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STMicroelectronics L9911I
- Part No.:
- L9911I
- Manufacturer:
- STMicroelectronics
- Category:
- Special Purpose Regulators
- Package:
- Multiwatt-8 (Straight Leads)
- Datasheet:
-
L9911I.pdf
- Description:
- IC REG AUTO APPL 1OUT 8MULTIWATT
- Quantity:
- Payment:
- Shipping:
Inventory:4,823
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Product details
Overview
L9911I from STMicroelectronics is a monolithic automotive alternator voltage regulator with integrated high-side field driver, diagnostic lamp/relay drivers, thermal and short-circuit protection, and load response control. It regulates battery voltage across 7–18 V input, supports 6- and 8-pole alternators, and delivers up to 5 A field current with <0.6 V saturation at 150 °C. Used in engine control modules for 12 V automotive charging systems.
For engineers reviewing the L9911I datasheet, L9911I pinout, L9911I application, or L9911I equivalent, this page provides verified technical context, validated pin functions, confirmed regulation curves (Vreg-1/Vreg-2), real-world load response timing options (t_ST = 0 s / t_SL = 2.5 s), and authentic alternative part comparisons - all derived from ST's production datasheet DocID10990 Rev 13.
Technical Context
The L9911I implements fixed-frequency PWM field control with phase-sense-based self-start activation (EN-x ≥ 102 Hz) and three-stage soft-start/soft-attack sequencing. Its regulation loop compares sensed B+ voltage against one of four mask-selectable reference curves (Vreg-1 to Vreg-4), each with defined thermal drift (e.g., −4.5 mV/°C for Vreg-1).
Protection includes field short-circuit detection (If_SCTH = 9–18 A), thermal shutdown (Tj-sd = 160–190 °C), overvoltage disable (Vov-p = 18–22 V), and under-voltage diagnosis (Vuv-1 = 7.7–9.5 V). Diagnostics use delayed fault reporting (t-D = 0.2–0.5 s) and phase-loss detection (VPHH1 = 8–10 V, VPHL1 = 0.40 V).
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Regulated Voltage (Vreg-1) | 14.0–14.8 V @ 1400–RPMMAX rpm; −4.5 to −2.5 mV/°C drift - enables stable battery charging across engine speed and temperature. |
| Field Driver Saturation (VF+_sat) | ≤0.6 V @ 4.5 A, 150 °C - minimizes power loss and thermal stress during high-current field excitation. |
| Soft-Start Delay (tST_1) | 0 s (mask-configured) - immediate field ramp-up at engine cranking for fast alternator engagement. |
| Phase Sense Threshold (VPHL1) | 0.40 V - ensures reliable self-start activation even with weak or noisy phase signals at low RPM. |
| Thermal Shutdown (Tj-sd) | 160–190 °C - protects internal drivers from thermal runaway while allowing operation up to 150 °C case temperature. |
| DFM Output Frequency | 125–200 Hz - provides real-time field duty-cycle monitoring for ECU diagnostics without external circuitry. |
| Load Regulation Error (ΔVload) | ≤250 mV @ 5–Inom A - maintains tight voltage tolerance despite large alternator output current swings. |
Pinout & Package
Package: Multiwatt8 (pin 5 GND), thermally enhanced through-hole package with integrated heatsink tab; Rth j-case ≤ 1.5 °C/W.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1 P | Phase sense input | Detects alternator phase voltage to enable self-start and phase-loss diagnosis; threshold VPHL1 = 0.40 V. |
| 2 DFM | Field monitor open-drain output | Provides PWM signal proportional to field duty cycle (125–200 Hz); used for ECU feedback and fault tracing. |
| 3 RES | Reserved | No internal connection; must be left unconnected per datasheet Table 2. |
| 4 L | Diagnostic lamp (low-side) / relay (high-side) driver | Drives warning lamp or relay coil; protected against short circuits (ILSC = 1–2 A, IHSC = 1.2–3 A). |
| 5 GND-case | Power ground / heatsink tab | Primary thermal path and reference node; must be soldered to PCB copper pour for thermal management. |
| 6 RES | Reserved | No internal connection; must be left unconnected per datasheet Table 2. |
| 7 F+ | High-side field driver output | Switches alternator field winding; supports 5 A continuous, protected against short-to-battery/ground. |
| 8 B+ | Sensed battery supply input | Monitors system voltage for regulation and diagnostics; accepts 7–18 V operating range and 40 V transients. |
Key Features
| Feature | Design Value |
|---|---|
| Self-start function | Activates regulation solely from phase signal (≥102 Hz), eliminating need for separate ignition enable line. |
| Load response control | Configurable soft-start (t_ST = 0 s) and soft-attack (t_SL = 2.5 s) prevents voltage overshoot during engine start. |
| Integrated diagnostics | Delayed fault reporting (0.2–0.5 s) and multi-condition detection (belt break, brush wear, field short) reduce false warnings. |
| Field short-circuit protection | Detects F+ short to battery or ground within milliseconds and initiates retry cycle (<25 ms) to preserve driver integrity. |
| Voltage regulation filtering | On-chip filter rejects >5–6 V ripple from long alternator-to-battery cables, eliminating need for external RC network in standard installs. |
Applications
| Engine Control Module (ECM) | 12 V Automotive Charging System |
|---|---|
|
Use Scenario: Regulating alternator output in gasoline/diesel engine control units where space, thermal margin, and diagnostic compliance are critical. IC Role / Device Role / Timing Role: Primary voltage regulator and field driver; performs real-time closed-loop control using phase-sense feedback and B+ monitoring. Use Value: Enables OEM-compliant battery charging across −40 to +150 °C ambient, with built-in ISO 7637-2 transient immunity and diagnostic lamp signaling. |
Use Scenario: Managing charging voltage in passenger vehicles with variable-load electrical systems (e.g., start-stop, ADAS, infotainment). IC Role / Device Role / Timing Role: Multifunction regulator providing field drive, lamp/relay control, and load-response timing (t_ST = 0 s, t_SL = 2.5 s). Use Value: Delivers stable 14.0–14.8 V output with ≤250 mV load regulation error, supporting rapid engine restarts without voltage dip-induced ECU resets. |
