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totem pole mostfet pair assistance — Parallax Forums

totem pole mostfet pair assistance

nick bernardnick bernard Posts: 329
edited 2005-01-18 14:54 in General Discussion
HAIL YOU GUYS....
can anyone recommend a good pair of TO-92 case mosfets that i can use in a totem pole driver circuit?

i've traditionally used 2n7000's for misc mosfet needs and i need a good match for the pole

that would be the rox

nick B

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Comments

  • Mark GMark G Posts: 11
    edited 2005-01-17 23:28
    You can check out International rectifier www.Irf.com....

    The last totem pole I worked with was over a year ago and used a IRF230 & IRF5210 (TO-3 & To-220 respectively).

    One thing to be aware of is that if your gate drive signal is slow to change or weak you may have both FETs conduct at the same time.. Pretty obvious if this happens as you will have very hot parts (& Possibly smoke). I had this problem when applying the ouput of a MC14050 inverter through s 2.2 K resistor to the gate... Ended up adding a 200ohm pull up to the gate as well which solved much of the problem.
  • Paul BakerPaul Baker Posts: 6,351
    edited 2005-01-18 03:25
    I could be wrong, but there may be some matched pairs available in a single package (dunno if they can support enough current for your needs, and won't be in a to-92). I'll check tomorrow and let you know.

    Paul
  • Paul BakerPaul Baker Posts: 6,351
    edited 2005-01-18 14:54
    Ok, here are some part numbers for dual mosfets (one pchannel, one nchannel) in a single package, they are digikey part numbers which contain the manufactuer number within them, search thier website for the actual MP#:

    On Semiconductor, MMDF2C03HDR2OSCT, 8-SOIC $12.35 (most expensive but only one to specifically say complimentary)
    Toshiba, TPC8403CT, SOP-8, $.88
    ··········· TPCF8402CT, VS-8, $.92
    International Rectifier, too many to list check this catalog page: http://dkc3.digikey.com/PDF/T051/0683.pdf
    ST, 497-3232-1, 8-SOIC, $2.10
    Diodes Incorperated, BSS8402DWDICT, SOT-363, $5.94

    There are also matched npn/pnp parts but I didnt list them since your schematic specifies mosfet.
    If you need through hole, digikey also sells smd to through hole adapters, let me know if you have a problem finding them and I'll point you in the right place.

    Paul
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