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CD4052B: OFF/Inhibit input resistance and/or inhibit schematic of switch?

Valorie P
Prodigy 10 points
Part Number: CD4052B
Other Parts Discussed in Thread: CD4502B, MUX507

Hello,

I am considering the CD4052B (multiple in parallel) to use in switching 60 transducers between different connections. This purpose would require the disabled chips to be very high impedance.

My issue right now is the data sheet says that the chip has a very high OFF state resistance. With the chip we currently have and are testing right now, when the chip is inhibited, it is still drawing a considerably large current (more than the pA range suggested in the data sheet).

I would like to know what the chip/circuit looks like inside when it is disabled, and where the input goes in this mode? And if I could get the specific value of the input resistance in the OFF mode. I am currently using 1.5MHz signals with the device.

Thanks

  • 0
    TI__Intellectual 2900 points
    Hi Valorie,

    In your application, you are pursuing not only low channel off leakage, but you want super small pin capacitance as well.

    Your test signal is 1.5MHz and CD4052B 's pin capacitance is 5pF at the input side. Take 20Vams signal for example. The "leakage" through capacitance is 20V*(2*3.14*1.5MHz)*5pF = 942 uA. Therefore, your AC signal and the chip's parasitic capacitance dominate the leakage current.

    Since you have 60 transducers, I would recommend MUX507. It is differential 8:1 multiplexer and CD4502B is just differential 4:1.