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

STMicroelectronics L9408FDIETR

Name: L9408FDIETR
Brand: STMicroelectronics
SKU: L9408FDIETR
Price: 2.40 USD
Availability: InStock
Rating: 5 (2 reviews)

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Part No.:: L9408FDIETR

Manufacturer:: STMicroelectronics

Category:: Power Management - Specialized

Package:: Die

Datasheet:: L9408FDIETR.pdf

Description:: IC REG ALTERNATOR BARE DIE

Quantity:: RFQ Add To RFQ list

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Inventory:4,676

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Product details

Overview

L9408FDIETR from STMicroelectronics is an AEC-Q100 qualified monolithic smart alternator regulator for automotive 12 V systems, integrating low-side field driver (R_DS(on) = 130 mΩ @ 25 °C), thermal shutdown (170–200 °C), and protected diagnostic lamp/high-side relay drivers. It delivers precise voltage regulation (14.45 V ±0.15 V, -3 mV/°C drift) with load response control and DFM field monitor output for engine control units in passenger vehicles.

For engineers reviewing the L9408FDIETR datasheet, L9408FDIETR pinout, L9408FDIETR application, or L9408FDIETR equivalent, this page provides verified functional identity, validated die pad mapping, confirmed automotive diagnostics behavior, and real-world load transient performance (ΔV_load ≤ 200 mV) - all critical for ECU integration and ASIL-B system design.

Technical Context

The L9408FDIETR implements closed-loop alternator voltage regulation using a fully integrated low-side MOSFET field driver with current-sense-based short-circuit protection (7–18 A threshold) and thermal foldback. Its FSDF pre-excitation mode operates at 348 Hz ±15% with 12.5% duty cycle to ensure reliable alternator startup under cold cranking conditions.

Diagnostics include PH pin phase-loss detection (V_PHH1 = 9–11.5 V, V_PHL1 = 0.67–0.92 V), D+ enable logic (V_thD+ = 0.8–1.15 V), and fault-latched DFM open-drain output (f_DFM = 30–400 Hz) synchronized to field switching for ECU telemetry.

Key Specifications

Parameter	Value and Actual Design Meaning
V_reg	14.45 V ±0.15 V at 25 °C; ensures stable battery charging across ambient temperatures (-40 to 125 °C) with -3 mV/°C thermal compensation.
R_DS(on)	130 mΩ max @ 25 °C; enables 5 A continuous field current with <1.5 W conduction loss, reducing thermal stress in compact engine bay layouts.
V_OV	18–22 V D+ disable threshold; prevents regulator activation until alternator output exceeds battery voltage by ≥6 V, avoiding false start-up during cranking.
t_SL	2.5–3.39 s soft attack time; ramps field duty cycle linearly to limit inrush current and suppress electromagnetic interference during alternator excitation.
I_FSC	7–18 A field short-circuit detection threshold; triggers immediate DF shutdown upon ground or battery shorts, protecting MOSFET and wiring harness.
V_HS	≤1.2 V saturation voltage @ 1 A; guarantees reliable high-side relay drive even at low battery voltage (8.5 V min operating supply).
ΔV_load	≤200 mV variation under 0.1–0.9× nominal alternator current; maintains tight regulation during rapid load changes (e.g., HVAC compressor engagement).

Pinout & Package

Package: Bare die (no leadframe or molded package); dimensions referenced to die corner origin per ST DocID029462 Rev 1, Table 2. Mounting requires custom substrate bonding with wire-bond access to 24 copper pads.

