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Is there an inverted version of the ULN2803 or ULN2003 — Parallax Forums

Is there an inverted version of the ULN2803 or ULN2003

T&E EngineerT&E Engineer Posts: 1,396
edited 2012-07-04 00:11 in General Discussion
I am using the ULN2803 on a new 16x16·LED matrix using a positive input into the ULN2803 which then gives a negative input into the Cathodes of my LED matrix.

However on the flip side for the Anodes, I am using 2N3906 PNP transistor / resistor circuits. A negative input goes into the transistor / resistor circuit and provides a positive input to the Anodes of the LED matrix. I would like to not to have to use the transistor / resistors as they are a bit of a pain to solder up. I would like an inverted version of the ULN2803 or something anyone can recommend that provides the drive current for the anodes of·my LED matrix. I also want to keep the chip count down so I don't want to use an inverter chip·AND another driver chip if possible.

So·2 postive driver chips for the anodes and·2·negative driver chips for the cathodes (something like this - if possible).

Any ideas? Comments?

Post Edited (T&E Engineer) : 4/11/2007 5:42:13 PM GMT

Comments

  • T&E EngineerT&E Engineer Posts: 1,396
    edited 2007-04-11 18:31
    I saw the UDN2981 by Allegro Microsystems but I can't find any distributor that sells them (e.g. Jameco, Mouser, etc..)



    Any ideas on something like this 8 channel source driver?
  • tommytommy Posts: 84
    edited 2007-04-11 18:41
    I just went through a "discovery phase" of what open collector devices (LM339) are and do...

    ...and I discovered that they are most efficient when pulling to ground, and have a voltage drop, then, of only .65 volts (with a five volt supply)· When pulling towards the positive side current must flow through a pull-up resistor that you supply, so they are not as efficient in that direction.

    An LM339 is a quad device, not octal like the uln2803, and I forget at the moment·the max current possible, but I imagine it's not·quite as robust as the·2803.

    ·

    Hex inverters (they come in·in a six-pack) might work also...


    tommy·
  • T&E EngineerT&E Engineer Posts: 1,396
    edited 2007-04-11 18:45
    Tommy,

    The LM339 is an analog comparitor not a digital driver or buffer IC for max current out needed for the LED matrix. So this will not work - but I appreciate your input.
  • Paul BakerPaul Baker Posts: 6,351
    edited 2007-04-11 18:49
    You want to search for what is called a high side driver and/or a pnp array (different but accomplish the same thing). The LMD18400 is an example of a high side driver.

    ▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
    Paul Baker
    Propeller Applications Engineer

    Parallax, Inc.
  • T&E EngineerT&E Engineer Posts: 1,396
    edited 2007-04-11 21:51
    Thank you Paul. However, I ordered some samples (UDN2981A-T) from Allegro Microsystems Inc.
  • Bruce BatesBruce Bates Posts: 3,045
    edited 2007-04-11 22:28
    T & E Engineer:

    The Find Chips search engine will give you a number of distributors. Here is a link to it:
    http://www.findchips.com/

    Regards,

    Bruce Bates

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  • T&E EngineerT&E Engineer Posts: 1,396
    edited 2007-04-11 23:16
    This is very nice. I wish I would have known about that sooner. Thanks again!
  • djsdiscodjsdisco Posts: 1
    edited 2012-07-03 02:48
    T&E Engineer wrote: »
    I saw the UDN2981 by Allegro Microsystems but I can't find any distributor that sells them (e.g. Jameco, Mouser, etc..)



    Any ideas on something like this 8 channel source driver?



    the UDN2981 is available from rapid electronics order code 82-2202

    this does work very well for sourcing current instead of sinking it

    http://www.rapidonline.com/Electronic-Components/Udn2981a-8-channel-Power-Driver-82-2202/?sid=0f19c2a4-62e2-4b9d-9383-0ab8bb920c17
  • jmgjmg Posts: 15,183
    edited 2012-07-03 03:58
    Or the TI TLC59213 looks more active, and almost exactly what you asked for.

    It is parallel and darlington (Emitter out / Sourcing drive), but you may be able to find a lower drop, serial variant to cut PCB traces amongst all the LED drivers everyone seems to be rushing to offer ?
  • PJAllenPJAllen Banned Posts: 5,065
    edited 2012-07-03 05:41
    Guys, check the date... it's from more than 5 years ago.
  • RDL2004RDL2004 Posts: 2,554
    edited 2012-07-03 06:01
    A lot of web forums use a message similar to the following. Maybe Parallax could implement this also?

    attachment.php?attachmentid=93931&d=1341320425
    OldThread.jpg
    797 x 106 - 31K
  • jmgjmg Posts: 15,183
    edited 2012-07-03 15:03
    PJ Allen wrote: »
    Guys, check the date... it's from more than 5 years ago.

    hehe, oops, that explains why the TLC59213 was overlooked.... back then, it did not exist yet
  • bsnutbsnut Posts: 521
    edited 2012-07-04 00:11
    jmg wrote: »
    hehe, oops, that explains why the TLC59213 was overlooked.... back then, it did not exist yet
    That's OK I ended up in this really old thread too. It's easy to miss something that hasn't been made.
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