TLK6201EA receiver input termination

Hiroshi Sato

Other Parts Discussed in Thread: TLK6201EA, DS25BR400, DS42BR400

0027.TLK6201EA_question20121228.pptHello,

Our customer now evaluating cable equalizer device. They are trying with TLK6201EA and DS25BR400, and they will decide whichi is better for them.

And, I have a question. In TLK6201EA, does it have a receiver input termination circuit which is same as DS25BR400 ?

I attached file for help to understand this question.

Thanks and best regards,

Hiroshi Sato

over 11 years ago

0 Michael Peffers over 11 years ago

TI__Mastermind 20820 points

Hi Hiroshi,

The TLK6201EA has single ended 50Ohm terminations to GND at the input.

Regards,

Mike

0 Hiroshi Sato over 11 years ago in reply to Michael Peffers

Expert 2590 points

Hello Mike-san,

Thank you for your replying.

Now, the customer has made evaluation circuit for both device and asking us to confirm them.

(about coupling capacitor, line impedance, and the other points if you find)

Could you check the attached circuit and give us comment , please ?

Thanks and best regards,

Hiroshi

3187.Transceiver_connection.xls

0 Michael Peffers over 11 years ago in reply to Hiroshi Sato

TI__Mastermind 20820 points

Hi Hiroshi,

I will take a look at this later on this week when I have some available bandwidth. Also, I have to loop in another apps team because i do not support the DS parts.

Regards,

Mike

0 Nasser Mohammadi over 11 years ago in reply to Michael Peffers

TI__Guru* 88835 points

Hi Hiroshi,

I looked at the DS42BR400 schematic that you had enclosed. DS42 has internal 100 ohm termination and a weak bias(1.3V common mode). You can AC couple or DC couple as you have shown in the schematic.

I believe since the output is LVDS and DS42 input is CML but with weak bias you can DC couple between LVDS output and CML input of the DS42. If we had strong bias(for example 50 ohm to Vcc) then we would have advised AC coupling vs DC coupling.

Regards,,nasser

0 Hiroshi Sato over 11 years ago in reply to Nasser Mohammadi

Expert 2590 points

Hello Nasser-san,

Thank you for your advice.

Today, the customer has started BER test with their circuit(attached before). The data rate is 3Gbps. DS42BR400 worked good, but TLK6201EA was not.

They think coupling capacitor is required between signal source(LVDS) and TLK6201 input.

Otherwise, they don't cleary know whether coupling capacitor are required at the others(between TLK output and connector, connector and next TLK input ).

About TLK device, I'll wait feedback from Mike-san. Thank you.

Best regards,

Hiroshi.

0 Michael Peffers over 11 years ago in reply to Hiroshi Sato

TI__Mastermind 20820 points

Hi Hiroshi,

The inputs and outputs of the TLK6201 need to be AC coupled for proper operation. Other than that the schematic looks good.

Regards,

Mike

0 Hiroshi Sato over 11 years ago in reply to Michael Peffers

Expert 2590 points

_{Hi Mke,}

Thank you for your comment.

I'll ask the customer to evaluate with coupling capacitors for all input and output at TLK6201.

Thanks and best regards,

Hiroshi

0 Nasser Mohammadi over 10 years ago in reply to Hiroshi Sato

TI__Guru* 88835 points

Hiroshi-San,

After running some test in DC couple mode using DS42BR400, our recommendation is to DC couple as long as the common mode voltage is about 1.3V. At other common mode voltages like 2V or 2.5V we recommend AC coupling since this is the most reliable solution. Based on our test and evaluation this is the correct approach and would enable a reliable/long lasting design.

Regards,,nasser

0 Hiroshi Sato over 10 years ago in reply to Nasser Mohammadi

Expert 2590 points

Hello Nasser-san,

Thank you for your information.

I'll talk to concerned people about this.

thanks and best regards,

Hiro

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TLK6201EA receiver input termination