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DS90UB953-Q1: Internal clock function

Jerry Zhao
Intellectual 1070 points
Part Number: DS90UB953-Q1

Hi Team,

Wish you have a nice day.

Currently my customer is using DS90UB953-Q1 in their design. And they want to use Non-Synchronous internal clock mode. There are some questions from their side and need your help to answer.

1. How to set 953 switch from external clock mode to Non-Synchronous internal clock mode? How about the stability and temperature drift of internal clock?

2. We mentioned in our datasheet that the CLKIN should be floating when we use internal clock, does this means we should remove external crystal oscillator? Is there any other thing should be pay attention to when we use external clock?

Thanks a lot.

BR 

Jerry

  • 0
    TI__Mastermind 26120 points

    Hi Jerry,

    Thank you for your questions.

    1. There are two ways to configure the 953 to operate in non-synchronous internal clock mode. The recommended method is to configure the mode pin to strap the device to the non-synchronous internal clock mode during power up. For details on this please see section 7.4.2 of the datasheet. If it is not possible to strap the 953 to the desired mode at power up, the mode can be changed using register 0x03. I will need to reach out to the internal team about the internal clock details. Is there a particular reason the customer wants to switch to non-synchronous internal clock mode? Are they concerned about the internal clock's reliability?

    2. Yes, when operating in nonsynchronous internal clock mode, the CLKIN pin should be left floating. So either remove or disconnect the external crystal oscillator. An additional note is that the CLK_OUT function is not supported when operating in internal clock mode.

    Regards,
    Darrah

  • 0 in reply to Darrah Merillat
    TI__Mastermind 26120 points

    Hi Jerry,

    Regarding the internal clock, this clock is relatively stable and does not vary much across temperature. The expected range is 24.2MHz (MIN) to 25.5MHz (MAX).