ADC12DJ2700: Initial Setup

Hiroshi Katsunaga

Mastermind 6480 points

Part Number: ADC12DJ2700
Other Parts Discussed in Thread: LMK04826

Hello,

My customer has a question about ADC12DJ2700.

[Q]

Please tell me the proper initial setup sequence for JESD204B perspective.

They are using the periodic SYSREF signal with DC coupling.

Device Clock and SYSREF is generating with LMK04826.

They especially want to know how to set the SYSREF_RECV_EN and SYSREF_PROC_EN.

If SYSREF_RECV_EN=1 and SYSREF_PROC_EN=1, JESD204B was not align.

If SYSREF_RECV_EN=1 and SYSREF_PROC_EN=0, JESD204B was align.

Therefore please tell me the proper initial setup sequence for JESD204B perspective.

Best Regards,

Hiroshi Katsunaga

over 6 years ago

0 Vijayendra Varma Siddamsetty over 6 years ago

TI__Genius 11115 points

Hi Hiroshi,

We are looking into your customer's question and will get back to you.

Regards,

Vijay

0 Hiroshi Katsunaga over 6 years ago in reply to Vijayendra Varma Siddamsetty

Mastermind 6480 points

Hi Vijay,

Thank you for your response.

OK, I will wait your feedback.

Best Regards,

Hiroshi Katsunaga

0 Hiroshi Katsunaga over 6 years ago in reply to Hiroshi Katsunaga

Mastermind 6480 points

Hi Vijay,

Do you have any update ?

Best Regards,

Hiroshi Katsunaga

0 Rob Reeder over 6 years ago

TI__Mastermind 45670 points

Hi Hiroshi-san,

Is the SYSREF_LVPECL_EN set to 0 as well? In either case specified above?

This should also be set in order to DC couple the Sysref.

Please let me know.

Thx,

Rob

0 Hiroshi Katsunaga over 6 years ago in reply to Rob Reeder

Mastermind 6480 points

Hi Rob,

Thank you for your response.

They set the SYSREF_LVPECL_EN to 1, because it is written as follows in the D/S.

The termination changes to 50 Ω to ground on each input pin (SYSREF+ and SYSREF–) and can be DC-coupled when SYSREF_LVPECL_EN is set to 1.

This input is not self-biased when SYSREF_LVPECL_EN is set to 1 and must be biased externally to the input common-mode voltage range provided in the Recommended Operating Conditions table.

Is this description wrong ?

Best Regards,

Hiroshi Katsunaga

0 Rob Reeder over 6 years ago in reply to Hiroshi Katsunaga

TI__Mastermind 45670 points

Hi Hiroshi-san,

Everything seems correct to me. I will need to check this out in the lab.

I will work on this and get you an answer early next week.

Regards,

Rob

0 Rob Reeder over 6 years ago in reply to Rob Reeder

TI__Mastermind 45670 points

Hi Hiroshi-san,

After further looking into this, for DC coupling the SYSREF the customer will need to use one of the following SYSREF alignment schemes outlined in the datasheet.

It can be done manually as described on page 43 or Automatically as described on page 44.

page 43: 7.3.5.3.1 SYSREF Position Detector and Sampling Position Selection (SYSREF Windowing)

page 44: 7.3.5.3.2 Automatic SYSREF Calibration

Hopefully this will help.

Regards,

Rob

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ADC12DJ2700: Initial Setup