PLL Calculations

I've used the ubiquitous 4046 PLL a few times, however I've never really found any proper calcs for it, I usually just approximate values from the data sheet.
Has any of you seen a online calc or even equations for the vco for the 4046 (not 7046, or 9046 which are different)?

Why not go with more modern devices. Many chip makers like analog devices have design tools/wizards for their parts and they are generally simple to use, for example Analog Devices has ADISimPLL which you can download for free, it builds your loop filter and everything.
Learn more:
https://form.analog.com/Form_Pages/RFComms/ADISimPll.aspx

That is my same frustration with the 4046. It is a very useful building block, but its specifications are very loose. And they become worse at lower voltages.

On the circuits I've built, I've always have had a way to trim R1 and r2's values, to obtain the desired center frequency.

Maybe I should modernise and use later devices.
There is a 9046 which is similar to the 4046, but it has a charge pump o/p on the phase comparator, online calcs are available for it, and its probably a better device.