Gating an SCR?

Discussion in 'The Projects Forum' started by Cburg, Jun 18, 2012.

  1. Cburg

    Thread Starter New Member

    May 16, 2012
    13
    1
    Hi Forum,

    I need to trigger the gate of an BT152-600R. Here is the data sheet:

    http://www.nxp.com/documents/data_sheet/BT152_SERIES.pdf

    It says that the maximum gate voltage is 5V. (Vgm). My bus voltage is 340V. The gate current is 3 to 32mA

    Can I just make a voltage divider from the 340V to gnd and feed the center point to the gate through my relay? Maybe use a 68K and a 1KR? That would be 5mA and 5V. Should I go lower on the bottom R?

    I just calculated that that would be 1.65W on the 68K. I guess that's OK.

    What about a pulse transformer driven from the microcontroller with a darlington driving it?

    Thanks for your help!
    Mike
     
  2. Bernard

    AAC Fanatic!

    Aug 7, 2008
    4,172
    397
    A lot depends on how the SCR is used. I would go for pulse transformer driven by BJT , PUT , or UJT. Keep pulse short, less than 100 μs.& be able to drive 50 mA into 20 Ω load, give or take.
     
  3. DickCappels

    Moderator

    Aug 21, 2008
    2,651
    632
    Go with the pulse transformer -that's the way the better ones work. Trying to drive from the 340 V is madness (IMO).
     
  4. Skeebopstop

    Active Member

    Jan 9, 2009
    358
    3
    Yeah, isolation is probably ideal as you can get yourself into trouble high voltage, not only from a safety perspective but also in terms of design guise and noise considerations
     
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