Setting up a LT3478 current source

Discussion in 'The Projects Forum' started by Domophone, Feb 22, 2016.

  1. Domophone

    Thread Starter Member

    Sep 10, 2013
    42
    0
    Hi Everyone,

    I'm trying to set up an LT3478 current source. The output i'm looking for is between 5 and 25 Volts at 3.5Amps.

    The alternative (because i don't know how i would deal with 20Amps@5V input via PCB) would use a 12V supply and go from 12V to 25V @3.5amps.

    I've made a couple attempts to set it up using LTSpice, but i can't seem to get a boost factor of more than 2 out of the IC. Can anybody shed some light on what i'm missing here?

    In the example LT Spice circuit I've attached, I have set the sense resistor so the output should be 3Amps (0.035 Ohm), however my output never goes past 2.04Amps.If I increase the Input voltage from 12V to 18V, it is suddenly able to output the 3 Amps i'm expecting. I couldn't find this input voltage limitation in the datasheet.

    Thanks in advance for any help/advice!
     
  2. ronv

    AAC Fanatic!

    Nov 12, 2008
    3,281
    1,232
    The current rating for the IC is the input current, not the output current.
     
  3. Domophone

    Thread Starter Member

    Sep 10, 2013
    42
    0
    hahaha, woops. Thanks!
     
  4. ronv

    AAC Fanatic!

    Nov 12, 2008
    3,281
    1,232
    Yes, a bummer. :(
     
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