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Advanced VDA-compliant LIN Alternator Regulator for 12V Vehicle Electrical Systems

L9918 Automotive Alternator Regulator
L9918 Automotive Alternator Regulator

STMicroelectronics has introduced the L9918 automotive alternator regulator with enhanced features to ensure the stability of 12V vehicle electrical systems. This regulator is AEC-Q 100 qualified, ISO26262 compliant, and ASIL-B ready for use in functional-safety systems. With integrated nonvolatile memory (NVM), the L9918 regulator allows customers to program parameters including the voltage set point and alternator characteristics. It can be used with alternators that have up to nine pole-pairs, delivering more flexibility than other regulators to address a wide variety of charging applications.


This regulator contains a MOSFET to deliver alternator excitation current and a freewheeling diode to handle the rotor current when excitation is turned off. Closed-loop operation with load response control (LRC) and return LRC maintains a consistent voltage as the vehicle’s overall power demand changes continuously. Integrating a Local Interconnect Network (LIN) bus interface, it is easily connected to the vehicle electrical/electronic infrastructure to be managed by an external electronic control unit (ECU). The ECU commands settings including the target voltage and reads status and diagnostic information.


Safety and failsafe features of this regulator include self-start activation by phase signal, which independently maintains the alternator voltage set point if the LIN connection is lost for any reason. The regulator returns control to the ECU when communication is restored. Current limitation, overcurrent protection, and thermal protection are also built-in, as well as thermal compensation that automatically adjusts the target voltage as the system temperature changes.



  • AEC-Q100 qualified

  • Closed loop voltage control

  • Regulated voltage with thermal compensation function

  • High side excitation driver with internal freewheeling circuit

  • Load response control (LRC) and Return LRC

  • Self-start activation by phase signal

  • Current limitation and overcurrent protection

  • Thermal protection

  • Physical Layer compliant with LIN 2.2A spec.

  • Data Link Layer compliant with LIN 1.3, 2.1, 2.2 and 2.2A specification

  • 13 sets of LIN frames selectable

  • Configurable parameters (see NVM parameter table A1)

  • Configurable for 5, 6, 7, 8 or 9 pole pair alternator

  • Compliant to VDA LIN-Generator-Regulator specification

  • Full ISO26262 compliant, ASIL-B systems ready

  • Available as Bare die as well as in PENTAWATT In Line (TO220-5) package



  • Automotive chargers

  • 12V vehicle electrical systems


Availability & Pricing

The L9918 regulator is now in production and is available as bare die and in a PENTAWATT inline TO220-5 package, prices start from $6.12 for orders of 1000 pieces.

Component Datasheet

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