ALT80802 High-Frequency Switching Regulator

Allegro Microsystems' high-frequency switching regulator provides constant output current to drive high-power LEDs

Image of Allegro ALT80802 High-Frequency Switching RegulatorAllegro Microsystems' ALT80802 is a high-frequency switching regulator that provides constant output current to drive high-power LEDs. It integrates a power MOSFET for step-down or inverting buck-boost conversion. The wide input range of 3.8 V to 50 V makes the ALT80802 suitable for a wide range of lighting applications, including those in an automotive input environment. The device rating also enables a simple solution for driving three to four WLEDs in buck-boost configuration, a very common application requirement for automotive lighting applications.

The ALT80802 is designed to aid in EMC/EMI design by frequency dithering, soft freewheel diode turn-off, and well-controlled switch node slew rates. A programmable oscillator allows the ALT80802 to switch outside EMI-sensitive frequency bands such as the AM band.

With current-mode control and simple external compensation, the ALT80802 can achieve fast transient response. The control loop of the ALT80802 is designed for PWM dimming operation to achieve low dimming on-time and low turn-on overshoot. In buck-boost operation, the ALT80802 reduces the current overshoot normally caused by right half plane zero effect during a PWM dimming turn-off transient. Extensive protection features of the ALT80802 include pulse-by-pulse current limit, hiccup mode short-circuit protection, open/short freewheeling diode protection, BOOT open/short voltage protection, VIN undervoltage lockout, and thermal shutdown. It also includes internal clamp to prevent output voltage runaway if output LED string is opened in buck-boost operation.

  • AEC-Q100 qualified
    • Automotive grade; facilitates system level certification
  • Simple operation
    • Same PN can be in buck-boost or buck mode
  • Integrated level shifting
    • Allows ground-referenced enable and fault flag in buck-boost mode
  • PWM dimming via direct logic input or power supply voltage
    • Supports all automotive PWM techniques including single-wire
  • Extensive protection and fault table
    • Robust; does not require extra protection components
  • 3 mm x 3 mm DFN-10 wettable flank exposed pad package
    • Small yet thermally efficient
    • Wettable flank eliminates need for x-ray inspection
  • Supply voltage from 3.8 V to 50 V
    • Handles automotive load dump and cold-crank
    • Can be run in buck mode from a pre-boost supply
  • Supports up to 16 V output in buck-boost mode
    • Addresses automotive market need for 3 to 4 WLED solutions
  • 150 mΩ integrated MOSFET switch
    • Supports up to ~2 A in buck mode and ~750 mA in buck-boost (VIN(MIN) dependent)
  • Programmable switching frequency up to 2.5 MHz, with frequency dithering
    • Designed for low EMC
    • Operation can be above AM band
    • Small solution size

ALT80802 High-Frequency Switching Regulator

ImageManufacturer Part NumberDescriptionTypeTopologyInternal Switch(s)Available QuantityView Details
ALT80802KEJJTR datasheet linkWIDE INPUT VOLTAGE, ADJUSTABLE FALT80802KEJJTRWIDE INPUT VOLTAGE, ADJUSTABLE FDC DC RegulatorStep-Down (Buck), Step-Up (Boost)Yes2990 - Immediate
ALT80802KEJJTR product page link
Published: 2018-11-07