• State TI Thinks Resolved
  • Locked Locked
  • Replies 3 replies
  • Answers 1 answer
  • Subscribers 16 subscribers
  • Views 910 views
  • Users 0 members are here
Support feedback
Options
Options
Similar topics

This thread has been locked.

If you have a related question, please click the "Ask a related question" button in the top right corner. The newly created question will be automatically linked to this question.

Original question:

CD4066B: whether the CD4066B can support +-8v input signal

CD4066B: How to set up control pin for negative application?

Dylan Zheng
Intellectual 1415 points
Part Number: CD4066B
Other Parts Discussed in Thread: TMUX1511, CD74HC4316

Hi team,

Does  CD4066B support below requirement?

  1.  input voltage: -2.5mV-22.5mV
  2. VDD=5V VEE=-5V
  3. Which voltage  should be applied in control pin to open or close the switches?

Best regards,

Dylan

  • 0
    TI__Expert 5660 points

    Hello Dylan,

    CD4066B does support a +/- 5V supply signal (VDD = 5V, VSS = -5V). With this supply voltage, the signal swing may be up to +/-5V (10 Vpp). 

    Since your I/O voltage range is -2.5mV to 22.5mV, the switch supports this operation at your supply voltages.

    For the control pin input voltages, you're looking for the VIHC and VILC specifications in the datasheet, found in the Electrical Characteristics section. Take a look at the screen captures from the datasheet:

    This means that the control signal voltage must be less than 1V to trigger a "Low" and the voltage must be at least 3.5V to trigger a "High". These characteristics are specific to your positive voltage supply, VDD = 5V. 

    Thanks for your question! What is your application and end equipment? I'd like to confirm that you actually will need a negative I/O voltage frequently. Since this negative voltage is so close to 0V, we may be able to find a better device for your application that has features such as 1.8V control logic input levels and powered-off protection. Take a look at TMUX1511 and let me know your application where this negative I/O voltage is necessary.

    Best regards,
    Kate

  • 0 in reply to Kate Dickson
    TI__Intellectual 1415 points

    Hi Kate,

    The CD4066B input is connected to temperature sensor output, which can be -2.5mV.

    The customer want to know when control pin is low(connected to GND) and -2.5mV applied in input pin, what will happen in output pin? Will it be 0V or -5V?

    And  can CD74HC4316 and TMUX1511 support this application?

    Input: from -2.5mV to 22.5mV

    Control pin: High=5V, Low=0V

    Output: When control pin=High, output=input;  control pin=Low, output=GND; 

    Best regards,

    Dylan

  • 0 in reply to Dylan Zheng
    TI__Expert 5660 points

    Hi Dylan,

    For CD4066B, the control pin only determines if the signal path is on/off. Our switches are passive so that the input signal (positive or negative) is passed essentially unaffected, so signal input pin will equal signal output pin. So you are correct that when control input is high, the output = input. For this particular device, when the control input is low, the switch enters the high impedance state (so input pin will not be connected), and the output pin is tied to VSS (-5V).

    Actually, TMUX1511 will not be an option for this application as the signal will be negative and TMUX1511 does not support negative input signal within recommended operating conditions. 

    May I ask why you are interested in CD74HC4316? 

    Why do you need the output tied to GND when the control pin is low? Is it acceptable for your application to have a switch where the output is not internally connected (not GND) when in the high-impedance state?

    Regards,
    Kate