Faced with such a problem. There SI5351 chip labeled A3BS 405. When programming these chips are no problems!
There are lot of chips labeled SI5351 AFTP 137.
There were problems with the programming. HN output of these chips, the frequency is unstable and has a deviation of about ± 1 MHz. Chips marked AFTP 137, only work with Arduino library (Etherkit_Si5351).
Chips SI5351 marked A3BS 405 work for all libraries!
These devices (AFTP 137) differ in the structure?
SI5351 chip labeled AFTP 137 has a special series?
Or the party SI5351 marked AFTP 137 fake?
Help to solve the problem.
It may be that these two circuits, various other control commands?
That is, for 405 A3BS need one code and the other for 137 AFTP?
No. We have only one version of these ICs. Please initiate a return for the parts that malfunction. It is likely a quality issue (i.e. a "faulty" device that we need to investigate for the cause of failure).
Last questions. It could get to the sale of a defective batch of chips?
Whether the party is made with this label? 137 AFTP.
Maybe it's a fake from China?
As far we know, these are not fake. However, if you purchased it from a distributor and initiate a return through that distributor for a "Quality issue", we will inspect it and tell our findings (including if this part turned out to be a fake IC).
The 137 AFTP top marking indicates that the IC is legitimate.