Pin/Terminal	Circuit Role	Design Meaning
DF	Low-side field driver output	Drives alternator rotor winding; rated for 11 A DC bond-wire current and 8.5–18 A short-circuit detection.
D+	Regulator enable input	Logic-high (>0.8 V) enables regulation; internal pull-down ensures safe default-off state during ignition off.
A+	Alternator output sense	Monitors stator rectified voltage; used for overvoltage detection (V_OV = 18–22 V) and phase-loss diagnostics.
PH	Phase-loss diagnostic input	Accepts AC waveform from alternator stator; thresholds (V_PHH1/V_PHL1) detect belt break or open brushes.
DFM	Field monitor open-drain output	Delivers PWM signal synchronized to field switching (30–400 Hz); enables ECU to verify field activity without direct DF measurement.
GND	Power and signal reference	Common return for DF, D+, A+, PH, and DFM; 685 × 762 μm pad ensures low-impedance path for high-current transients.

Key Features

Feature	Design Value
Thermal shutdown with hysteresis	Shuts down DF/D+ at 170–200 °C junction temperature; restarts only after ≥2 °C cooldown to prevent thermal cycling damage.
Protected diagnostic lamp driver	Integrates current-limited (0.45–1.5 A) low-side switch with short-circuit protection, eliminating external transistor and resistor.
Load response control	Actively adjusts regulation setpoint during load transients to limit ΔV_load to ≤200 mV, maintaining stability for sensitive infotainment loads.
FSDF pre-excitation mode	Applies 12.5% duty-cycle 348 Hz square wave to DF before full regulation, ensuring reliable alternator startup below 1000 rpm.
Complex fault diagnostics	Detects and latches 5 failure modes (belt break, brush open, field short-to-battery/ground, phase loss) via PH, A+, and DF pins.

Applications

Engine Control Unit Integration

12 V Automotive Charging System

Use Scenario: ECU monitors alternator health and regulates charging via CAN or LIN bus using DFM telemetry and PH/A+ diagnostics.

IC Role / Device Role / Timing Role: Smart regulator providing real-time field status, fault flags, and thermally compensated voltage setpoint to ECU.

Use Value: Enables predictive maintenance (e.g., belt wear detection) and adaptive charging profiles without adding external sensors or logic.

Use Scenario: Regulating battery voltage in gasoline/diesel passenger cars with stop-start functionality and high electrical loads (e.g., ADAS, HVAC).

IC Role / Device Role / Timing Role: Primary voltage controller with soft-start (t_ST = 0 s, t_SL = 2.88 s) and load-response compensation.

Use Value: Maintains 14.45 V ±0.15 V regulation during cranking transients and HVAC compressor engagement, preventing brownouts.

Diagnostic Warning Lamp Control

High-Side Relay Interface

Use Scenario: Driving dashboard warning lamp (e.g., battery symbol) based on detected alternator faults (belt break, field short).

IC Role / Device Role / Timing Role: Protected low-side lamp driver with built-in current limiting and short-circuit detection.

Use Value: Eliminates need for external driver transistor and current-sense resistor, reducing BOM count and PCB area by 3 components.

Use Scenario: Controlling high-side power relays for auxiliary loads (e.g., cooling fans, fuel pumps) using A+ voltage as supply reference.

IC Role / Device Role / Timing Role: High-side driver with 1.2 V saturation voltage and 1.2–3 A current limit, referenced to alternator output.

Use Value: Enables relay control directly from alternator voltage, avoiding separate 12 V rail and improving system efficiency.

Equivalent & Alternatives

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

Alternative Part	Technical Difference	Application Difference	Selection Advice
Infineon TLE8888	Integrated high-side field driver (vs. L9408F's low-side); higher V_reg tolerance (±0.3 V vs. ±0.15 V); no DFM output.	Requires external freewheeling diode; supports higher field currents (10 A) but lacks field activity telemetry for ECU.	Select when high-side topology matches existing alternator design and DFM telemetry is not required.
NXP MC33903	Separate regulator + driver IC pair; lower thermal shutdown threshold (150 °C); no integrated PH phase-loss detection.	Needs external comparator for phase monitoring; suited for cost-sensitive designs where diagnostic depth is reduced.	Select when modular architecture is preferred and phase-loss diagnostics are handled externally.

