High side switch-Urgent

Discussion in 'General Electronics Chat' started by Daniel_p, May 3, 2010.

  1. Daniel_p

    Thread Starter New Member

    Mar 31, 2010
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    HiCould any body please help me with the following problem?I have a circuit configured as shown in figure1.Network-1 charges thecapacitor from 0V to 350V (part1 in Fig.2) and discharges it(part2 inFig.2)Network-2 charges & discharges the capacitor from 0V to -100V(part 4 inFig2) and vice versa(part 3 in Fig2).During the operation of the network-1(parts 1&2), network-2 must becompletely disconnected from the capacitor and similarly the network-1must be completely disconnected, while the network-2 is working(parts3&4).* charging & discharging period is about 12.5ms(80Hz).* The connection & disconnection of the networks must happen in a veryshort time.*current flows in both directions in the path between networks and thecapacitor.For this reason I selected switch-1 (MOSFET, N-channel) betweennetwork-1 and the capacitor and switch-2(MOSFET, P-channel) betweennetwork-2 and the cap.(for both switches source is connected to thecap.).switch-1 must be on during parts 1&2.It's source is floated and canreach a voltage about +350V.It must be off while network-2 isworking(parts 3&4), where the source experiences a floating voltage from0V to -100V.Also,switch-1 must have a max-Vg>350V during parts 1&2 and min-Vg<-100during parts 3&4.A similar investigation for the switch-2 results in a min-Vg<-100 duringparts 3&4 and max-vg>350v during parts 1&2.How can I realize drivers for these switches?Drivers must be very smalland dissipate ultra-low power.Or any other Idea to realize the switches, except using MOSFETs?I'll be gratefull if any body can help me with this problem!thank you very much in advance

    Fig-1:http://www.4shared.com/photo/alMIR_92/Fig1.html
    Tig-2:http://www.4shared.com/photo/xIqZhkYD/Fig2.html
     
    Last edited: May 3, 2010
  2. mik3

    Senior Member

    Feb 4, 2008
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    The figure is missing.
     
  3. SgtWookie

    Expert

    Jul 17, 2007
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    So, you want tiny drivers that dissipate no power?

    Why don't you just get drivers that are already made, like IRF2110?

    I see nothing that requires urgency, except maybe you posting your circuit diagram. .png format images are preferred, as they are compact, not "lossy", and require no extra software to view.
     
  4. Daniel_p

    Thread Starter New Member

    Mar 31, 2010
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  5. mik3

    Senior Member

    Feb 4, 2008
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  6. Daniel_p

    Thread Starter New Member

    Mar 31, 2010
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    Hi mik3!
    thanks for the reply!
    because of parasitic diodes in MOSFETs I have to use one PMOS and one NMOS transistor!
    from the specification I see just one Voffset for these ICs. may I drive each MOSFET(-100<Vgs<350)with only one IC?
     
  7. mik3

    Senior Member

    Feb 4, 2008
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    Yes, you can drive the n-channel MOSFET with one IC. However, I am not sure about the p-channel MOSFET.

    Do you have the exact circuit?
     
  8. Daniel_p

    Thread Starter New Member

    Mar 31, 2010
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    Hi SgtWookie!
    thanks for the reply!
    Must these ICs be supplied by a large voltage? do you know any good refrence about these ICs in internet?
     
  9. mik3

    Senior Member

    Feb 4, 2008
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    As I see, you don't have much experience with electronics and thus it is dangerous to play around with high voltages. If you are not sure what are you doing call an expert.
     
  10. Daniel_p

    Thread Starter New Member

    Mar 31, 2010
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    I've never used these ICs before!
    But may you please reply this question:
    for the time t1 NMOS must be ON(Vs goes from 0 to 350V) so this IC can help.
    for the time t2 NMOS must be OFF(Vs goes from 0 to -100),so how can I generate a Vgs<0 with this IC(to keep it off)?

    thanx in advance!
     
  11. Daniel_p

    Thread Starter New Member

    Mar 31, 2010
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    Hi SgtWookie!
    do you know any solution for PMOS?
    thanx in advance!
     
  12. Daniel_p

    Thread Starter New Member

    Mar 31, 2010
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    actually I've been working on this circuit since a long time and the experts in this site are my last hope to solve the problem.
    I'll be gratefull if any body can help me.
    thanks a lot1
     
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