Renesas offers a reference solution for Automatic Headlamp On (AHO) / Day Running Light (DRL) capability with the low power RL78/F12 microcontroller (MCU) and intelligent power devices (IPDs) to drive headlamp, tail lamp and tell tale indicators. Automatic Headlamp On (AHO) / Day Running Light (DRL) is developed to keep the headlamp ON during the ignition ON of a vehicle. This reference design complies with upcoming safety standards for two wheelers. The specifications defined for the reference design are based on the inputs from an Indian two wheeler OEM.

The low power automotive RL78/F12 MCU and IPDs are used for the functional requirement. The reference design's unique approach also targets to maintain the overall fuel efficiency even while the electrical load is increased due to the Always ON function of the headlamp. In addition, the design also considers load on the battery during engine idling state.

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Automatic Headlamp On and Day Running Light Diagram

Key Features

  • Automatic Headlamp ON with detection of Bike ON state
  • RPM-based interlock for the headlamp
  • Compatible with 12V and 5V PWM and pulse-based RPM signal
  • PWM-based lamp intensity control for dimming to save power
  • Programmable short circuit and overcurrent protection
  • Load dump protection up to 42V