Datasheet Linear Technology LTC3205EUF#TRPBF

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  White LED Driver Minimizes Space, Maximizes Efficiency and Flexibility &mdash LT Journal
  PDF, 137 Kb, File published: Dec 1, 2003
  Extract from the document

  DESIGN FEATURES White LED Driver Minimizes Space,
  Maximizes Efficiency and Flexibility
  by Steven Martin Introduction White LEDs are the LCD backlight of
  choice for portable equipment due to
  their small profile, exceptional ruggedness and high luminosity. Li-Ion
  batteries, also rugged and small, are
  the popular power choice for the same
  portable equipment. The white LEDs
  have a nominal forward voltage between 3V and 4V and a Li-Ion battery
  has a nominal voltage of 3.6V, thus
  requiring circuitry to step-up the Li-Ion battery’s voltage. The problem is,
  stepping up tends to reduce efficiency,
  which in turn reduces battery life. The
  LTC3205 solves this problem by powering up in direct-connect mode rather
  than step up mode. Once powered up,
  it uses a dropout detector for each
  white LED to determine if any are running out of drive. As the first white LED
  just begins to lose current, the chip automatically engages a very powerful 2:
  C1+ C1– C2+ C2– 5 4 6 3 800kHz
  OSCILLATOR 25 PGND
  15 CPO VIN 16
  1:1 AND 2:3 CHARGE PUMP –
  + ENABLECP + …

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Manufacturer's Classification

• Power Management > Inductorless (Charge Pump) DC/DC Converters > Inductorless (Charge Pump) LED Drivers

Other Names:

LTC3205EUFTRPBF, LTC3205EUF TRPBF