STMicroelectronics has launched an L9918 auto alternator regulator with upgraded features that ensure security and stability for 12V car electrical systems. The regulator has an MOSFET that supplies an excitation current for the alternator, as well as a diode for freewheeling to manage the current flowing through the rotor when excitation is off. Closed loop operation using the control of load (LRC) with return LRC keeps a constant voltage when the vehicle’s power consumption changes. The excitation MOSFET can supply an up-to 13 A to the coil which is higher than what regulators that are available and improves its ability to respond to changing demand. Furthermore, with the most recent manufacturing process technology this MOSFET offers superior RDS(on) and thus reduces the power loss while increasing efficiency.
With an integrated non-volatile memory (NVM) the L9918 lets customers set parameters such as the voltage set point as well as alternator characteristics. It can be utilized with alternators having up to nine pole-pairs offering greater adaptability than many other regulators to handle many different charging needs. Also integrating a Local Interconnect Network (LIN) bus interface, the L9918 is easily connected to the vehicle electrical/electronic infrastructure to be managed by an external electronic control unit (ECU). The ECU controls settings, including the voltage to be targeted and also analyzes diagnostic and status information. The safety and failsafe functions that are part of L9918 include auto-start activation via the phase signal. It also keeps the voltage of the alternator set at a specific point if the LIN connection is cut off due to any reason.
The regulator returns control back to the ECU after communications are restored. Overcurrent protection, current limitation and thermal protection are included, as is thermal compensation that adjusts the voltage of the target when the temperature of the system fluctuates. In compliance with the VDA (Verband of Automobilindustrie) LIN Alternator Regulator specification The L9918 is AEC-Q100 certified, ISO26262 compliant, and ASIL-B capable of use in functional safety systems. The L9918 is currently in production now and being distributed to major customers around the world.