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TSW1400EVM: Noise problem at testing TSW1400EVM, DAC56575

Bae YoungYoon
Prodigy 30 points

Part Number: TSW1400EVM

Hello,

I am doing test with tsw1400evm, dac5675a board and High Speed Data Converter Pro v5.00 (GUI).

I followed instruction of Neeraj Gill's DAC5675A EVM Quick Start Guide (2/15/2017), and then I got same result with Guide's result at last month.

and I do the same test excatly like one month ago's situation but there is output including Noise.

Let me show you my test result(1.One month ago's test result, 2.Now test result)

(1.)

(2.)

I input 399.36Mhz Data rate, both are sine waves in same conditions.

the purple sine wave and green wave must same but it is not.

the blue signal wave is single ended input wave of DAC5675a's LVDS chip.

you can see there are a lot of noise at blue signal wave.

I checked all of Lines, Connectors, Probes, SMA Cables, but i don't have idea about the noise problem except inside board problem possibility.

please give me some advice and help.

thanks.

  

  • 0
    TI__Mastermind 20541 points

    Hi Bae,

    From your description above if everything is the same as before but you are seeing distorted output signal. I am think there might be setup and hold timing issue. Can you try to the adjust the delay of clock signal going to DAC vs signal going to the TSW1400 EVM and see if there is any improvement in output.

    Regards,

    Neeraj 

  • 0 in reply to Neeraj Gill
    Prodigy 30 points

    thanks for replying, Neeraj.

    I could think about delay of clock adjusting because of your mention.

    your mention was very effective.

    I want to say thank you for solving problems but I have new question.

    so if you okay, Let me explain my new question.

    1. In HSDC Pro, I edited sawtooth wave for Importing as 'Load External Pattern Files' by text files. (the lowest value is 0, the highest value is 16000)

    and I loaded my text files and then the wave's frequency was okay, but amplitude was reduced 1/4 peek value in DAC time domain window.

    Can you tell me about the relation of text file's peek value and Imported external file's peek value?   

    2. and it's actual output looks like operating 2's and offset bin reversed. please give me an example or explain of principle of 2's and offset bin.

    3. I have purpose that tsw1400 and dac5675a use as voltage output without transformer. so i refer to 'Passive Terminations for Current Output DACs's 3.1 Single-ended output, No transformer Required'.

    there is figure 6 including the voltage source as 5V. Should I use 5V unrelated to AVDD 3.3V in DAC5675A? 

    4. and i want to know about processing(some of equation) of adjusting resistor combination in same page. in above datasheet said, Excel spreadsheet is available but i can't find in ti.com.

    can you tell me where the spreadsheet is?

  • 0 in reply to Bae YoungYoon
    TI__Mastermind 20541 points

    Hi Bae,

    1. HSDCpro software takes 16 bit data and data is MSB justified, the data you are importing HSDCpro is 14 bit. To make your data MSB justified you will have to shift you data left by 2 which same as multiplying the data  by 4.

    2. Please select offset binary option in HSDCpro it should fix your issue.

    3. Use figure 24a from the datasheet.

    4. Here is termination you will need for DAC5675A without the transformer.

    Regards,

    Neeraj

  • 0 in reply to Neeraj Gill
    Prodigy 30 points

    Hi Neeraj,

    I solved all problems because of your helps.

    Thank you Neeraj. Very much.

    You are my savior.

    Thank you again.

    Goodbye.

    Regards,

    Bae