CC2570 32K Hz crystal optional?

cody lohse

Other Parts Discussed in Thread: CC2570

Hi,

I am looking at the CC2570 vs the Nordic AP2. The Nordic chip can synthesize the 32K Hz clock from the external 16 MHz clock, is this possible with the CC2570 or is the 32k Hz crystal required. If it is possible to use the CC2570 without the 32k Hz crystal do the input pins for the clock (XOSC32K_Q1, Q2) need to be tied to Vcc or Gnd?

Also, I see that the reference circuit documentation (SWRC225.zip) uses a 32 MHz crystal, can a 16 MHz crystal be used instead?

I appreciate any assistance,

Cody

over 12 years ago

0 Chatto over 12 years ago

TI__Genius 12545 points

Cody,

You cannot use a 16 MHz crystal instead of the 32 MHz.

I don't think you can get rid of the 32 KHz clock. I'll confirm that for you.

0 TA12012 over 12 years ago

TI__Mastermind 36385 points

Cody,

I am not sure its supported by the firmware, but technically the device would be able to do it. However, it is not a recommneded path to go down. The reason is that the RF XTAL oscillator consumes 1mA of current where the 32k LF oscillator only consumes 1uA. Therefore if you use this approach you will not have any thing near the battery life of your final product as you expect.

/TA

0 Chatto over 12 years ago in reply to TA12012

TI__Genius 12545 points

The 32 kHz crystal will be required. Also, the 32 MHz clock cannot be used to synthesize a 32 kHz clock, it is only used to calibrate the 32kHz RCOSC.

0 cody lohse over 12 years ago in reply to Chatto

Intellectual 650 points

Great, thank you for the quick answers.

Cody

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CC2570 32K Hz crystal optional?