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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I’ve programmed a small routine that checks for consistency of the signal reading. If I read only port 4 for 30 seconds, it starts to read correctly and stable.
If I start reading random ports between 0 and 7it reads correctly for about 10 seconds, then suddenly starts reading zero. I’ve tried changing the pull-down resistor.
It still goes to zero. I’ve tried removing the pull-down resistor. The value then starts reading randomly. I’ve also tried adding a 1uF capacitor.
But it changes nothing. 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’ve experimented with various delay times, and 30ms seemed to improve things a lot when reading sequantially 0, 1, 2, I’m a bit lost to what the problem could be.
I imagine it could be something with capacitance on the ports, but I have the impression that the multiplexer is actually supposed to support very fast switching? 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. Daatasheet the digital pins be able to sink fast enough that the IC would mux correctly?
The IC has internal protection circuits.
(PDF) CDB Datasheet PDF Download – CMOS Analog Multiplexers / Demultiplexers
Is it possible that they are getting triggered? But this happens even with 1k resistor on Datasjeet 4. That is what seems to be the source of your problems. Problematic breadboards cause loose connections within the board which you cannot see and hence lead to situations such as open connections etc. I’d try using a different board. Also the pulldown resistor need not be that high.
A 10K resistor works well in most cases.
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. At the very least, connect a pullup resistor of about 10K between IN and the 5V dd4051b source.
I’m trying to multiplex an analog input port on an Arduino Uno. Datasheet simulate this circuit — Schematic created using CircuitLab I’ve connected the input to 5V for testing stability of the reading.
I’m using a breadboard of questionable quality.
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. You show that you’ve got your “Signal” leads dataheet to the select inputs. So – tell more about what is connected on the analog mux pins?
What is the signal source that you’re reading? LawrenceNK1G, I’m going to read a lot of things, like pots, voltage dividers etc.
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 analog inputs with a voltage between V and route them to an Analog-In Pin on your Arduino. But the documentation on their website is generally incredibly poor, so I wouldn’t be surprised.
Is there a better alternative? Ideally something that would allow multiplexing without distorting the signal. I did try to add a 10k resistor in series with the input, but it changed the output. 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 But perhaps I can calibrate it.
Still, I was hoping for a method that wouldn’t tamper with the input signal in any datashet The is an analog multiplexer – it can switch analog signals between Vee However, the control inputs require CMOS digital levels. Look at page 4 of this guide. Sign up or log in Sign up using Google. Sign up using Facebook. Sign up using Email and Password.
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