Part review – NXP 74HC4066 Quad bilateral switch IC

Hello readers!

Today we are going to examine the 74HC4066 quad bilateral switch IC. My reason for writing this comes from a comment left by a reader on chapter nine of the Arduino tutorial. They suggested using a 4066 IC to control the cathodes of the LED matrix instead of resistors and NPN transistors. This was a good suggestion, however the 4066 can only switch a current of 10mA per pin. Luckily the 74HC4066 can handle up to 25mA per switch – so we’ll look into this instead.

First of all, let’s say hello:

74hc4066

This is the 14-pin DIP package. It is also available in surface mount, and other newer package styles. Although we are looking at an example from NXP, according to my main component supplier (element-14/Newark) this IC is also manufactured by Texas Instruments, ON Semi, ST Microelectronics and Fairchild. So, what is a quad-bilateral switch? Four switches in one IC. Here is a diagram:

Imagine a simple normally-open push button. You press the button, and current can flow through the switch. Using the 74HC4066, when current is applied to the E pin, current can pass through from the matching Y pin to the Z pin. As you can see above, there are four of these switches in the IC. This is where the benefit of the IC comes to mind, normally one might use a 1k ohm resistor and an NPN switching transistor as an electronic switch, and I have done so myself. But when you need a few of them, it can be easier to start using these 74HC4066s as long as the current requirements are met.

With regards to the current the IC can switch, Is, the maximum is 25mA per switch. This is more than enough to run a typical LED, TTL logic gate, etc. The other interesting parameter is the turn-on and turn off times – at 6 volts it can turn on in around 10 nanoseconds and turn off at around 13 nanoseconds (so a rough calculation – say it takes 30 nanoseconds to switch on and then switch off, that’s 33.3 million times per seconds (33.3 MHz). All these parameters and more are available from the data sheet (pdf). Someone correct me if I’m wrong!

That’s enough theory – let’s put it to work now. Our first demonstration is quite simple – just switch on and off some LEDs via a 74HC595 shift register and an Arduino. We send a number (0, 1, 2, 4, 8 ) to the shift register, which stays off, then sets pins Q0, Q1, Q2, Q3 high in order, which in turn activate the switches 1~4 on the 74HC4066. The 74HC4066 sends a current to each LED connected to the switch outputs.

Here is the schematic:

demo1schematicsmall1

Laid out on the breadboard:

demo1small

And the ubiquitous video:

And here is the Arduino sketch: demo1.pdf. Well that was interesting. I know these simple demonstrations may be… well a little simple, but after taking the time to build them from scratch you get a better understanding of the part and how they work. Practice makes perfect and all that. Anyhow, let’s have a look at something much more interesting – a very basic (!) digital to analogue converter. Consider the circuit below:

demo2schematic

The 74HC4066 switches creates a final voltage through the sum of various currents being switched into the final output. First of all, here is a video of the switches being turned on and off one at a time:

and the corresponding Arduino sketch:demo2.pdf. The next video shows the results of sending decimal numbers 0~15 to the shift register – in effect continually adding the outputs of the pins until all pins are on, then in reverse:

and the corresponding Ardiono sketch:demo3.pdf.

Well I hope you found this part review interesting, and helped you think of something new to make. In conclusion I would consider the 74HC4066 easier and quicker for end user to use in projects (less pins to solder, etc) however using it could cost more depending on the volume required. Furthermore, this would only apply if the current restrictions of the IC are met.

So have fun and keep checking into tronixstuff.com. Why not follow things on twitterGoogle+, subscribe  for email updates or RSS using the links on the right-hand column, or join our Google Group – dedicated to the projects and related items on this website. Sign up – it’s free, helpful to each other –  and we can all learn something.

Notes: In writing this post, I used information from NXP, plus information and circuit inspiration from various books by Forrest Mims III.

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John Boxall

Person. Founder and original author for tronixstuff.com. VK3FJBX

24 thoughts on “Part review – NXP 74HC4066 Quad bilateral switch IC

    1. John Boxall

      Hello Daniel
      I probably should have explained that earlier in the post. It was referring to the use of a 1k resistor and an NPN transistor used as a switch – provided the current limits are met. For example controlling the cathodes of an LED matrix. It is easier in that there are much less components to have to handle, and if you are soldering the project using this chip, 1 or 2 ICs are easier to solder in than many transistors and resistors.
      Thank you for your question.
      Cheers
      John

      Reply
  1. Robert

    Hi there Daniel

    I found a chip like this one… it’s number was 4016 which is discontinued… so the 4066 must be it’s replacement… in a Broadcast Electronics operations manual for their mixer model 4S50. they were using it as an analog switch, to switch on and off audio signals into the program buss. How much attenuation does this chip have? how much would leak thru when in the off condition? Data sheet says -50db but against a machinal switch when open is infinity.

    Thanks in advance
    Robert

    Reply
  2. Basava

    Hi,

    Please help me to design following circuit,

    Actually it is basic requirement, but I am facing difficulty to design,
    My Query is as follows,

    How to control IC 4066 (for switching action), I mean what is current and voltage supply for control lines, to make it ON or OFF, please help me with circuit diagram,

    Actually I want to control 4 lines (lines are less the DC 5V) and I want to Use IC 4066 instead of push button,

    Regards,
    Basava!!!

    Reply
  3. rednaskellar

    Hi John!
    Thank you for all your tutorials – they very usefull for me as a beginner in electronics.
    While reading this one I hit upon the idea to make an Arduino audio input/output switch. But I’m not sure if it’s possible with 74HC4066. Can I instead of LEDs in the first example switch several audio source, for example PC, CD player, etc.? And can I use than second one IC to switch the output audio signal between speakers or headphones? Of course I would switch separately left and right stereo channels.
    Do you think it’s possible?

    Reply
  4. Deepthi

    Hi John ,

    This is deepthi working in larsen toubro( Meter manufacturere’s ),just a simple query if you could clear me , earlier we were using 4016 in our Energy meters , but now NXP has suggested ous to use 4066 , concerned on this let me what are the Merits and De-Merits between the two
    Appreciate your ealiest reply .

    Reply
  5. Jeffrey

    Hi John, what would your suggestion be to decouple this IC? The standard 1 decoupling capacitor per IC or 1 decoupling capacitor per switch of the 4066?

    Reply
  6. Marco

    Hi John,
    This IC could be used with arduino for switching the button of a Garage door opener remote!?, If not, any recomendation?.
    Thanks

    Reply

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