pos&neg rails switching

Discussion in 'General Electronics Chat' started by masa6614, Feb 15, 2009.

  1. masa6614

    Thread Starter Active Member

    Nov 9, 2008
    49
    0
    Hi,
    I've come across a HV swithing problem, I wanna switch open and close two power rails, +400V and -400V simulataneously. Now i know the simplest solution would seem to be a DPST relay, but looking at the voltage/current requirements, they get very expensive. So seems the simplest way would be to switch some HV mosfets or IGBT's, but the problem seems to be the highside drivers for these guys all seem to use a bootstrapping method that won't allow them to have a 100% duty cycle and be continuously on. i came across this appnote from intnl rect:
    http://www.irf.com/technical-info/designtp/dt92-4.pdf
    and that seems to be the solution, adding a charge pump yourself using a 555 timer and some Rs, Cs, and diodes. Now I seemed confused on whether i can implement this on the negative rail as well, i want to basically mirror the circuit, but its that connection on the bottom of the load and the 555 circuit using a 100k that i'm not sure how to do on the negative rail? any help is greatly appreciated.
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  2. masa6614

    Thread Starter Active Member

    Nov 9, 2008
    49
    0
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