In the BOM for EVAL-ADAU1701MINIZ, (see atatched PDF, page 11 of 12) according to the description of crystal Y1 in this page, load capacitance is 18pF. However, the provided part number Abracon ABM3B-12.288MHZ-10-1-U-T has a load capacitance spec of 10pF.
What is physically on the Eval Board? 10pF or 18pF?
I found the discrepancy. An earlier revision of the board used the Citizen HCM49-12.288MABJ-UT, which is 18 pF. The latest board design uses the Abracon ABM3B-12.288MHZ-10-1-U-T, which is 10 pF. The BOM must have been updated with the proper part number, but the description still says 18 pF. Thanks for catching that typo.
The crystal oscillator on the ADAU1701 will have no problem driving either of these loads. The larger engineering board for the ADAU1701/ADAU1401A uses the 18 pF crystal, whereas the mini board uses the 10 pF crystal. We haven't seen issues with either design.
I am having a problem with my crystal in my ADAU1702 design. At power up the crystal does not start oscillating until I touch it with my finger.
The crystal I use is 7A-12.288MAAJ-T from TXC. According to the datasheet the load capacitance is 18pF and the shunt capacitance is max 5pF.The capacitors I use is 22pF (NP0)
What could be the reason for my oscillator not to start up properly?
Thanks and best regards
Please read this thread:
I hope that it helps you solve your problem. Please let us know if you have any other questions.