Electronics > Beginners

How to determine if PLL 4046 is locked?

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ZeroResistance:

--- Quote from: Benta on August 11, 2018, 08:53:10 pm ---
--- Quote from: imo on August 11, 2018, 08:40:49 pm ---
--- Quote from: Benta on August 11, 2018, 08:22:16 pm ---And No, the XOR does not "continually wobble", no idea where that came from.

--- End quote ---

--- End quote ---

Your picture does not represent "wobble" in any way, the triangular waveform is synchronous to the PD and VCO and will not result in frequency or phase "wobble".

That aside, the scha002 and scha003 are the dodgiest application notes from TI ever, and were probably written by an intern during the summer vacation. I've ranted about those in other threads.

--- End quote ---
I was under the impression that when both VCO and Signal In are in phase the phase comparator should have output 0 volt's.

ZeroResistance:

--- Quote from: imo on August 11, 2018, 08:16:27 pm ---While trying to understand your schematics (I have to rotate my notebook upside down) - what the 10k pot-trimer actually does?
I think it cannot be wired that way..
Could you describe what the system shall actually do?

--- End quote ---

I was following http://uzzors2k.4hv.org/index.php?page=pllsstc1

iMo:

--- Quote from: ZeroResistance on August 12, 2018, 05:44:11 am ---I was following http://uzzors2k.4hv.org/index.php?page=pllsstc1

--- End quote ---
Then you miss the 120k resistor at the 10k pot's wiper (from the pot's wiper to the LP filter)..

ZeroResistance:

--- Quote from: imo on August 12, 2018, 06:30:53 am ---
--- Quote from: ZeroResistance on August 12, 2018, 05:44:11 am ---I was following http://uzzors2k.4hv.org/index.php?page=pllsstc1

--- End quote ---
Then you miss the 120k resistor at the 10k pot's wiper (from the pot's wiper to the LP filter)..

--- End quote ---

I have it soldered on my board, I missed it while drawing the schematic.

Benta:

--- Quote from: ZeroResistance on August 12, 2018, 05:41:28 am ---
I was under the impression that when both VCO and Signal In are in phase the phase comparator should have output 0 volt's.

--- End quote ---

No. From your link:
"The phase locking itself works by using an XOR gate to detect the phase angle between the two inputs, pin 3 and 14. The output from the XOR (pin 2) is a PWM signal, and the duty cycle will vary from 0 to 100% as the phase difference between two 50% duty square waves moves from 0 to 180 degrees."

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