Binary inputs to select output

Discussion in 'General Electronics Chat' started by Dustin Yoder, Jul 14, 2014.

  1. Dustin Yoder

    Thread Starter New Member

    Jul 14, 2014
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    I'm trying to find a device that will have 5 dc voltage inputs and 32 dc voltage outputs. The 5 inputs would be used to create the binary address of the output to activate. What is this type of device called? So if all inputs had voltage than only output 32 would have voltage. Thanks.
     
  2. ericgibbs

    Senior Member

    Jan 29, 2010
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    hi Dustin,
    This pdf is the 'type' of device, however this 74LS154 is only 5 V TTL in and TTL out, but it will help you identify the type of device you are looking for.

    You could use a TTL input device and add transistors or ULN2804 to get the 32Vout operation.

    E
     
  3. shteii01

    AAC Fanatic!

    Feb 19, 2010
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    Sounds like decoder.
    It is n inputs and 2^n outputs.
    Example:
    n=5 (5 inputs)
    2^5=32 (32 outputs)
     
  4. crutschow

    Expert

    Mar 14, 2008
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    Two types of CMOS decoders that should work are the 16-output CD4514 (active high output) or CD4515 (active low output) which can operate up to 15V. You would use two of them to get 32 outputs. You may need a level-shifter on the inputs and a buffer/driver on the outputs, depending upon the voltages and currents involved, which you did not state.

    Edit: To use two devices controlled by 5 inputs, connect the MSB control bit to an inverter. Also connect the MSB to the Inhibit input of the 1-16 decoder and the inverter output to the Inhibit input of the 16-32 decoder. Connect the other four control bits in parallel to the 4 address bits of the two decoders.
     
    Last edited: Jul 14, 2014
  5. AnalogKid

    Distinguished Member

    Aug 1, 2013
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    There is no single, off the shelf, 5-bit binary decoder. Your best bet is two 4 line to 16 line decoders, ones that have both true and inverting enable inputs. The four least significant input bits go to the 4 adress lines of both chips. The most significant input bit goes to the inverting enable on the chip for outputs 0-15, and the true enable on the other chip for outputs 16-31.

    ak
     
  6. crutschow

    Expert

    Mar 14, 2008
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    Do you have a part number for such a device?
     
  7. shteii01

    AAC Fanatic!

    Feb 19, 2010
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    AnalogKid has a point. I just checked Mouser, I did not see any 32 output lines ICs. The most they list is 24 lines. So for the sake of simplicity two 16 output lines ICs would probably be the best.
     
  8. djsfantasi

    AAC Fanatic!

    Apr 11, 2010
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    I have the same question as Crutschow. I haven't found a 4 to 16 line decoder with both active low and active high enable inputs. IMHO an external gate would be required.
     
  9. ScottWang

    Moderator

    Aug 23, 2012
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    If you concerned about the price then I will recommended to using one 74HC138 and four CD4028.

    And you have to make clarify about - 5 dc voltage inputs and 32 dc voltage outputs?

    Do you mean the 5 inputs are the dc voltage and the 32 outputs also are the dc voltage, if you really mean that then it just the logical problem not the voltage problem.
     
  10. MrCarlos

    Active Member

    Jan 2, 2010
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    Hello Dustin Yoder

    A device with the characteristics you describe does not exist.
    -I'm trying to find a device that will have 5 dc voltage inputs and 32 dc voltage outputs.-

    By the description you mention, in your message, the device may be called:
    32-Channel Analog Multiplexer/Demultiplexer.
    But I found none of 32 channels, only 16.
    Which is the 4067 16-channel analog multiplexer/demultiplexer.
    You could use 2 4067 to get the 32 channels and the 4066 to select one of the 4067.

    But. . . The problem: How much power you're going to drain those 32 volts DC ??
    It's something you have not mentioned so far clarified.
     
  11. AnalogKid

    Distinguished Member

    Aug 1, 2013
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    Note - there is no 32 vlts anywhere in the original question. It's 32 output voltages.

    dj probably is right. I know the 3-to-8 decoders have both enable polarities, but a 24 pin package probaly doesn't have enought pins. You will need a single inverter in addition to the two decoders. If very high speed is not required, an NPN transistor inverter will work.

    ak
     
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