CD – Bit Binary Counter. The CD is a ripple-carry binary counter. All counter stages are master-slave flip flops. Time-delay circuits. Data Sheet. CD datasheet, CD pdf, CD data sheet, datasheet, data sheet, pdf, Fairchild Semiconductor, Stage Ripple Carry Binary Counters. Stage. DATASHEET. Features. • High Voltage Types (20V Rating). • Medium Speed Operation. • Fully Static Operation. • Buffered Inputs and Outputs.
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CD4020 – 14-Bit Binary Counter
From your data you can see that Q1 the LSB is toggling on every negative edge pulse as you would expect. Q1 is the first bit in the counter. However the next available output is Q4 – this will be the fourth bit in the counter.
That means that you cannot see Q2 or Q3. You would expect to see Q4 toggling at one eighth of the rate of Q1 – you are. So everything is working correctly. The reason there are only 12 outputs is simply due to lack of pins – standard DIP packages back when the part was made were typically 8, 14, or 16 pins. Having the higher order bits is in many applications more useful than the low order bits, so the designer chose to break them out.
Having the least significant bit is also quite useful. You can for example you feed in a pulsed analogue input e.
This sort of signal is no good for feeding standard digital logic, but the CDB uses a Schmitt trigger input to clean it up. From Q1 you will get a nice digital clock signal out, albeit at half the frequency of the oscillator.
Why ripple counter increments on each 8th pulse Ask Question. Why is this division with the factor 8 happening? If you look at the datasheet you linked to and see the diagram in the top-right corner on the 1st page – do you notice how the outputs are labeled? Do you see that there is no Q2 or Q3 output?
We can see from the datasheet, that the CD has the following block diagram: Notice the naming of the outputs, you have Q1and Q4-Q Note also that it is a stage counter, which means the counter internally has 14 outputs.
Lets do a quick truth table to confirm: Alexander Having divide by 2 can also be useful. The answer will depend on looking back in time at old circuits from the early ’90’s to see what they were using the part for.
CD DATASHEET PDF DOWNLOAD
To be a little nit-picky, it’s not clocked and it’s negative edge sensitive. But, Alexander, the information is otherwise completely correct: Alexander in fact that is then one possible use for the Q1 – it will give you a nice clock signal from a narrow ddatasheet input.
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