Data sheet acquired from Harris Semiconductor. SCHSD. CAUTION: The CDB, CDB, and CDB analog multiplexers are digitally-controlled . Product data sheet. Rev. 12 — 25 March 4 of Nexperia. HEFB. 8- channel analog multiplexer/demultiplexer. Fig 5. Logic diagram. An IMPORTANT NOTICE at the end of this data sheet addresses availability, warranty, changes, use in . Product Folder Links: CDB CDB CDB.

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So – tell more about what is connected on the analog mux pins? But this happens even with 1k resistor on Input 4. Sign up using Facebook. But perhaps I can calibrate it.

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You show that you’ve got your “Signal” leads connected to the select inputs. From the Arduino wiki page, it reads “Futhermore, the is able to work with analog values; in the case of the Arduino, you are able to use the catasheet inputs with a voltage between V and route them to an Analog-In Pin on your Arduino. The Arduino has about 10Mohm resistance on the input side, so it shouldn’t make a difference, but the max reading was about instead of Is there a better alternative?

Still, I was hoping for a method that wouldn’t tamper with the input signal in any way: I’ve programmed a small routine that checks for consistency of the signal reading. I’m using digitalWrite on three pins to select the input port, and then waiting delay for 30ms before doing an analogRead on A0. I did try to fd4051b a 10k resistor in series with the input, but it changed the output. I’m trying to multiplex an analog input port on an Arduino Uno.

I’m using a breadboard of questionable quality. Problematic breadboards cause loose connections within the board which you cannot see and hence lead to situations such as open connections etc.


At the very least, connect a pullup resistor of about 10K between IN and the 5V power source.

Multiplexer CDB gives strange readings – Electrical Engineering Stack Exchange

Datasheet simulate this circuit — Schematic created using CircuitLab I’ve connected the input to 5V for testing stability of the reading. I’ve also tried adding a 1uF capacitor. Email Required, but never shown. If I start reading random ports between 0 and 7it reads correctly for about 10 seconds, then suddenly starts reading zero. But it changes nothing. If I read only port 4 for 30 seconds, it starts to read correctly and stable.

A 10K resistor works well in most cases. The is an analog multiplexer – it can switch analog signals between Vee I’m a bit lost to what the problem could be. Is it possible that they are getting triggered? Sign up using Email and Password. Look at page 4 of this guide. However, the control inputs require CMOS digital levels. I’ve connected the input to 5V for testing stability of the reading.

By using our site, you acknowledge that you have read and understand our Cookie PolicyPrivacy Policyand our Terms of Service. Post as a guest Name. I’d try using a different board.

But the documentation on their website is generally incredibly poor, so I wouldn’t be surprised. LawrenceNK1G, I’m going to read a lot of things, like pots, voltage dividers etc.

What is the signal source that you’re reading? The value then starts reading randomly. I saw a comment on the ‘arduino’ board which said that “the for loop repeatedly cycles count from 0 to 7, so [selector pins] will average 2.

Home Questions Tags Users Unanswered. I’ve experimented with various delay times, and 30ms seemed to improve things a lot when reading sequantially 0, 1, 2, Ideally something that would allow multiplexing without distorting the signal.


I’ve tried changing the pull-down resistor. The CDB Output is grounded via a k resistor, so that unconnected ports read 0.

Your drawing does not correspond with the nomenclature of the chip. I imagine it could be something with capacitance on the ports, but I have the impression that the multiplexer is actually supposed to support datasheet fast switching? By clicking “Post Your Answer”, you acknowledge that you have read our updated terms of serviceprivacy policy and cookie policyand that your continued use of the website is subject to these policies.

Wouldn’t the digital pins be able to sink fast enough that the IC would mux correctly? I haven’t seen the block diagram for the chip but it seems that you may be shorting something internally inside the chip which is why the input drops to 0V after a short time.

Though this may not be very relevant in this case, its important to note that the B is dayasheet CMOS device and hence anything less than 1. That is what seems to be the source of your problems. This means that this chip will not work with 3. Also the pulldown resistor need not be that high.

Post Your Answer Discard By clicking “Post Your Answer”, you acknowledge that you have read our updated terms of serviceprivacy policy and cookie policyand that your continued use of the website is subject to these policies. It still goes to zero.

Sign up or log in Sign up using Google. The IC has internal protection circuits.

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