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Confusion / Clearance with CD4046 VCO

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darryl_co

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Hi,
I have a confusions with using CD4046
The Ic is rated 3 to 18v then why the datasheet says 5V,10V and 15V ratings.
Does that mean it should be operated on 5,10 or 15 Volts VDD?
Need Clearance that for a given values of R1 and C (Only VCO section used) say the frequency range is 1khz to 10khz for a VDD of 5V and VCO=1V to 0.9*VDD if I change VDD to 10V and VCO=1V to 0.9*VDD(10V) will the frequency rage increase or freq band get shifted ?
PS: VCO=1V to 0.9*VDD read in an application note,unfortunately unable to find it to upload
 
Hi,
I have a confusions with using CD4046
The Ic is rated 3 to 18v then why the datasheet says 5V,10V and 15V ratings.
Does that mean it should be operated on 5,10 or 15 Volts VDD?

No. It means that the maker choose to characterize the circuit's operation at those three voltages.

Data sheet is here.
 
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confusion still exist.Can I use it at say 9 or 12 volts ? and will the output swing from 0v to 9v or 12v(square wave) If yes my confusion is cleared.
 
confusion still exist.Can I use it at say 9 or 12 volts ? and will the output swing from 0v to 9v or 12v(square wave) If yes my confusion is cleared.

Yes, as with all CMOS circuits, the output voltage swing will be from ~0V to ~Vdd. You will have to trim the center frequency by changing R or C.
 
Please help with the vco frequency relation with supply voltage
Fig 4 from the above data sheet. "typical center frequency as a function ofC1 and R1 at VDD=5v, 10v and 15V"
The part will work at 7.5V. To get this graph you need to draw a line in between the 5V line and 10V line.
The part will work at 9v, use the 10V line and know it is off a little.
 
ronsimpson - The graph shows the relation of center frequency between selected capacitor and resistor value at VDD.I need to know relation of frequency band/range at a given VDD,say 10V, for a vco supply 1V to 0.9 VDD
 
ronsimpson - The graph shows the relation of center frequency between selected capacitor and resistor value at VDD.I need to know relation of frequency band/range at a given VDD,say 10V, for a vco supply 1V to 0.9 VDD


Hi. See figure 22 in the attached.
 

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VCO Bandwidth

What I understand by the figure/graph is that the Vcc has no effect on the bandwidth of the vco output frequency
 

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What I understand by the figure/graph is that the Vcc has no effect on the bandwidth of the vco output frequency

Hi. As a percentage, I agree with your understanding of the figure. It's roughly, BW = Fo ± (.15*Fo) for the linear portions of the curves. The absolute bandwidth increases as Vcc increases.

Edit: I just noticed the figure 22 I provided is for the HC and HCT series of the device. Your inquiry is about the original series device. If you look at Figure 8 in the first datasheet posted (the correct data sheet), you can see that Fmax/Fmin (bandwidth) is a function of the ratio R2/R1, where VCO control voltage ranges from from Vss to Vdd. Fmax/Fmin can be as great as 60.
 
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