nickeh
Posts: 12
Joined: Thu Feb 20, 2014 9:30 am

4066 CMOS switch

Mon Feb 24, 2014 5:28 am

Hi,

I want to use a GPIO (output) to switch a 4066 (control input). Can I connect a GPIO output directly to the control pin or do I need a resistor in between? And how should it be connected (resistor between GPIO and control pin or how)?

Thanks in advance!

Paul Moir
Posts: 46
Joined: Wed Dec 04, 2013 7:25 pm
Location: Nova Scotia, Canada

Re: 4066 CMOS switch

Mon Feb 24, 2014 7:34 am

You can directly connect. No need for a resistor.

That said, what are you supplying your 4066 at? At 5v you need 3.5v minimum on a control line to switch it on, so you would have to level shift in that case. Check the datasheet and you'll see what I mean.

EDIT: You know, the 74HCT4066 (but not the 74HC4066) is guaranteed to switch on with a 2v control with 5v Vcc. I guess it depends on exactly what you're trying to do though.

nickeh
Posts: 12
Joined: Thu Feb 20, 2014 9:30 am

Re: 4066 CMOS switch

Mon Feb 24, 2014 8:51 am

Thanks Paul,

I have the HCF4066BE and I was thinking of running it on 3.3V since it can work from 3-20V. Lets see if it works :)

Best regards
Nicke

Paul Moir
Posts: 46
Joined: Wed Dec 04, 2013 7:25 pm
Location: Nova Scotia, Canada

Re: 4066 CMOS switch

Mon Feb 24, 2014 6:22 pm

Ok, no problem then with a 3.3v power supply. At least I think it should work perfectly normally down that low. The "On" state resistance gets higher as Vdd drops, so I guess you can expect a few K across each switch.

nickeh
Posts: 12
Joined: Thu Feb 20, 2014 9:30 am

Re: 4066 CMOS switch

Mon Feb 24, 2014 7:39 pm

Yes, it worked perfectly with one 4066. I am hoping to power two 4066 from the RPi 3.3V, according to the specs the power need is really low so it should not be a problem. Across the switches I measured 190 ohms which was less than I expected.

Thanks for your support Paul

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