implement relay matrix using uln2003

Discussion in 'Digital Circuit Design' started by kooldude, Feb 27, 2018.

  1. kooldude

    Thread Starter New Member

    Feb 15, 2018
    13
    0
    how to implement relay matrix using uln2003 without using any gate?Its urgent.Waiting for your response..
     
  2. KeepItSimpleStupid

    Distinguished Member

    Mar 4, 2014
    2,869
    504
    You really want a high side driver (e.g. x) and a ULN200x (e.g. y) for the low side driver.
     
  3. AnalogKid

    AAC Fanatic!

    Aug 1, 2013
    7,045
    1,994
    That cannot be done. The ULN2003 is a low side driver *only*. To form a switching matrix you need both low and high side drivers.

    Your question is very poor and has almost no details needed to discuss a solution.
    What is the matrix switching?
    What is controlling the matrix?
    What is the matrix?

    ak
     
  4. kooldude

    Thread Starter New Member

    Feb 15, 2018
    13
    0
    basically there will be one gpio expander 8+8 is there with that we will make 8*8 relay matrix....and only one relay need to be selected..
     
  5. KeepItSimpleStupid

    Distinguished Member

    Mar 4, 2014
    2,869
    504
    We can;t pick any parts because there is no design information. But, you need high and low side drivers.
     
  6. AnalogKid

    AAC Fanatic!

    Aug 1, 2013
    7,045
    1,994
    ak
     
  7. kooldude

    Thread Starter New Member

    Feb 15, 2018
    13
    0
    ok..do u have design or any document which can explain this?how it works and how it can be implemented?
     
  8. dendad

    Well-Known Member

    Feb 20, 2016
    2,028
    522
    Do you have any information that can help us help you?
    Controller?
    What sort of relay? --- Relay coil voltage and current.
    Why a matrix and not just a number of port expanders? --- That would allow any relays to be operated, not just one at a time.
     
  9. KeepItSimpleStupid

    Distinguished Member

    Mar 4, 2014
    2,869
    504
  10. AnalogKid

    AAC Fanatic!

    Aug 1, 2013
    7,045
    1,994
    Besides the ULN2003 low side drivers, you need some kind of high side driver.

    Is this homework or a school project?
    Why are you not allowed to use gates?
    Why must you use only ULN2003's?
    Why do you have two threads on the same topic?

    ak
     
  11. kooldude

    Thread Starter New Member

    Feb 15, 2018
    13
    0
    now i am using two drivers one for high side and another for low side..as you all have suggested
     
  12. kooldude

    Thread Starter New Member

    Feb 15, 2018
    13
    0
    due to some network issue two threads were made
     
  13. AnalogKid

    AAC Fanatic!

    Aug 1, 2013
    7,045
    1,994
    Is it working?
    What are the driver part numbers?
    What is the voltage for the relays?
    What is the relay part number?

    ak
     
  14. ian field

    AAC Fanatic!

    Oct 27, 2012
    6,205
    1,117
    There are crosspoint arrays used in telecoms, but I doubt they'll handle the current draw of relay coils.
     
  15. kooldude

    Thread Starter New Member

    Feb 15, 2018
    13
    0
    Why do we need one high side driver and low side driver in the relay matrix?
     
  16. dendad

    Well-Known Member

    Feb 20, 2016
    2,028
    522
    In a matrix, both ends are switched, so a high side and a low side driver are needed.
     
  17. kooldude

    Thread Starter New Member

    Feb 15, 2018
    13
    0
    can you give detailed explaination more on this?
     
  18. dendad

    Well-Known Member

    Feb 20, 2016
    2,028
    522
    LED_Matrix.jpg
    S1 on (high side) and S4 on, (low side) lights D1.
    Other switch combinations for the other LEDs.
    Generally, only one LED at a time in this particular example.
    The number of high side and low side switches can be increased to end up with n(highside) x n(lowside) combinations.
    If you just had high side switches in the above example, only 3 LEDs could be independently driven.
    Adding the extra 3 low side switches allows 9 LEDs.

    If you really want to get a bit confused, Google "Charlieplexing" ;)
     
  19. AnalogKid

    AAC Fanatic!

    Aug 1, 2013
    7,045
    1,994
    It is a consequence of a design tradeoff. If you have 48 relays you want to control, one way to do that is tie one end of all of the relays to V+, and have 48 driver transistors (in 7 ULN2003's) , one for each relay. You can turn on any of the relays in any combinations but that's a lot of parts.

    If you arrange the relays in a 6 x 8 matrix, two things change. One is that you now can turn on only one relay at a time. The other is that you need only 14 drivers, one for each row and column. BUT, the tradeoff is that the row drivers and column drivers must be different, because on is sourcing current *into* the relay coil and one is sinking current *out of* the relay coil. From the point of view of a transistor, those are two different current directions, and the "semi" in semiconductor means current can flow only one direction in a device.

    ak
     
Loading...