DS90UH929-Q1: Additional buffer on DDC line with EEPROM

Nao

Part Number: DS90UH929-Q1
Other Parts Discussed in Thread: TCA9517

Hi, E2E member

Our customer is considering to add the buffer(TCA9517) in DDC line.
Schematic is here.
Ser IC-EEPROM-Buffer-circuit_181016.pdf

Their design can select with buffer or without buffer in DDC line.

They have 2 options to connect the buffer. This schematic is option2.
1. They connect a buffer between HDMI port and EEPROM.
2. They connect a buffer between EEPROM and DS90UH929.

Which one is better?

Regards,
Nao

over 5 years ago

0 Palaniappan Manickam over 5 years ago

TI__Genius 10475 points

Nao,
What is the purpose of using this buffer? For actual customer schematics please do not post on E2E since this is a public forum.

0 Nao over 5 years ago in reply to Palaniappan Manickam

Genius 4905 points

Hi, Palaniappan

The purpose of using this buffer is improvement of signal quality.
I already got the permission from our customer to post it on E2E.

Regards,
Nao

0 Darryl Jeong over 5 years ago

TI__Expert 4210 points

Is the loading that bad that a buffer is needed?
2 would be better if the loading is heavy between EEPROM and DS90UH929.

0 Nao over 5 years ago in reply to Darryl Jeong

Genius 4905 points

Hi, Darryl

Thank you for your reply.
As you can see from this schematic, the buffer(TCA9517) is used for when there is any problems.
Especially, they thinks the loading is NOT bad at this stage.

They have 2 options to connect the buffer.
1. They connect a buffer between HDMI port and EEPROM.
2. They connect a buffer between EEPROM and DS90UH929.

Which one is better if there are any problems of signal quality?

Regards,
Nao

0 Darryl Jeong over 5 years ago in reply to Nao

TI__Expert 4210 points

Hi Nao-san,
I would guess the signal quality would be better on the board between the EEPROM and DS90UH929 if designed properly.
There could be degredation from the HDMI port and the EEPROM due to coming in thru the cable.
My best guess option would be #1.

0 Nao over 5 years ago in reply to Darryl Jeong

Genius 4905 points

Hi, Darryl

Thank you for your feedback.

Regards,
Nao

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DS90UH929-Q1: Additional buffer on DDC line with EEPROM