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.

CD4052B: Con, Coff vs. Vs/Vd Voltage

Part Number: CD4052B
Other Parts Discussed in Thread: TMUX6202, SN74LV4052A, TMUX1309

Hi

Do Con and Coff change with Vs/Vd input/output voltages?
In the customer's system, the CD4052B is connected in front of the ADC.
Only when the MUX input voltage is around Vdd/2=1.65V, the noise synchronized with the ADC sampling period is measured at X-COM.
I assumed kickback from S/H, but this situation only occurs around X-COM = Vdd/2.

1) What are the possible reasons?
2) Does TI have data like TMUX6202? (This is a customer request.)

* Current customer system and situation
Since there is only a small capacitance connected between X-COM and ADC IN, they will connect a resistor and test again.

Best regards,
Hiroshi

  • Please note the CD4000 devices have lousy electrical characteristics at low voltages, an no guaranteed characteristics at 3.3 V. Near VDD/2, the on-resistance is highest; I suspect that it is just too high for your ADC.

    Better use a low-voltage device like the TMUX1309 or SN74LV4052A (and these are cheaper than the CD4052B).

  • Hi Hiroshi-san,

    As Clemens indicated a possible reason for the noise is due to the high on resistance of the device when used in your application. Is using a lower Ron part like the TMUX1309 applicable here?

    Unfortunately, we don't have plots like the TMUX62xx since the CD4052B is a very old device. 

    Thanks!

    Alex

  • Hi Clemens-san, Alex-san,

    Thank you for your answer.
    We will propose TMUX1309 based on your advice.