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I'm looking at one of a stocked TCXO that suits the frequency and other system specifications like package etc, namely the 589R130X2C, except for the recommended Vcc of +3.0V for this part.

I'm tempted to say it probably should work with a +3.3V supply, after all what's 10% more on the Vcc than recommended ? However I do have a doubt, and I am not a TCXO manufacturer or designer ...

What could be the implications of supplying 10% more voltage to such a crystal specified for 3.0V (or any other similar TCXO device) ? Is this Vcc generally a hard absolute limit, is it an output voltage-swing limit, frequency tolerance killer, or other potential out-of-spec that may occur with time operating at an elevated Vcc ?

Any thoughts on this from personal experience ? Unfortunately the +3.3V is not available, and reducing system Vcc to +3.0V is not an option, even with an LDO ...

Bimpelrekkie
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citizen
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  • 1) your text is a "wall of text". If you split the text in a few paragraphs it becomes easier to read. 2) *I'm tempted to say it probably should work with a +3.3V supply, after all what's 10% more on the Vcc than recommended ?* What does the datasheet say? Look at the **maximum rating** to tell you what can be used. 3) asking for products is off topic, learn to search for a product meeting certain requirements by watching this video by Dave from the EEVBlog: https://www.youtube.com/watch?v=zqlAq266aTs – Bimpelrekkie Nov 24 '21 at 15:16
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    Also include a proper link to "589R130X2C" or whatever it is as a search on "589R130X2C" only gives garbage results. *Is this Vcc generally a hard absolute limit* The maximum rating is, exceed it and **you're on your own**, there is **no guarantee** that the device will work or not. The **recommended Vcc** is just that, recommended. Specifications are generally guaranteed when you use that value for Vcc. If you use a higher Vcc (but stay under the **absolute maximum Vcc**) then usually you get similar performance like the same frequency accuracy and drift. – Bimpelrekkie Nov 24 '21 at 15:18
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    We can only speculate on the actual performance effect because the topology is not specified. It could have no effect beyond a linear extrapolation of 0.40 ppm / 5% Vcc deviation specified under "frequency stability" in the datasheet. It could also unacceptably skew the operating point of the feedback amplifier that oscillates with the crystal and reduce loop gain, while increasing phase noise. You'd need to either contact the manufacturer or take the expense of characterizing the operation of these oscillators under your proposed conditions if you wanted to be sure. – nanofarad Nov 24 '21 at 15:52
  • There, more readable. Since the datasheet mentions a Vcc max of 6.0 V for all these devices, I am quite sure that you can use your 3.0 V devices at 3.3 V. The TCXO will not be damaged. As mentioned elsewhere: the specifications will no longer be guaranteed. Only if you **must have** the guaranteed values for the 3.0 V device at 3.0 V, then you should not use 3.3 V. But if you can tolerate frequency inaccuracy and drift, then it is OK to use 3.3 V, it all depends on your application. – Bimpelrekkie Nov 24 '21 at 17:33

2 Answers2

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The datasheet for this device specifies a 5% tolerance for Vcc. So, the 3V version is specified over a range of 2.85V to 3.15V. The maximum specified supply voltage is 6V.

This suggests to me that you will not damage the device by operating it at 3.3V, but it may not meet any of the manufacturer's other specifications. For example, the actual frequency stability might be much worse than the datasheet maximum.

Elliot Alderson
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To be 100% sure would require talking with the manufacturer. However, What I think you’ll find is that it works fine but the frequency is trimmed (or otherwise centered) for 3.0V so running at 3.3V will mean that nominal frequency is a little off so your tuning range is slightly shifted high (or low). By slightly, we’re talking < 1ppm kind of error.

Minor point - your output waveform high/low voltage values will be slightly higher as well.

65Roadster
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  • ±1ppm or even ±2ppm could be tolerated. I have been in contact with the manufacturers meanwhile, but for some unforeseen reasons it's been taking longer than usual to get a reply ... hopefully I'll have one soon. In the mean time thanks for the suggestions - they do make sense... – citizen Nov 24 '21 at 16:24
  • The data sheet specifies 0.4ppm for a 5% change in supply voltage. That’s why I roughly guessed <1ppm for your 10% shift from 3.0C to 3.3V. – 65Roadster Nov 25 '21 at 16:15