Re: max. current through a 4066 switch

Joerg wrote: 
Hello Adam,


I cannot find the maximum switch current in any data *** of the 4000 or HC4000 CMOS analogue switches. I'm afraid I'll take the n or p MOSFET out of its ohmic region. I need to switch 10mA , and can afford up to about 1V drop. Can it be done with a 4066 (typ. Ron=80 ohm @ Vdd-Vee=12V) ?

If not how about the 74HC4066 (typ Ron=30 ohm @ Vdd-Vee=12V) ?
I want to avoid a relays if possible.


If you don't want to parallel some, how about using a FET such as the BSS123? About $0.05 in qties but you'd need to keep the gate a few volts above the highest expected signal level.



Joerg, the BSS123 might be a good option. I scribbled down the following;


          +6V
           o
           |          .---->
          100k        |D
           |      ||--'
           o------||<-.  BSS123
logic      |      ||--|S
input   /-----\       |
  ----> |4053 |       |
        \-----/       |
          |       ||--|S
          o-------||<-'  BSS123
          |       ||--.
         100k         |D
          |           '---->
          o
         -6V

My max signal amplitude to the BSS123s' will be +-2.5V. This corresponds to Vgs fluctuation of 6+-2.5V or 3.5 to 8.5V.
Charge injection and switch rate is not an issue since this is part of a gain setting circuit for DC measurements.
.

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