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Topic: Si5351A clock generator specification mistery! (Read 247 times) previous topic - next topic

pietrafesa

Aug 12, 2020, 03:06 pm Last Edit: Aug 12, 2020, 03:10 pm by pietrafesa
Hallo guys!
In the Silicon Labs Si5351A clock generator specification sheet I see two values ranges for the same parameter CORE SUPPLY VOLTAGE (VDD).

In the "short" features page I see:
Core VDD: 2.5 or 3.3 V

Than, when I go deeply at page (5 of 41) I see two ranges for "CORE SUPPLY VOLTAGE" Vdd, as you can see in the attached picture:
MIN     TYP      MAX
3.0      3.3         3.6
2.25    2.50      2.75

Is there anyone may explain me why they declare two ranges instead of one?
Thank you very much indeed.

Roberto.


aarg

  ... with a transistor and a large sum of money to spend ...
Please don't PM me with technical questions. Post them in the forum.

pietrafesa

Dear friend aarg, first and foremost thank you for quick reply.
I have not so much competences to understand 100% the matter of your reply, please accept my apologies.
You said "with transistor". I understand that one row is intended if I don't use a transistor, and one other row is intended (like you suggest) with transistor. What row is intended without transistor? The first above or the second below?
Thank you so much.
Roberto

aarg

That is in my signature file. I was just displaying the image you attached so people could read it.

I read the entire data sheet, I think the chart you are  trying to read is missing information. You will have to contact SI about it.
  ... with a transistor and a large sum of money to spend ...
Please don't PM me with technical questions. Post them in the forum.

pietrafesa

Thank you so much for the suggestion.
I will search for an updated datasheet or I will contact the manufacturer.
Have a nice day.
Roberto.

WattsThat

From the cover page of the datasheet:

Core VDD: 2.5 or 3.3 V

What's the confusion?
Vacuum tube guy in a solid state world

TomGeorge

Hi,
What the spec is telling you it will work with 2.5V OR 3.3V core voltage supply.

The reason is there are 2.5V and 3.3V systems that use the Si5351A.

Tom... :)
Everything runs on smoke, let the smoke out, it stops running....

aarg

#7
Aug 14, 2020, 01:20 am Last Edit: Aug 14, 2020, 01:23 am by aarg
Hi,
What the spec is telling you it will work with 2.5V OR 3.3V core voltage supply.

The reason is there are 2.5V and 3.3V systems that use the Si5351A.

Tom... :)
Then how do you explain the unique maximum and minimum for each voltage? :) If it will do both voltages, one maximum and one minimum would be the norm. Some minimum less than 2.5V and some maximum greater than 3.3V.

How could the same part have a maximum of 2.75V and a minimum of 3.0V?
  ... with a transistor and a large sum of money to spend ...
Please don't PM me with technical questions. Post them in the forum.

TomGeorge

Hi,
The datasheet is not clear on that.
I would assume if you put between 2.25 and 2.75 on Vdd, the core is internally run off a 2.5V bus.

I would assume if you put between 3.00 and 3.60 on Vdd, the core is internally run off a 3.3V bus.

This goes in line with the Vddo voltages, it is selectable by the user.

There doesn't seem to be a part number to designate any particular core voltage.

Have you googled    si5351a arduino

It returns many examples of how the IC is used with arduino and module PCBs.

Tom... :)
Everything runs on smoke, let the smoke out, it stops running....

MarkT

Probably just means these are the voltages the die is tested at in manufacture, they don't guarantee
its upto spec outside the measured ranges.  Is a little bit odd though, I would have thought they
just need to give the whole range, simpler and less confusing and I don't see how it could fail to
operate at different voltages.
[ I DO NOT respond to personal messages, I WILL delete them unread, use the forum please ]

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