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Thank you for reading below my inquiry.

I'd like to use ADN4650 for Isolating TMDS (of HDMI by mainboard in computer), but ADN4650 is for isolating LVDS.

I found that TMDS's electrical specification is CML.

So, I need to converting circuits both CML->LVDS and LVDS->CML.

I'd like to designing compact circuit by passive parts like Resistor or Capacitor.

Motherboard(TMDS output of HDMI) -> (CML) -> Passive Circuit1 -> (LVDS)

-> ADN4650 -> (LVDS) -> Passive Circuit2 -> (CML) -> TV(TMDS input of HDMI)

Is it available for realizing this concept?

In Google, I found many solutions.

But, I want to find compact and proper solution for ADN4650.

How can I realize the schem for using ADN4650?

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• Hi,

Sorry, I didn't take enough time to correctly identify the sections of circuit I posted. The first one is actually LVDS to TMDS.

The second circuit has AC coupling on the TMDS input, then to introduce the LVDS biasing, the pull-up and pull-down on Din-. And to answer your Q1, now we can see it introduces a common mode due to Din+ being tied to Din- with 200 Ohm (split termination with common mode biasing could also be used, but the biasing on Din- should be just as effective).

Regarding Q2, our circuit assumed full isolation of a HDMI source. So on the isolated (cable) side, you need a power supply for isolator Vdd2s, as well as 5V/100 mA for HDMI to the sink. If you have sufficient 5V power on the source circuit, you can isolate using ADuM5000 x2. One ADuM5000 will provide the 5V/100 mA for the HDMI sink, and then the other will provide power for ADN4650 x2 and ADuM1250 x2. The latter will use a 5V supply, and the ADN4650 will require 2.5V on Vdd2 (ADP5302 will efficiently convert the voltage, allowing isoPower to be 5V->5V instead of the less efficient 5V->3.3V and then avoiding the LDO drop 3.3V to 2.5V using Vin2 to Vdd2 on ADN4650).

For Q3, but looking at the first circuit, I think actually R5/R7 may not be required. The CML input at the HDMI sink will reference both TMDS+ and TMDS- to 5V.

AC coupling is required as the CML/TMDS signals in HDMI are referenced to 5V, while LVDS receiver and driver operate at lower voltages, and either require a common mode around 1.2V on the input, or provide one on the output.

• Hi,

Sorry, I didn't take enough time to correctly identify the sections of circuit I posted. The first one is actually LVDS to TMDS.

The second circuit has AC coupling on the TMDS input, then to introduce the LVDS biasing, the pull-up and pull-down on Din-. And to answer your Q1, now we can see it introduces a common mode due to Din+ being tied to Din- with 200 Ohm (split termination with common mode biasing could also be used, but the biasing on Din- should be just as effective).

Regarding Q2, our circuit assumed full isolation of a HDMI source. So on the isolated (cable) side, you need a power supply for isolator Vdd2s, as well as 5V/100 mA for HDMI to the sink. If you have sufficient 5V power on the source circuit, you can isolate using ADuM5000 x2. One ADuM5000 will provide the 5V/100 mA for the HDMI sink, and then the other will provide power for ADN4650 x2 and ADuM1250 x2. The latter will use a 5V supply, and the ADN4650 will require 2.5V on Vdd2 (ADP5302 will efficiently convert the voltage, allowing isoPower to be 5V->5V instead of the less efficient 5V->3.3V and then avoiding the LDO drop 3.3V to 2.5V using Vin2 to Vdd2 on ADN4650).

For Q3, but looking at the first circuit, I think actually R5/R7 may not be required. The CML input at the HDMI sink will reference both TMDS+ and TMDS- to 5V.

AC coupling is required as the CML/TMDS signals in HDMI are referenced to 5V, while LVDS receiver and driver operate at lower voltages, and either require a common mode around 1.2V on the input, or provide one on the output.

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