LT3598 Demo Board

Discussion in 'General Electronics Chat' started by ELECTRONERD, Aug 7, 2009.

  1. ELECTRONERD

    Thread Starter Senior Member

    May 26, 2009
    1,146
    16
    Greetings,

    I just received the LT3598 demo board from Linear Technology and I have a few questions. Below you'll find the LT3598 datasheet and also the Demo circuit quick start guide.

    http://cds.linear.com/docs/Datasheet/3598fa.pdf

    http://internal.linear.com/demo/dc1285A.pdf

    In the Quick Start Guide, they say to connect the PWM pin to VIN. I'm wondering how I can adjust the PWM? In the schematic if I put another resistor from the CTRL pin to ground it would form a voltage divider. Thus, varying voltage. Or, would I put a resistor from the PWM pin to ground? Would this adjust the PWM? Also, what are the OPENLED, and SYNC pins for?

    Thanks!
     
  2. Ron H

    AAC Fanatic!

    Apr 14, 2005
    7,050
    657
    The quickstart guide says
    The PWM signal cannot be a DC level, unless you want the LEDs full on or full off. You have to provide a variable duty cycle pulse waveform (PWM) to vary the LED brightness. You can generate this with a circuit such as SgtWookie's Simple PWM Circuit.
    From the datasheet:
     
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