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CAT3644

4-Channel Ultra High Efficiency Quad-Mode™ LED Driver



Features Description Applications

FEATURES
  • High efficiency 1.33x charge pump
  • Quad-mode charge pump: 1x, 1.33x, 1.5x, 2x
  • Drives up to 4 LEDs at 25mA each
  • 1-wire EZDim™ LED current programming
  • Power efficiency up to 92%
  • Low noise input ripple in all modes
  • “Zero” current shutdown mode
  • Soft start and current limiting
  • Short circuit protection
  • Thermal shutdown protection
  • 3mm x 3mm, 16-pad TQFN package
DESCRIPTION

The CAT3644 is a high efficiency Quad-Mode™ fractional charge pump that can drive up to four LEDs programmable by a one wire digital interface. The inclusion of a 1.33x fractional charge pump mode increases device efficiency by up to 10% over traditional 1.5x charge pumps with no added external capacitors.

Low noise input ripple is achieved by operating at a constant switching frequency which allows the use of small external ceramic capacitors. The multi-fractional charge pump supports a wide range of input voltages from 2.5V to 5.5V.

The EN/DIM logic input functions as a chip enable and a digital dimming interface for current setting of all LEDs. Six different current ratios are available via the interface.

The device is available in the tiny 16-pad TQFN 3mm x 3mm package with a max height of 0.8mm.

Catalyst Semiconductor's Quad-Mode™ 1.33x charge pump switching architecture is patented.

TYPICAL APPLICATION

CAT3643 typical application

APPLICATIONS
  • LCD Display Backlight
  • Cellular Phones
  • Digital Still Cameras
  • Handheld Devices
 
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Tape and Reel info

LED Power-Management for Backlighting

Electronic Design Magazine
September 2006

PRESS  RELEASE
Catalyst Semiconductor Debuts World's Smallest, Highest Efficiency Fractional Charge Pump (February 8, 2007)
         
Hot Tips
  • For a six channel device with versatile programming ability, see the Quad-Mode™ LED driver CAT3636
  • For the Quad-Mode™ three channel device, see the CAT3643
  • For 32 dimming levels see the CAT3648
 
3644