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Confused about the AM26LS32ACN

Discussion in 'General Electronics Discussion' started by zytrahus, May 3, 2013.

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  1. zytrahus

    zytrahus

    5
    0
    May 3, 2013
    Hi, I'm new here :)
    I am trying to convert the sub-outputs (A high, low, B high, low) of an encoder into standard Channel A and B quadrature encoder signals.
    My encoder is a Maxon #225773. Maxon recommends the differential Line receiver AM26LS32.

    So I am looking at this datasheet and actually did some ONE test already but my signals are not they should be.

    Here's the datasheet for the line receiver: http://www.ti.com/lit/ds/symlink/am26ls32a.pdf

    I am using 2 of the 4 comparators in the chip and I am just completely confused about setting up Pin 4 and Pin 12.

    in page 2 of the PDF, there is a nice table that is supposed to help me setting them up but honestly it doesn't help me at all.


    Could anyone point me in the right direction?


    Here's what I tried. I didn't have the complete datasheet and there was mention to put Pin4 to Low (ground) and Pin12 to High (Vcc) in order to activate the high impendance output. That datasheet didn't have any other information and figured I'd try this mode which didn't work out, the output signal wasn't recognized by my controller.

    Note that my controller is designed to read the output of an HEDS9100 which is an optical encoder with built in line receivers. My new encoder doesn't have these line receivers and I need to do internally before I send the output to the controller.


    Based on this datasheet, and if I had to guess I would try and put Pin4 to High and would let Pin12 floating. But I am afraid of damaging my controller and I have no practical way to test that other than trial and error...

    Basically any advice here would be really appreciated.

    Thanks
    Z.
     
  2. Rleo6965

    Rleo6965

    585
    9
    Jan 22, 2012
    Pin 4 was an active HIGH ( 5V) enable signal and pin 12 was an active LOW ( 0V ). So, if your not controlling this 2 input signal and you want the AM26LS32 always enabled. Just connect pin4 to 5V and pin12 to gnd (0V). Output voltage of AM26LS32 was almost same voltage of its supply voltage. So, if your controller VCC (5V) was same with AM26LS32 VCC then it would not be a problem and will not damage input of controller.

    Try it and let us know.
     
    Last edited: May 4, 2013
  3. zytrahus

    zytrahus

    5
    0
    May 3, 2013
    thanks for the response.

    I play with it yesterday and was able to get working by connecting pin 12 to the ground and by letting pin 4 Not Connected.

    Is this acceptable to you?

    I had a hard time interpreting this datasheet and doing this is what made the most sense to me.
     
  4. Rleo6965

    Rleo6965

    585
    9
    Jan 22, 2012
    Pin 4 must connected to +5V to avoid intermittent problem. Unless you need to disable and enable AM26LS32 and use pin 4.

    The reason that AM26LS32 have 2 control pin (4 and 12 ) so that you can use any available control signal from your circuit to enable/ disable it. If you have active high signal. Use pin 4 and connect pin 12 to gnd. If you have active Low signal. Connect pin 4 to +5V and use pin 12 as control pin.
     
  5. zytrahus

    zytrahus

    5
    0
    May 3, 2013
    Thank you but I am afraid this goes above my understanding of how comparators actually work :(
     
  6. Rleo6965

    Rleo6965

    585
    9
    Jan 22, 2012
    Differential comparator have 2 inputs. 1 for non-inverting signal and another 1 inverting signal. This 2 input accept combination of high input around 3V and Low input signal and in combination will be equal to 6V. This combination opposing signal will result high output of comparator and absence of this 2 signal will result Low output signal.

    . Differential receiver always work with differential transmitter AM26LS31 or other similar transmitter such as HEDS9100.

    In my previous job as MICROS POS Service Engineer. Almost our RS422 network communication circuit were using AM26LS32 and AM26LS31. Because we need long wire communication between PC Server, POS and printers. :)
     

    Attached Files:

    Last edited: May 4, 2013
  7. zytrahus

    zytrahus

    5
    0
    May 3, 2013
    Hi, thanks for your response.

    Here's the datasheet of my encoder.

    How would you connect A high low, B high low and both pin 4 and 12?
     
  8. Rleo6965

    Rleo6965

    585
    9
    Jan 22, 2012
    Just connect pin4 to 5V and pin12 to gnd (0V). That's it.
     
  9. zytrahus

    zytrahus

    5
    0
    May 3, 2013
    thanks, I tried and it also works that way. I think I am going to go with this solution, I hate having floating inputs.

    thanks again!
     
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