45-V 2.3-A LED driver for boost, buck, or buck-boost high-current applications

Date
08/23/2012

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Offers maximum TJ of 150 °C in QFN package

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The LT3518HUF operates from 3 to 30 V supplies and can provide 2.3 A to LEDs in high-ambient-temperature applicaitons.

Linear Technology has announced the H-grade version of the LT3518. The LT3518 is a 45-V high-side current-sense DC-DC converter designed to drive high-current LEDs at constant current. Its 3- to 30-V input-voltage range with transient protection to 40 V makes the LT3518 well suited for a wide variety of applications including automotive, industrial, and architectural lighting, which are subject to high ambient temperatures. The H-grade version operates with a TJ (junction temperature) up to 150 °C, compared to the E- and I-grade versions' 125 °C maximum TJ. All electrical specifications are identical for the E-, I-, and H-grade devices. The LT3518 can drive up to eight 300-mA white LEDs from a nominal 12-V input, making it well suited for applications such as automotive display backlighting. The LT3518 senses output current at the high side of the LED, enabling buck, buck-boost, or boost configurations. The LED driver, available in a 4 x 4 mm QFN package, can deliver efficiencies up to 90% in boost mode. The LT3518 offers True Color PWM dimming, delivering constant LED color with dimming ranges of up to 3,000:1. For less demanding dimming requirements, applications can use the CNTRL pin to offer 10:1 analog dimming. Its fixed frequency, current-mode architecture ensures stable operation over a wide range of supply and output voltages. A frequency adjust pin enables the user to program the frequency between 250 kHz and 2.5 MHz to optimize efficiency while minimizing external component size. The LT3518HUF is available from stock in 16-pin QFN package. Priced starting at $3.79 each in 1,000-piece quantities. Summary of Features: LT3518H

  • 150 °C maximum junction temperature
  • 3,000:1 True Color PWM™ dimming ratio
  • 2.3-A, 45-V internal switch
  • 100-mV high-side current sense
  • Open LED protection
  • Adjustable frequency: 250 kHz to 2.5 MHz
  • Wide input-voltage range:
    • Operation from 3 to 30 V
    • Transient protection to 40 V
  • Operates in boost, buck, and buck-boost modes
  • Gate driver for PMOS LED disconnect
  • Constant-current and constant-voltage regulation
  • CTRL pin provides 10:1 analog dimming
  • Low shutdown current: < 1 μA
  • 4 × 4 mm 16-pin QFN package
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