| Alternator Smart Regulator Module | Commercial Vehicle Power Management |
|
Use Scenario: Replacing discrete regulator designs in aftermarket or OE alternator assemblies requiring compact, high-reliability integration. IC Role / Device Role / Timing Role: Monolithic replacement for legacy hybrid regulators; integrates control logic, power stage, and diagnostics in single Multiwatt8 package. Use Value: Reduces BOM count by eliminating external MOSFETs, comparators, and protection diodes while maintaining AEC-Q100 alignment via design. |
Use Scenario: Power conditioning in heavy-duty trucks and buses where alternator loads include air compressors, refrigeration, and telematics. IC Role / Device Role / Timing Role: High-current field driver (5 A) with thermal shutdown (160–190 °C) and robust short-circuit protection (11–18 A field threshold). Use Value: Sustains operation under sustained 150 °C case temperatures and 40 V load-dump transients, meeting SAE J1113-11 requirements. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar alternator voltage regulation applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| L9911F | Same die, Multiwatt8 tube-packaged variant; identical electrical specs and pinout; differs only in packing (tube vs. tray). | No functional difference; selected for manual assembly or small-batch prototyping where tube handling is preferred. | Choose L9911F when procurement logistics favor tube packaging or when evaluating same-spec baseline performance. |
| L9911V | Mask-configured for Vreg-2 regulation curve and t_ST = 2 s / t_SL = 9 s timing; different soft-start profile and reference voltage slope (−11.8 mV/°C). | Suited for higher-RPM alternators requiring slower field ramp and tighter high-temp regulation stability. | Select L9911V only if system requires Vreg-2 (14.35–14.65 V) and extended soft-attack timing - not a drop-in replacement for L9911I. |
Compared with L9911F, L9911I offers identical regulation and protection but is optimized for tray-based automated assembly; versus L9911V, it provides faster startup (0 s delay) and lower-temperature drift (−4.5 mV/°C), making it preferable for cold-cranking-sensitive passenger car platforms.
Availability
L9911I is available at Aetrix Electronics and suitable for automotive engine control modules, 12 V charging systems, alternator smart regulator modules, and commercial vehicle power management requiring stable component supply across extended temperature and transient conditions.
Supply support for L9911I 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, designing and manufacturing automotive-grade analog, power, and microcontroller products for mission-critical applications.
The L9911 belongs to ST's automotive power management IC portfolio, engineered specifically for intelligent alternator regulation in 12 V ICE and mild-hybrid vehicles - emphasizing robustness, integrated diagnostics, and AEC-Q100-aligned reliability.
FAQ
What is the self-start activation condition for L9911I?
L9911I activates regulation autonomously when the phase input (Pin 1) exceeds VPHL1 = 0.40 V and its frequency exceeds EN-1 = 102 Hz (at Tj = −40 to 150 °C), enabling engine cranking detection without external enable signals. This behavior is confirmed in Section 1.5 and Table 6 of DocID10990 Rev 13.
Does L9911I require external components for basic operation?
No external components are required for standard installations: the internal voltage-sensing filter handles ripple up to 6 V, and regulation is self-contained. Only an external 2.2 μF capacitor between B+ and GND is needed for very long cable runs (>2 m) to suppress impedance-induced noise, as specified in Section 1.1.
How does L9911I protect against field driver short circuits?
L9911I detects field short circuits via If_SCTH threshold (9–18 A depending on junction temperature) and disables F+ within milliseconds. It then enters a retry cycle (<25 ms) in switching mode - not linear mode - preserving driver lifetime while maintaining diagnostic visibility, per Figure 15 and Table 10.
Can L9911I be used in 24 V commercial vehicle systems?
No - L9911I is rated for 7–18 V operating supply (B+) and 40 V transient survival (load dump), making it suitable only for 12 V automotive systems. For 24 V applications, ST recommends the L9912 series, which features 24 V nominal operation and higher absolute maximum ratings per ST's product segmentation.
L9911I 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
L9911I FAQ
1.How can I place an order for L9911I through Aetrix?
Please submit a Request for Quotation (RFQ) for L9911I 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 L9911I reliable?
The price and inventory of L9911I are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for L9911I is usually 5 days.
3.What payment methods are accepted for L9911I?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for L9911I transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for L9911I?
L9911I orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your L9911I 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 L9911I?
For technical support, including L9911I datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your L9911I requirements.
6.How does Aetrix verify that L9911I is sourced from the original manufacturer or authorized distributors?
All L9911I 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 L9911I meets industry standards.
7.What is the process for return or replacement of L9911I?
All L9911I units undergo pre-shipment inspection (PSI). If there is an issue with L9911I, 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 L9911I part is unused and in its original packaging.
Return procedure for L9911I:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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