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AFE5851 HP filter (register 33)

Vassili Ivanov40
Prodigy 200 points
Other Parts Discussed in Thread: AFE5851, AFE5851EVM, AFE5816, AFE5818

Hi, I am using all features of AFE5851 successfully, except digital high-pass filter. HP filter is set in registers 22[0], 22[4:1] and 33[0], 33[4:1]. Register 22 works for the channels 9-16(clear effect with the most aggressive filtering k=2). Register 33 has no effect on any channel (supposed to be channels 1-8?). Tested on multiple AFE5851 on multiple boards. Please confirm that datasheet (pages 19-20) is correct (is it really register 33?) and digital high-pass filter really works for all AFE channels.

Best Regards,

Vassili

  • 0
    TI__Mastermind 49666 points
    Hi Vassili,

    We have received your post regarding the AFE5851 and I have assigned it to the device application experts. They will get back to you with a response as soon as they can.
  • 0
    TI__Genius 12025 points

    Hello Vassili,

    Thank you for using our AFE5851 devices.

    Here we could show you how to set up the register 33 on AFE5851.

    1) We run this test using AFE5851EVM + TSW1400EVM.

    We input 2MHz signal to Channel 10 input pin on AFE5851 EVM (also using on-board 40MHz Clock) and use TSW1400 Board to capture the data from AFE5851 output.

    2) Set AFE5851 GUI register to be Address=33, Data=0x0004 to set CH9-16 HP filter Disabled.

    (Note: the data sheet shows the typo.)

    3) Run TSW1400 (High Speed Data Converter Pro) GUI and select "Channel 10/16"

    and press "Capture" button. We can see the HP filter is OFF right now.

    4) Set AFE5851 GUI register to be Address=33, Data=0x0005 to set CH9-16 HP filter enabled.

    5) Run TSW1400 (High Speed Data Converter Pro) GUI and select "Channel 10/16"

    and press "Capture" button. We can see the HP filter is ON right now.

    6) Please also view our new devices: AFE5818 and AFE5816 devices on the website.

    Thank you!

    Best regards,

    Chen

  • 0 in reply to Chen Kung
    Prodigy 200 points

    Thank you, Chen, 

    I solved the problem. In my own code I wrote originally x33 = d51 and x21 = d33, instead of d33 = x21 and d21 = x15.