What is the difference between Analog switch and digital switch?

Discussion in 'General Electronics Chat' started by Lukas Park, Apr 27, 2014.

  1. Lukas Park

    Thread Starter New Member

    Apr 27, 2014
    21
    0
    Hi guys.

    I wonder,
    What is the difference between Analog switch and digital switch?

    I know there is some explanation on the webs.
    But I am looking for easier one. like especially why do we choice one of them? reason! Moreover, when I chose one of them, what points should I focus on?

    thanks

    Park.
     
  2. #12

    Expert

    Nov 30, 2010
    16,257
    6,759
    What current and voltage range are you in? It makes a lot of difference and there are a lot of contact methods.
     
  3. crutschow

    Expert

    Mar 14, 2008
    12,991
    3,227
    It depends upon what type of analog or digital signal you are trying to switch.
     
  4. Lukas Park

    Thread Starter New Member

    Apr 27, 2014
    21
    0
    Thanks reply, Above.

    I meant that question is in general&common situation.

    Lukas
     
  5. ErnieM

    AAC Fanatic!

    Apr 24, 2011
    7,386
    1,605
    Unfortunately there is no general answer.

    It is similar to asking if cars run on gas or diesel. It depends on the specific car you are looking at.

    Very generally a logic switch has inputs and outputs that stay at either one of two voltages, while an analog switch the inputs and outputs may vary anywhere between two voltages.

    And welcome to the forums!
     
    Lukas Park likes this.
  6. AnalogKid

    Distinguished Member

    Aug 1, 2013
    4,518
    1,247
    If you are asking about multiplexer ICs, as in an analog mux vs. a logic mux, then there is a clear difference. An analog mux basically is one or more variable resistors per input. These form a T or 1/2 pi attenuator. The off inputs are not truly off as in a broken connection, just turned down really really low. A digital mux recreates the selected input at the output. The input level is examined, and the output level is set accordingly. In this case there is no possible bleed-through or crosstalk from the off inputs to the on input.

    In many cases an analog mux works well with logic signals. A digital mux can not handle analog signals in any form.

    ak
     
    Lukas Park and colinb like this.
  7. alfacliff

    Well-Known Member

    Dec 13, 2013
    2,449
    428
    analog switches are designed to be linear and work over a range of voltages. digital switches only work over a small range of specific voltages and would introduce distortion on an analog signal.
     
    Lukas Park likes this.
  8. crutschow

    Expert

    Mar 14, 2008
    12,991
    3,227
    An analog switch will transmit or block a signal with a range of voltages from 0V to the maximum rating of the switch. This transfer from input to output is essentially linear.

    A digital switch transmits a signal that has only two levels, high and low. The output stays high or low depending whether the input is above or below the input threshold, which is typically at around 1/2 the total digital voltage swing.
     
    Lukas Park likes this.
Loading...