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Hi,

Last night while working with the Si5351a I noted something interesting, that made me recheck the spec sheet several times:

At least in my Si5351a the power level are inverted!

In the App Note (AN619) they say clearly and I quote:

=============%<==============================
CLK0_IDRV[1:0] CLK0 Output Rise and Fall time / Drive Strength Control.
00: 2 mA
01: 4 mA
10: 6 mA
11: 8 mA

=============%<==============================

In english: the least to significant bits of that register controls power, you write a number to it and get a different power level like this:

0 > 2 mA
1 > 4 mA
2 > 6 mA
3 > 8 mA

But I measured and checked the code it TWICE! (and more times also).

And the power level I get by using this is exactly REVERSED, that's:

3 > 2 mA
2 > 4 mA
1 > 6 mA
0 > 8 mA

That can be related to the reports on the birdie, and the fact that when you "increase the power" the birdie disappears...

If the App Note is wrong, like I have tested, then they are "decreasing the power" and then it make more sense that the birdie gone away.

I haven't checked other Si5351a for this defect (it's unlikely that all my Si5351 are from different lots, so all must behave the same) and also not checked other's libs code to see if they are doing it like the AN or if they found also this.

I repeat, this is an observation from my side that is interesting...

Can anyone out there measure your Si5351a for power levels correctness to clear if it's an error of my Si5351a or my setup? (please report what lib are you using)

73 de Pavel CO7WT.

PS: As some of my friends say:

The mind work like a parachute: "it works better when is opened"