• State Resolved
  • Locked Locked
  • Replies 1 reply
  • Subscribers 46 subscribers
  • Views 416 views
  • Users 0 members are here
Support feedback
Options
Options
Related

This thread has been locked.

If you have a related question, please click the "Ask a related question" button in the top right corner. The newly created question will be automatically linked to this question.

ADS42LB49EVM: Sine wave test pattern does not match the one on datasheet

Mahmoud Zannerni62
Intellectual 655 points
Part Number: ADS42LB49EVM
Other Parts Discussed in Thread: ADS42LB49

Hello,

I am using ADS42LB49EVM Rev B and the generated 8 points sine wave is:

0 5792 8191 5792 0 -5793 -8192 -5793

This does not match the values on the datasheet, could you clarify please.

"In the ADS42LB49, data are a repetitive sequence of the following eight numbers, forming a sine-wave in twos complement format: 0, 2399, 8192, 13984, 16383, 13984, 8192, and 2399."

In data sheet it says twos complement and the values are unsigned, I found this a bit confusing!

Also, for deskew pattern the value in datasheet is 3AAAh and in reality it is 2AAAh and I think this is the correct value?!

Thanks,

Mahmoud

  • 0
    TI__Guru* 91947 points

    Mahmoud,

    The sine wave comes in 2’s complement format, which means the MSB is inverted.

    To convert a straight-binary format (which the pattern is called out in the data sheet) into 2s complement format, you just need to flip the MSB.

    This is equivalent to subtracting 8192 when data was smaller than 8192, and adding 8192 what data was greater than 8192.

    There is a typo in the data sheet regarding the deskew pattern. The value should be 2AAAh like you mention.

    Regards,

    Jim