Hi,
Straight forward way to find the ouput voltage value in the datasheet:
* open the PDF
* go to chapter "Electrical specifications" (it´s only one page with voltage specifications)
* do a serach for "output" (since you want the information of output voltage)
find:
* "TTL Outputs" specifications --> isn´t what you are looking for. skip
* "LED Outputs" specifications --> isn´t what you are looking for. skip
--> * then "100BASE-Tx Transmit --> this is what you want .. or
--> * then "10BASE-T Transmit --> this is what you want
This way it takes just 5 seconds to find the desired values.
***
It´s not guess, not just an opinion:
It clearly says: "measured differentially after 1:1 transformer"
It also says about the 100 Ohms termination.
And it says, that it´s different for 100BASE-T vs 10BASE-T
Copied from the datasheet:
View attachment 182948
Single ended: Sadly it seems I can´t be clear enough. I just can repeat.
* The chip is not designed for single ended output at all
* the single ended voltage levels are not specified .. and thus not guaranteed at all
* measured single ended values are meaningless. they may vary with time with temperature with production batch, with chip version. Nothing you can rely on.
****
2)
Here you talk about the bias voltage on the center tap to be 3.3V.
I could not find this information in the datasheet.
Nor did I find any information where you did get this information from.
And here is the point: these missing informations take long time for us to find. It makes it hard to help.
Usually I don´t do this, but now I took the effort and did a seach through various manufacturer documents.
I was successful at he "HW design checklist".
(Why didn´t you tell? It´s so easy for you .. compared to the effort on our side)
Indeed there is a circuit with CT connected to 3V3. Now your math makes sense.
And your worries make perfectly sense. Now I can fully agree with you that the datasheet information is odd.
Trouble is: I can´t tell what information is correct.
The only way I see is to contact the manufacturer on this.
My guessing - nothing you can rely on:
* the circuit in the HW design checklist is correct (complies with "MICREL Evaluation board schematic" provided in the "Supporting Collateral" .ZIP file)
* the datasheet information "all outputs" should be "all outputs except Tx pins"
Klaus