DS250DF230: DS250DF230

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user6207997

Replies: 5

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Part Number: DS250DF230

Hi:

I'm using DS250DF230 in the design, and I'm doing the PRBS test. The link under test is like this:

322.265625MHz ->  CABLE -> Retimer (10.3125Gbps) -> oscilloscope

I want to use the retimer to generate PRBS. But after I configured the registers, there're no signal outputs. My configuration sequence is shown below:

Referenced from Programmer's guide(SNLU182D)

// Configuration
0xFC, 0x01 , 0xFF 
0xFF, 0x03 , 0x03
0x0A, 0x0C , 0x0C

0x60, 0x90 , 0xFF 
0x61, 0xB3 , 0xFF 
0x62, 0x90 , 0xFF 
0x63, 0xB3 , 0xFF 
0x64, 0xFF , 0xFF 
0x09, 0x04 , 0x04 
0x18, 0x10 , 0x70

0x1E, 0x00 , 0x10
0x0A, 0x00 , 0x0C
 

//PRBS gen
0x2E, 0x04 , 0x04 
0x30, 0x01 , 0x03
0x1E, 0x10 , 0x10
0x79, 0x00 , 0x20
0x79, 0x20 , 0x20 
0x30, 0x00 , 0x08
0x30, 0x08 , 0x08 
0xA5, 0x80 , 0xE0

Any advice will be appreciated, thanks!

• DS250DF230
• # configuration

Prodigy 40 points

user6207997

• Oct 26, 2020 10:41 AM
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5 Replies

• Genius 11895 points

  

  Rodrigo Natal

  

  • Oct 27, 2020 4:15 PM

  Hi,

  Can you confirm whether you are using CAL_CLK_IN = 25MHz on your board?

  Cordially,

  Rodrigo Natal

  HSSC Applications Engineer

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• Prodigy 40 points

  

  user6207997

  

  • Oct 27, 2020 11:40 PM

  In reply to Rodrigo Natal:

  Hi, Rodrigo

   I have confirmed that I'm using CAL_CLK_IN = 25MHz(50ppm) on my board.

  Regards,

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• Genius 11895 points

  

  Rodrigo Natal

  

  • Oct 28, 2020 12:32 AM

  In reply to user6207997:

  Hi,

  What values are you observing for the channel registers below on the retimer channel in question that you are working to configure as PRBS generator?

  • 0x02
  • 0x27
  • 0x28
  • 0x78
  • 0x8F

  Cordially,

  Rodrigo Natal

  HSSC Applications Engineer

   

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• Prodigy 40 points

  

  user6207997

  

  • Oct 29, 2020 7:47 AM

  In reply to Rodrigo Natal:

  Hi,

  I observed the below channel register values.

    0x02 -> 0x00

    0x27 -> 0x00

    0x28 -> 0x00

    0x78 -> 0x20

    0x8F -> 0xEA

  Regards,

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• Genius 11895 points

  

  Rodrigo Natal

  

  • Oct 29, 2020 5:20 PM

  In reply to user6207997:

  Hi,

  The retimer CDR does not appear to be locking to your 322.265625MHz reference signal. Some additional suggestions

  • Can you try the next sub-rate frequency up, 644.53125MHz?
  • What signal amplitude are you using, can you try increasing it?
  • Try manually forcing CTLE = 0x00 on this PRBS generator channel. See below.

  Table. Set CTLE Boost Value

  STEP	SHARED/ CHANNEL REGISTER SET	OPERATION	REGISTER ADDRESS [HEX]	REGISTER VALUE [HEX]	WRITE MASK [HEX]	COMMENT
  1	Channel	Write	2D	08	08	Enable CTLE boost override
  2	Channel	Write	03	00	FF	Set CTLE boost to 0x00.

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