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Studio Bluetooth Forum Discussions

Anonymous
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Hi,

We observed XO_IN A4 pin load to our reference clock input (supplied from oscillator or function generator).

1.8Vp-p signal becomes ~1.2Vp-p when connected to XO_IN pin of Cypress chip. See attached waveforms of reference clock without and with connections.

We would like to know from Cypress support team what could be reason for loading effect on input reference clock. We tried reference clock from oscillator and function generator, observations are same.

Thank you,

Pravinkumar

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1 Solution

I have verified with a HW engineer and the upper limit of 1.2V ptp still holds for the A2 part.

View solution in original post

10 Replies
Anonymous
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mifo

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I refer to the section on reference frequencies of the 20706 datasheet. I found that the acceptable range for ptp voltage for external reference frequency is between 400 and 1200 mV. This could be the issue you are refering to.

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Anonymous
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Can you please mention the page number in the 20706 datasheet from where you found that info ?

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Anonymous
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In our design case, we have IO voltage at 1.8V, thus, we expect to drive external reference clock at the same IO voltage i.e. 1.8V.

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Page 20, "6. Frequency References"

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Anonymous
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Can you please tell me what document you are referring to  ?

Our question was based on Section 1.8 ( Clock Frequencies) of 20706A2 datasheet.

Thank you,

Pravinkumar

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I'm attaching here as a picture:

20706.jpg

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Anonymous
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Hi,

I understand that the attached information is of CYW20706 UA1 part, I would like to know if it is valid for CYW20706 UA2 part also as we are using UA2 part in our design.

Our design has IO Voltage 1.8V pp and we are feeding external frequency with 1.8V pp, 'the Input Signal Amplitude' parameter in the above attachment says that the input voltage must be between 0.4 - 1.2 V pp. Please suggest if we can feed with external frequency that is 1.8V pp.

Thank you,

Pravinkumar

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CYW20706 Datasheet​ - A2 datasheet

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I have verified with a HW engineer and the upper limit of 1.2V ptp still holds for the A2 part.