PLL Frequency Multiplier

Thread Starter


Joined Feb 23, 2007

I am using the LM565 PLL and a 74LS90 decade counter to design a times 5 frequency multiplier. I have figured out how to use the counter but I am having trouble with the LM565 PLL.

My multiplier should work from (input range) 500Hz to 2kHz (ie. my outout range is therefore from 2.5kHz to 10kHz). I need help selecting the free running frequency (fo), hold in range (fH), and capture range (fc), and 3dB frequency of the lowpass filter (flpf). From the LM565 data sheet they give the following equations,

fo = 0.3/(R1*C1) fH = +OR- 8*fo/(Vc) fc = +OR- sqrt(fH * flpf)

Vc is the total supply voltage. If anyone can give me some hints and advice I would greatly appreciate it.


Any hints would be appreciated.