CC2340R2: Specifications for 32.768kHZ and 48MHz crystals

Luke

Expert 3730 points

Part Number: CC2340R2
Other Parts Discussed in Thread: SYSCONFIG

Tool/software:

Hi team,

Where can we find the following specifications for the 32.768kHz and 48Mhz crystals as required by CC2340R2?

I'm expecting to see ppm accuracy at ambient, due to aging and over temperature but am unable to find them anywhere.

Best,

Luke

9 months ago

+1 Bun Kuch 9 months ago

TI__Expert 6450 points

Hi Luke,

Here is our crystal selection guide for the CC23xx devices: https://www.ti.com/lit/an/swra495k/swra495k.pdf

But that spec is typically +/-40ppm

Best regards,

Bun

0 Luke 9 months ago in reply to Bun Kuch

TI__Expert 3730 points

Thanks for the quick response Bun!

The Crystal App Note also references SWRA640H, HW Config and PCB Design Considerations.

The SWRA640H is titled for CC13xx/CC26xx. Does it also apply to CC23xx or is there another similar app note for that?

Best,

Luke

0 Bun Kuch 9 months ago in reply to Luke

TI__Expert 6450 points

Hi Luke,

Only a few sections apply to the CC23xx, such as the layout section minus the balun, so we generally don't recommend it.

Best regards,

Bun

0 Luke 9 months ago in reply to Bun Kuch

TI__Expert 3730 points

Bun,

Makes sense, thanks for the help!

-Luke

0 Luke 9 months ago in reply to Luke

TI__Expert 3730 points

Bun,

Sorry to reopen this one again but does the crystal tuning section apply to CC23xx at all? If not, do we have anything similar to find this information?

The TRM references the HFXTDYN and HFXTTARG registers but does not define the Q1CAP or Q2CAP fields in any detail. (unless I missed it somewhere)

Best,

Luke

+1 Bun Kuch 9 months ago in reply to Luke

TI__Expert 6450 points

Hi Luke,

Crystal tuning for the cc2340 is a bit different. The steps are below:

1. Use SmartRF 8 and use continuous TX

2. Using a spectrum analyzer, place a marker on the desired frequency

3. Tune Q1 and Q2 such that the measured frequency is within +/- 2KHz of the desired frequency

4. Convert the value to hex and update sysconfig

0 Luke 9 months ago in reply to Bun Kuch

TI__Expert 3730 points

Thanks Bun! Is this information documented anywhere at this time for later reference?

-Luke

0 Bun Kuch 9 months ago in reply to Luke

TI__Expert 6450 points

It should be in the CC2340 equivalent of the SWRA640 but it is still a work in progress.

Bun

Bluetooth®︎

Bluetooth forum

CC2340R2: Specifications for 32.768kHZ and 48MHz crystals