SN75DP139: I2C_EN pin setting for DVI

When I2C is low, the Internal I2C register is disabled and not readable when the TMDS port is
selected indicating that the connector being used is DVI.

Hello Brian,

I repeat the question. Can we also set I2C_EN pin high for DVI application? Of course, as the customer's circuit is fixed to "L" by design, but there is no way to avoid the indefinite situation(L/H).

Regards,

Masa

Masa:

       There are some difference between DVI output and HDMI output. When I2C_EN is high, output is changed to TMDS output, so DVI can not work.

Regards

brian

Hi Brian,

Are there any other parameters that change when I2C_EN is in H/L state other than rize/fall time? (Datasheet 6.1)

I thought that if rise/fall time is the only parameter that changes depending on the I2C_EN status, then DVI would work in HDMI mode (I2C_EN = H) since DVI is slower than HDMI, but can't it?

Regards,

Masa

Masa-san

The DP139 also has an internal I2C slave (adaptor) that gets enabled when I2C_EN is H. I don't know how the source will respond if it tries to read the I2C slave and see the DP139 is a HDMI adapter. 

Thanks

David

Hello David-san,

When the SN75DP139 is connected to the DVI connector on the display, the master display will communicate with the SN75DP139 as if it is connected to DVI, and we thought that the SN75DP139 as the slave would not spontaneously notify the master display that it is in HDMI mode. What do you think?

Regards,

Masa

Hello David-san,

I received an additional question. From 7.5.1 in the datasheet, if HDMI is not selected in CPU and Display, the I2C Slave register of DP139 will not work; if DVI is selected in CPU and Display, it can work regardless of I2C_EN status, do you think?

Regards,

Masa

Masa-san

The DP139 I2C registers accessibility only depend on the state of I2C_EN pin as shown below. It does not depend on whether the source is HDMI or DVI.

 Thanks

David

Hello David-san,

In a previous response you said the following.

”I don't know how the source will respond if it tries to read the I2C slave and see the DP139 is a HDMI adapter.”

When I2C_EN is high, does this mean that the IC may not work when used in DVI mode?

Regards,

Masa

Masa-san

”I don't know how the source will respond if it tries to read the I2C slave and see the DP139 is a HDMI adapter.” "It" in this case refers to the source.

So the DP139 will work in both HDMI and DVI mode, but it is up to the source if the source read the Adapter as HDMI instead DVI.

Thanks

David

Hi David-san,

In other words, if the source is DVI, can I2C_EN work either High or Low?

Regards,

Masa