Shop OBEX P1 Docs P2 Docs Learn Events
SX and Darlington transistors — Parallax Forums

SX and Darlington transistors

SteveDSteveD Posts: 64
edited 2006-06-08 16:27 in General Discussion
I would like to use the SX28 to drive a Darlington transistor (TIP 120) capable of supplying 2 amps to a stepper motor.· The motor requires 5 volts to operate.· Would it be wise to use a buffer between the SX and the transistor or is it necessary?· If a buffer is necessary could a NAND gate (SN7400N) be used?
·
Thanks
Steve

Comments

  • Beau SchwabeBeau Schwabe Posts: 6,568
    edited 2006-06-08 16:27
    You don't necessarily need a "buffer" with a NAND gate or equiv, that is what the transistor
    is doing.· What you do need·however is a current limiting resistor from the I/O to the BASE
    of your transistor.
    ·
    Refer to this link for determining the correct current limiting resistor value.
    http://forums.parallax.com/attachment.php?attachmentid=37701
    ·
    Note:In your case, item #1 would be 2 Amps.··For a Darlington transistor, use 1.2V in the
    ····· ·formula·for item #4 in place of the .6V
    ·
    ·
    ·

    ▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
    Beau Schwabe

    IC Layout Engineer
    Parallax, Inc.

    Post Edited (Beau Schwabe (Parallax)) : 6/8/2006 4:30:24 PM GMT
Sign In or Register to comment.