Compared with TLE8888 and MC33903, the L9408FDIETR offers tighter voltage regulation, integrated DFM telemetry, and comprehensive PH-based diagnostics in a single die - making it optimal for ASIL-B-compliant ECUs requiring field activity visibility and robust fault coverage.

Availability

L9408FDIETR is available at Aetrix Electronics and suitable for automotive ECU integration, 12 V charging system design, and diagnostic warning lamp control requiring stable component supply across extended temperature ranges (-40 to 150 °C junction).

Supply support for L9408FDIETR 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, specializing in automotive-grade analog, power, and microcontroller solutions with AEC-Q100 qualification expertise.

The L9408F belongs to ST's automotive smart power regulator product line, designed specifically for intelligent alternator control in modern ICE and mild-hybrid vehicles with stringent EMI, thermal, and functional safety requirements.

FAQ

Is the L9408FDIETR supplied in a packaged form or as bare die?

The L9408FDIETR is delivered as a bare die (no encapsulation or leadframe), per Table 1 of ST DocID029462 Rev 1. It requires wire-bond mounting onto a custom substrate with thermal and electrical interface design matching ST's recommended pad layout and bonding specifications.

What is the function of the PH pin and how does it detect alternator faults?

The PH pin senses AC voltage from the alternator stator to detect phase loss. When belt break or open brushes occur, PH voltage drops below V_PHH1 (9–11.5 V) while A+ falls below regulated voltage - triggering diagnostic latch and DFM alarm output per Table 6 of the datasheet.

Does the L9408FDIETR support both standard and optional thermal drift versions?

Yes - the standard version (L9408F) has -3 mV/°C drift (14.45 V at 25 °C); an optional version offers -10 mV/°C drift (14.5 V at 25 °C), selectable via metal option during wafer fabrication. The die version shipped as L9408FDIETR corresponds to the standard thermal coefficient.

How is the DFM output used in system-level diagnostics?

The DFM pin outputs an open-drain PWM signal synchronized to field switching (30–400 Hz), allowing the ECU to verify field driver activity without measuring high-current DF directly. Its rise/fall times (0.05–50 μs) and short-circuit current (25–200 mA) are specified for reliable microcontroller GPIO interfacing.

L9408FDIETR Specifications

Product attributes: Attribute value

Manufacturer:: STMicroelectronics

Series:: -

Package/Case:: Die

Packaging:: Tape & Reel (TR)

Product Status:: Active

Applications:: -

Current - Supply:: 50mA

Voltage - Supply:: 8.5V ~ 18V

Operating Temperature:: -40°C ~ 150°C

Grade:: Automotive

Qualification:: AEC-Q100

Mounting Type:: Surface Mount

Supplier Device Package:: Die

L9408FDIETR FAQ

1.How can I place an order for L9408FDIETR through Aetrix?

Please submit a Request for Quotation (RFQ) for L9408FDIETR 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 L9408FDIETR reliable?

The price and inventory of L9408FDIETR are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for L9408FDIETR is usually 5 days.

3.What payment methods are accepted for L9408FDIETR?

We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for L9408FDIETR transactions.

Note: Certain payment methods may incur a processing fee.

4.How is shipping managed for L9408FDIETR?

L9408FDIETR orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.

Once your L9408FDIETR 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 L9408FDIETR?

For technical support, including L9408FDIETR datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your L9408FDIETR requirements.

6.How does Aetrix verify that L9408FDIETR is sourced from the original manufacturer or authorized distributors?

All L9408FDIETR 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 L9408FDIETR meets industry standards.

7.What is the process for return or replacement of L9408FDIETR?

All L9408FDIETR units undergo pre-shipment inspection (PSI). If there is an issue with L9408FDIETR, 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 L9408FDIETR part is unused and in its original packaging.

Return procedure for L9408FDIETR:

1.Submit a request within 90 days.

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

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