TMDS181: HPD and I2C Connections verification

I looked over you schematic and I am wondering why you are connecting HPD2_SINK to the HDMI in connector and not connecting HDMI_IN_HPD to the HDMI in connector?

Hi Michael,

Could you please suggest me the better connections for the same?

Thanks & Regards,
Nanjunda M

Hi,

The schematics connection was made considering the voltage level support of the SCL, SDA and HPD pins.

In the datasheet, Figure 35, shows a connection example, in which the HPD is said to be connected to 5V, whether that circuitry is necessary?

Also, the SCL and SDA are it correct to retain in the same state as in the schematics? (not as in Figure 35 of datasheet)

Please let me know ASAP.

Thanks & Regards,

Nanjunda M

Hi Michael,

Could you please respond.

Thanks & Regards,

Nanjunda M

The schematic looks correct. The SCL and SDA resistors are correct if you are not using DDC snoop.

Whether The source to Connections are correct?
I wonder why they have suggested (Figure 35) to connect direclty to the sink side!

Please let me know.

Thanks & Regards,
Nanjunda M

from the datasheet "The TMDS181 drives the HPD signal to 3.3 V, which meets requirements, but if 5 V HPD signaling is required, the two circuits shown in Figure 35 are required. As sources are not consistent in implementing all aspects of the DDC link, TI recommends to configure the TMDS181 as per Figure 35."

Hello Nanjunda,

It looks like your application has the TMDS181 located on the same PCB as the sink and you are implementing DDC in snoop mode and HPD in snoop mode. Is that correct?

If you are using DDC snoop mode SDA_SCR and SCL_SCR should be pulled low and HPD_SRC can be left unconnected.

Regards,
JMMN

Hi,

Can you please review the connections, I updated as per the Figure 35 in the datasheet. 

SCHEMATIC1_HDMI_INPUT_updated.pdf

I would like to operate the TMDS181 in normal mode.

Please suggest me, if any changes needed in the above-updated schematics.

Thanks & Regards,

Nanjunda M

Hi JMMN,

Is this really necessary?

Thanks & Regards,
Nanjunda M

Yes, we have seen cases where noise in the system on the unconnected pins has been interrupted as signaling by the TMDS181 and has resulted in the TMDS181 holding the I2C bus indefinitely.

Regards,
JMMN