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CC2340R5: TCXO usage

Akihiko Fujinaka
Expert 3465 points
Part Number: CC2340R5
Other Parts Discussed in Thread: SYSCONFIG

Hello expert,

Our customer wants to use TCXO instead of XTAL.

In this usage,  they have some questions.

1) How to connect ?  TCXO output should be connected to X48P and X48N should be open , right?

2) SW setting?  I found TCXOTYPE register setting in HFXTCTL Register. This bit should be set accordingly to the TCXO output type, CMOS or clipped-sine, right?

3) Are there any other point they should take care?

4) Which power line of CC2340R5 is used for X48P ?

Regards,

A.Fujinaka

  • 0
    TI__Guru**** 171044 points

    Fujinaka-san,

    Thank you for your inquiry.

    1) That is the correct connection scheme. Our device supports

    2) That is correct. Also, there are two other bits on this same register that need to be set: TCXOMODE and EN

    One important aspect, though: at this time I see no formal software support for TCXO, which should be configured in the Sysconfig --> Device Configuration module. In this case, please inform your customer this procedure is not thoroughly validated yet.

    4) I am not sure if I understand your question. Are you asking which VDDS or VDDR pins are connected to the Clock subsystem? All power pins on the CC240R5 are interconnected.

    Hope this helps,

    Rafael

  • 0 in reply to desouza
    TI__Expert 3465 points

    Hello Rafael,

    Regarding #4,  Yes, your understanding for my question is correct.
    They want to know which voltage should be input to X48P, so want to confirm which power pin is connected in ternally.

    Regards,

    A.Fujinaka 

  • 0 in reply to Akihiko Fujinaka
    TI__Expert 3465 points

    Hello Rafael,

    Also, you mentioned customer should set EN, is that bit0?

    So , totally, customer should set TCXOMODE= bit7, TCXOTYPE = bit6 and EN= bit0?

    Regards,

    A.Fujinaka

  • 0 in reply to Akihiko Fujinaka
    TI__Guru**** 171044 points

    Fujinaka-san,

    Akihiko Fujinaka said:
    They want to know which voltage should be input to X48P, so want to confirm which power pin is connected in ternally.

    I checked some internal resources and verified the TCXO output must range from 0 to VDDR.

    Akihiko Fujinaka said:
    So , totally, customer should set TCXOMODE= bit7, TCXOTYPE = bit6 and EN= bit0?

    Yes, these three bits have to be properly configured and set.

    I reiterate that we do not have official support for TCXO in our SDK at this time, thus please inform your customer to use it at their own risk.

    Best regards,

    Rafael

  • 0
    TI__Expert 3465 points

    Hello desouza,

    If they use the Clipped-sine wave / DC-coupled TCXO,

    Will AC coupling support for TCXO output and CC2340R5 X48P input (means it can be input the internal DC bias?)  

    Or the direct connection is only supported ?

    Regards,

    A.Fujinaka

  • 0 in reply to Akihiko Fujinaka
    TI__Guru**** 171044 points

    Fujinaka-san,

    I am not sure I understand your question. Do you want to use a clock signal that varies around the GND (0V) level?

    As I mentioned above, the X48P pin accepts entries from 0V to VDDR.

    An AC coupled sinewave will range from -VDDR/2 to +VDDR/2 therefore, outside of the range of the X48P pin.

    Please let me know if you meant something different.

    Hope this helps,

    Rafael