CC1310: 32.768kHz crystals and its loading cap

Andy Lee

Part Number: CC1310

Hi,

I'm looking for correct P/N of the 32.768Khz crystal for CC1310 design and was confused by different descriptions on TI spec. and design files, would anyone clarify that:

1) load capacitance should always between 6pF ~12pF.

2) FC-12M: 12.5pF in the AN and C51:15pF load capacitance on LaunchPad are incorrect?

TI's Spec

Application Report: Crystal Oscillator and Crystal Selection for the CC26xx and CC13xx Family of Wireless MCUs

TI's Launchxl-CC1310_schematic.pdf

thanks!

over 3 years ago

0 TER over 3 years ago

TI__Guru**** 317180 points

From https://www.ti.com/lit/pdf/swra640:

With 12 pF + 15 pF the first term is 6.7 pF. With the parasitics you are inside 6 pF and 12 pF.

What was the question?

0 Andy Lee over 3 years ago in reply to TER

Prodigy 30 points

Oh, I just mixed up mind on the schemtic. thanks!

BTW, is it ok to use FC-12M crystal while its CL is 12.5pF?

+1 TER over 3 years ago in reply to Andy Lee

TI__Guru**** 317180 points

The xtal should have a Cload within what is stated in the datasheet (less than 12 pF)

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CC1310: 32.768kHz crystals and its loading cap