Hi,
I'm developing a custom board based on your schematic for the DA14580 (E-DA14580A3DB-P_va_schematic_0.pdf) and I have a few questions about some of the components you used.
1) I could not find the specific 16 MHz crystal that you used available on the market (NX2520SA). Is there a comparable one you recommend that can be used in place of this?
2) I also could not find the 1uF low-ESL capacitors that you used. Are there other low-ESL capacitors available that you recommend in 0402 packaging? And do they need to be low-ESL capacitors?
3) Do you have any information about the antenna you used in the design? If not, do you know if there is a chip antenna available on the market that has comparable characteristics to the one you used?
Thanks!
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Hi mjr3vk,
1) Any XTAL16 within the 580 requirements would do (16MHz Crystal Oscillator Recommended Operating Conditions), other possible XTAL's would TSX-3225, FCX06 LF, ECX-1637, FA-128.
2) Regarding the 1uF caps, for the caps connected to the VDCDC and VDCDC_RF its recommended to use low ESL caps, for the VBAT3V and VBAT_RF we have customers that use higher ESL capacitors and dont have any issues.
3)关于天线,您将be able to find an antenna guide in the Application Notes section in the Documents tab, the document is called AN-B-027:Designing Printed Antennas for Bluetooth Smart and there is also a zip file with the antenna DXF files, additionally you can check the AN-B-018:DA14580 Checklist for schematic and PCB layout, it has also additional info for the XTAL16 selection.
Thanks MT_dialog
Thank you for the response!
I am considering using a chip antenna from Johanson Technology (part number 2450AT18A100, see attached datasheet) in place of the IFA antenna that you specified in the AN-B-027 document. It has a similar return loss and a 50 ohm impedance. Do you foresee any issues with using this antenna?
Hi mjr3vk,
The ceramic antenna that you mention is the same antenna that is used in the IoT reference design, so should be ok with that.
Thanks MT_dialog