CC1310 Load Capacitors

Dennis_

Other Parts Discussed in Thread: CC1310

When looking for crystals that meet the specifications of the cc1310 I found the Epson TSX-3224 24.0000MF20G-AC3 which has a load capacitance of 9pF. My first question is whether I should I set the config value such that CL_int = 9pF? ( my only concern is where to take into account the parasitic capacitance)

Also, I am confused why the crystal on the cc1310 launchpad (TSX-3225 24.000MF15X-AC3) has a load capacitance of 15 pF? It says in the "Configuring the CC1310 for different crystals" app note that " For reliable operation, TI recommends operating the crystal with CL from 5 to 9 pF".

Being equivalent in all cases except the CL, which crystal should i pick?

over 9 years ago

0 SVS over 9 years ago

TI__Genius 9705 points

Hello Dennis,

The default crystal load is set to 9pF, you need not tune Cl if you choose a crystal with this load requirement. It is also important to place the crystal very close to the the crystal pins to minimize parasitic capacitance. Cl for TSX-3225 24.0000MF15X-AC3 part used on CC1310 launchpad is also 9pF. Please refer to the following document for recommended crystals.

processors.wiki.ti.com/.../CC26xx_Crystals

Regards,

0 TA12012 over 9 years ago

TI__Mastermind 36395 points

If you got your information from Mouser, I think the issue is that they have the CL listed incorrectly.

www.mouser.com/.../

Correct listing at Digikey.

www.digikey.com/.../1825447

Always try to reach out to the manufacture and get the datasheet directly.

Regards,
/TA

0 Dennis_ over 9 years ago in reply to SVS

Prodigy 110 points

Hey thank you SVS and TA! I was indeed confused due to the wrong information on the Mouser website.

Just a quick follow up question. I would like to use the ABS06-32.768KHz-1-T 32kHz crystal. It has a load capacitance of 12.5 pF.

Am I right to calculate the capacitor values as 2*Load Capacitance- 2*Parasitic Capacitane == 2*12.5-2*2 == 21 pF (assuming around 2 pF parasitic)?

Thanks!!

Dennis

0 SVS over 9 years ago in reply to Dennis_

TI__Genius 9705 points

Hello Dennis,

The computation of load capacitor value for crystal is OK.

Regards,

0 Dennis_ over 9 years ago in reply to SVS

Prodigy 110 points

Thank you SVS.

Best regards,

Dennis

Sub-1 GHz

Sub-1 GHz forum

CC1310 Load Capacitors