Design Win



Car headlights, taillights and flashers reliability represent a key factor for car driver and pedestrian safety: ST offers a wide selection of high- and low-side drivers to turn interior, front and rear lights from higher power “front beam” lamp to low power loads as indicators and back lights.

Target Applications

  • Front LED lighting systems
    • Low Beam
    • High Beam
    • Daytime Running Light
    • Turn Indicator
    • Position, Side and Fog Light

  • 主要产品优势

    The L99LD21 is a flexible LED driver, which is specifically designed for the control of two independent high brightness LED strings for automotive front lighting applications. It consists of a high efficiency monolithic boost controller and a dual buck converter.

    L99LD21 key benefits:

    • ST SPI communication v4.1
    • 5.5 to 24 V Operating battery voltage range
    • Load dump protected
    • QFN40L 6x6 (wettable flanks) with exposed pad
    • Low standby current
    •  Boost Regulator
      • with fixed frequency architecture and programmable by SPI, with input current limitation, overvoltage protection (OVP) and constant voltage control
    • Buck regulator
      • Lossless current sensing without need of external components, very accurate LED current setting programming inductor's peak current and peak-to-peak current ripple
      • Adjustable peak current by SPI and adjustable current ripple by SPI
      • Integrated PWM generation unit with 10-bit resolution and phase shift
    • LED voltage digital feedback through SPI
    • 2 soldered L99LD21 flexible LED drivers
    • Board size 100 x 55 mm
    • Two extension headers (2 x 36 pin - 100 mil) for quick connection to SPC560B-DIS discovery board
    • Controllable by dedicated GUI available on
    •  Free ready to run application firmware available on, to support quick evaluation and development