CD4066 switch resistance.

Discussion in 'General Electronics Chat' started by TheDag, Feb 2, 2012.

  1. TheDag

    Thread Starter Member

    Jan 1, 2010
    94
    1
    Hi.
    When the IC is alone without nothing, there is still resistance between pin 1 and pin 2.
    how can i disable this resistance?
    its problem because its permanent switch anything Im connecting to it...

    sorry for my bad english.
    Thanks.
     
  2. Audioguru

    New Member

    Dec 20, 2007
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    It is not designed to pass high currents so its on-resistance is high.
    It passes high impedance signals very well.
     
  3. crutschow

    Expert

    Mar 14, 2008
    13,002
    3,232
    As AG stated, it it used to pass high impedance signals, not power. This means the load resistance should be much higher than the switch resistance so the signal is not significantly affected.
     
  4. bertus

    Administrator

    Apr 5, 2008
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    Hello,

    The 4066 needs power to function.
    There are 4 switched each with its own enable line.

    Bertus
     
  5. TheDag

    Thread Starter Member

    Jan 1, 2010
    94
    1
    But how can i set the resistance to 0 ?
    I Need this for this:
    i have simple 9V battery with resistor that power led.
    and between the Battery - and the LED -, I have no connection, here comes the CD4066 that should close the circuit for few seconds and stop...
    but its have contiuous power because this problem...
    sorry my bad english again...
    Please help....
     
  6. Audioguru

    New Member

    Dec 20, 2007
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    Please post your schematic showing how you power and how you turn on and turn off the CD4066.

    Use an ordinary transistor with series base resistor to turn on and turn off an LED.
     
  7. TheDag

    Thread Starter Member

    Jan 1, 2010
    94
    1
    Picture is attached....

    please help
     
  8. bertus

    Administrator

    Apr 5, 2008
    15,647
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    Hello,

    When you look at the datasheet, the ON resistance at 10 Volts powersupply is 180 Ohms.
    This can not be made lower, as it is the typical resistance of the fets inside the 4066.

    Bertus
     
  9. TheDag

    Thread Starter Member

    Jan 1, 2010
    94
    1
    i cannot get the 180 ohm down ??
    what can i do in this case ?
    there is another IC for thing like that ??
    please help....
     
  10. SgtWookie

    Expert

    Jul 17, 2007
    22,182
    1,728
    You might use a power MOSFET instead of the 4066. The source terminal would have to be connected to ground, the gate to the Q output of the 555, and the drain to the remaining connection.

    What is the purpose of this circuit? How much current does the load require?

    What is the purpose of the switch SW1?
     
  11. TheDag

    Thread Starter Member

    Jan 1, 2010
    94
    1
    SWITCH 1 is switch that needs just a connection to power up device.
    i mean, even 0.01 ohm will power up the device... for example..
     
  12. Audioguru

    New Member

    Dec 20, 2007
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    When the 555 timer output goes high to 10V it lights the LED and it turns on the CD4066.
    What is the load for the CD4066?
     
  13. SgtWookie

    Expert

    Jul 17, 2007
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    What is this device that is being powered?

    How much current does it require?
     
  14. TheDag

    Thread Starter Member

    Jan 1, 2010
    94
    1
    its need the lowest current possible to power up, its only close circuit, the voltage is already connected to the device.
     
  15. TheDag

    Thread Starter Member

    Jan 1, 2010
    94
    1
    Please help, its important
     
  16. SgtWookie

    Expert

    Jul 17, 2007
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    You are not giving the information needed to help you, so we can't do anything to help you.
     
  17. TheDag

    Thread Starter Member

    Jan 1, 2010
    94
    1
    OK,
    5v Input, pin 13 and pin 7 measure 3.75v...

    Please help, Thanks.
     
  18. Audioguru

    New Member

    Dec 20, 2007
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    But your schematic shows pin 7 connected to ground so how can it be +3.75V?

    Where is the 5V input? Do you mean that you changed the power supply to +5V?
    With a +5V power supply, a 555 has an output high voltage of +3.75V which is normal and is high enough to turn on the CD4066.

    We do not know the function of your CD4066 because you do not show its switch contacts connected to anything. You also did not say what they will connect to.
     
  19. kubeek

    AAC Fanatic!

    Sep 20, 2005
    4,670
    804
    sn74cb3q3125 from TI has on resistance of 5 ohms, but it is in a teeny-tiny package with 0.625mm pitch.

    But I agree with others that if you posted the rest of the circuit, that is the part that needs to be switched, our help will be much more useful. Without that this is just stabbing in the dark combined with pulling answers from you.
     
  20. TheDag

    Thread Starter Member

    Jan 1, 2010
    94
    1
    Look, its only a bluetooth device, its power up by switch,
    so its just 2 pins that i need to short.
    any ohm will power up the device, that why i need it will not have any ohm...
    sorry for my bad english
     
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