SN65DP159: SN65DP159RGZR - DDC line from the source is connected directly to the sink

Yoav Benita

Part Number: SN65DP159

Hi,

I want to use this device as HDMI Retimer only. Because my source supply the DDC signals as 5V, I don't need this device to level shift the lines from 3.3V to 5V. Can I connect this lines directly to the sink (SCL, SDA and HPD)? If yes, the DDC input's and output's should be floating?

Thank's.

over 3 years ago

0 David (ASIC) Liu over 3 years ago

TI__Guru**** 177081 points

Hi,

In this case,

1. SDA_SRC and SCL_SRC must be pulled to ground.

2. HPD_SRC can be left floating

3. HPD_SNK must be connected to the HPD link between the source and the sink

4. SDA_SNK and SCL_SNK must be connected to the DDC link between the source and the sink.

Thanks

David

0 Yoav Benita over 3 years ago in reply to David (ASIC) Liu

Intellectual 285 points

Thank you David.

How can I control the DDC SNK lines voltage ?

If I need it in 3.3V (I2C and HPD), what should I do?

0 David (ASIC) Liu over 3 years ago in reply to Yoav Benita

TI__Guru**** 177081 points

Hi,

You can use an external level shifter to shift between 3.3V and 5V, https://www.ti.com/lit/ds/symlink/tpd5s116.pdf.

Thanks

David

0 Yoav Benita over 3 years ago in reply to David (ASIC) Liu

Intellectual 285 points

Hi,

I will try to explain my question again.

I need the HPD_SNK, SDA_SNK, SCL_SNK lines to be 3.3V.

In the datasheet mentioned that the HPD and I2C voltage range is –0.3V to 6V.
Why I need an external level shifter to make this lines in 3.3V level?
What is the parameter that determines this output voltages?

The I2C standard is Open-Drain, maybe for this lines an external Pullup to 3.3V is enough? If yes, What about the HPD ?

0 David (ASIC) Liu over 3 years ago in reply to Yoav Benita

TI__Guru**** 177081 points

Hi,

I was thinking this is a HDMI design. So the DDC bus voltage needs to be between 4.5V and 5.5V to be HDMI compliant.

The VIH of the SDA_SNK and SCL_SNK is 3V, so SDA_SNK and SCL_SNK can support 3.3V, but you need to make sure you have margin to stay above the 3V min VIH.

Thanks

David

0 Yoav Benita over 3 years ago in reply to David (ASIC) Liu

Intellectual 285 points

Thank you David.

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SN65DP159: SN65DP159RGZR - DDC line from the source is connected directly to the sink