40 to +150 °C
Lamp driver with self-bias	Drives warning lamp directly from L pin using internal charge pump; operates even if B pin is disconnected

Applications

Engine Control Module (ECM)

Start-Stop System Regulator

Use Scenario: Integrated into diesel/gasoline ECMs to manage alternator output during transient engine loads, cold cranking, and idle-stop events.

IC Role / Device Role / Timing Role: Primary voltage regulator controlling field current via high-side PWM; synchronizes with PH signal for RPM-based excitation timing.

Use Value: Maintains 14.55 V battery charge during cranking (VB ≥ 6.5 V) and prevents over-voltage damage during load dump (VB ≤ 17.9 V).

Use Scenario: Enables seamless restart in 12 V micro-hybrid vehicles by sustaining regulated voltage during engine-off periods and rapid re-excitation at restart.

IC Role / Device Role / Timing Role: Dual-mode regulator: uses C-terminal protocol during normal operation and self-start mode when C-wire is inactive during stop phase.

Use Value: Reduces restart latency by initiating field excitation within 50 ms of PH signal detection (≥255 Hz), independent of ECU wake-up timing.

Commercial Vehicle Charging System

Heavy-Duty Alternator Diagnostic Module

Use Scenario: Deployed in trucks and buses with dual-battery systems to regulate 24 V alternators under high ambient temperatures (up to +150 °C junction).

IC Role / Device Role / Timing Role: High-reliability CTAVR with thermal shutdown (175 °C typ) and robust ESD protection (±4 kV HBM) for harsh under-hood environments.

Use Value: Ensures continuous charging during extended idling by sustaining 4 W power dissipation at 150 °C case temperature without derating.

Use Scenario: Embedded in service tools to validate alternator health by monitoring FM pin PWM duty cycle and correlating with PH frequency and VB trends.

IC Role / Device Role / Timing Role: Field monitor interface: FM pin outputs real-time field driver status (212–287 Hz, 5–95% duty) synchronized to PH input.

Use Value: Enables diagnostic detection of open-field windings (FM silence), shorted fields (FM stuck high), and regulator misalignment (FM duty vs. VB deviation).

Equivalent & Alternatives

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

Alternative Part	Technical Difference	Application Difference	Selection Advice
LM34902QDGQRQ1	Low-side field driver; requires external high-side switch; no C-terminal protocol support; only internal regulation (14.25 V fixed)	Lacks ECU programmability and PH-based phase regulation; suitable only for legacy fixed-setpoint systems	Select when cost sensitivity outweighs need for adaptive charging or diagnostics
UC3906PW	Analog controller IC; requires external MOSFETs, op-amps, and comparators; no integrated protection or lamp driver	No monolithic integration: needs ≥8 external components for basic function; no FM or self-bias lamp capability	Choose only for custom designs requiring full analog control loop visibility and tuning

Compared with L9915B, LM34902QDGQRQ1 lacks protocol-driven voltage selection and phase-synchronized regulation, while UC3906PW demands extensive external circuitry and offers no built-in fault reporting-making L9915B the only monolithic solution with integrated diagnostics, self-start, and ECU coordination.

Availability

L9915B is available at Aetrix Electronics and suitable for automotive engine control modules, start-stop systems, commercial vehicle charging systems, and heavy-duty alternator diagnostic modules requiring stable component supply across extended temperature and voltage transients.

Supply support for L9915B 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, power, and embedded solutions, with broad portfolio coverage from discrete devices to system-on-chip platforms.

L9915B belongs to ST's automotive power regulation product line, designed specifically for intelligent alternator control in modern ICE and micro-hybrid vehicles where ECU coordination, thermal resilience, and functional safety are critical.

FAQ

What is the purpose of the "XX" pin (Pin 2) on the L9915B?

Pin 2 is a reserved terminal with no internal connection and must be tied to GND per datasheet Table 2. It serves as a mechanical stabilization point in the Multiwatt-8 package and has no electrical function-leaving it floating violates layout requirements and may impact thermal performance or EMI behavior.

How does the L9915B handle battery disconnection during vehicle operation?

When the B pin loses connection, the L pin activates its self-bias circuit to drive the warning lamp using internal charge-pump energy, providing immediate driver alert. Simultaneously, the device enters low-power standby (≤350 μA), preserving residual energy in onboard capacitance until battery reconnection restores full regulation.

Can the L9915B operate without an ECU connection on the C pin?

Yes-the L9915B defaults to internal regulation mode with 14.55 V set-point and −7 mV/°C thermal drift when C pin is open, below 7% duty, or above 93% duty. This ensures fail-safe battery charging even with ECU communication failure or wiring faults.

What is the significance of the PH pin's hysteresis (fPHYS = 10–30 Hz)?

The PH hysteresis prevents oscillation during marginal alternator speeds by enforcing a 10–30 Hz gap between pre-excitation entry (fPLPrex) and exit (fPHPrex) thresholds. This ensures stable transition into regulation only when rotor speed is reliably sustained above 120 Hz, avoiding false starts during cranking or belt slip.

L9915B Specifications

Product attributes: Attribute value

Manufacturer:: STMicroelectronics

Series:: -

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

Packaging:: Tube

Product Status:: Active

Applications:: -

Current - Supply:: -

Voltage - Supply:: 6V ~ 18V

Operating Temperature:: -40°C ~ 150°C

Grade:: Automotive

Qualification:: -

Mounting Type:: Through Hole

Supplier Device Package:: 8-Multiwatt

L9915B FAQ

1.How can I place an order for L9915B through Aetrix?

Please submit a Request for Quotation (RFQ) for L9915B 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 L9915B reliable?

The price and inventory of L9915B are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for L9915B is usually 5 days.

3.What payment methods are accepted for L9915B?

We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for L9915B transactions.

Note: Certain payment methods may incur a processing fee.

4.How is shipping managed for L9915B?

L9915B orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.

Once your L9915B 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 L9915B?

For technical support, including L9915B datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your L9915B requirements.

6.How does Aetrix verify that L9915B is sourced from the original manufacturer or authorized distributors?

All L9915B 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 L9915B meets industry standards.

7.What is the process for return or replacement of L9915B?

All L9915B units undergo pre-shipment inspection (PSI). If there is an issue with L9915B, 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 L9915B part is unused and in its original packaging.

Return procedure for L9915B:

1.Submit a request within 90 days.

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

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