Trying to find the pin number layout of an LTM8494G alphanumeric display

Discussion in 'General Electronics Chat' started by programmer6502, Jun 12, 2015.

  1. programmer6502

    Thread Starter Member

    Feb 1, 2014
    126
    6
    Hi,

    I went to an electronics surplus store yesterday and made some scores while attempting to make sure that the parts I purchased were known so I didn't have problems. However, time became short and I didn't have time to research this cool double digit alphanumeric display:

    [​IMG]
    [​IMG]

    As you might be able to make out from the pic showing the bottom of the display, it has a built in driver which I'm stoked about, but the full model number of this particular display won't come up online. I did find something similar here on Digi-Key though (which includes the datasheet in the link).

    Now the problem I'm having here (assuming that my display works the same as the one on Digi-key), what's the pin number layout of this thing? The datasheet on Digi-Key has a pinout, but no layout giving you a clue about how these pins are numbered! I've never seen a datasheet like that! So if anyone has an idea of how these pins are numbered (and frankly, a specific pinout for this display) that would be awesome!

    Thanks!
     
  2. MrChips

    Moderator

    Oct 2, 2009
    12,440
    3,361
    You can determine the pinout without having the datasheet by using an ohmmeter or a simple power supply with a current limiting resistor (1kΩ for 3V to 12V supply).

    Here is the datasheet for LTP3784G as an example.
     
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  3. programmer6502

    Thread Starter Member

    Feb 1, 2014
    126
    6
    Since mine has a built in serial driver and I can't connect to particular segments with an ohm meter, would it still be possible to decipher the pins?

    I believe it's similar to this LTM-8647AHR
     
  4. upand_at_them

    Active Member

    May 15, 2010
    246
    29
    With display orientated for proper viewing pin 1 is lower left corner. Increment counter-clockwise.
     
  5. programmer6502

    Thread Starter Member

    Feb 1, 2014
    126
    6
    That's what I was wondering, thanks! If it still works, it'll be a convenient and useful little display. I like the idea of simply clocking in 35-bits of display data (according to the LTM-8647AHR datasheet) for the characters I desire instead of having a bunch of messy external circuitry!
     
  6. ian field

    Distinguished Member

    Oct 27, 2012
    4,415
    784
    NS used to do a shift register chip specifically designed for clocking in bits to drive displays. But that was back in the days of the old COP (Calculator Operating Principle) front panel micros for TVs and the like.
     
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  7. programmer6502

    Thread Starter Member

    Feb 1, 2014
    126
    6
    I'm going to write some code on my microcontroller to get this thing going, but the LTM-8647AHR datasheet is also unclear as to whether the data_enable line is active high or low. In fact, it says nothing about it at all! Just a timing diagram that shows it.

    Any guesses?

    LTM-8647AHR datasheet
     
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