Is it possible for someone to review a simple 2 page schematic with the ADV7611 and ADV7612 for possible
issues? If yes, please provide an email address or method to send the schematic since it is considered confidential.
If you attach them here, great. Else let me know and I'll contact you off line.
Hopefully this works….I got a delivery failure when I tried replying to your response from 2 weeks ago.
Please look at the ADV7611 and 7612 on pages 3 and 4. The regulators are on page 12.
Senior Field Applications Engineer
2100 Evergreen Blvd
Duluth, GA 30096
Got it. I'll get back later today on this.
1) D1 needs to be low leakage diode like MA3X704
2) Double check Y1 loading caps, recalc per hardware manual formulas
3) If you are designing for a 50 Ohm PCB, 51 Ohm port resistors are a bit high but should work. I use 33 Ohm for 50 Ohm boards.
4) Rail inductors can be replaced with murata NFM21PC105B1A3D. Smaller in 0805 package. Just a suggestion to save board space.
5) Sufficient rail decoupling caps, good
6) Put 100 Ohm series resistor in +5V_HDMI_IN in front of ADV7612. Will protect RX!_5V pin from ESD hits on the DDC_5V pin.
7) I'm a bit confused about U28. If the board is not powered you can't access the EDID memory through the HDMI connector since U28 won't have power. Why are you or'ing +5V and +5V_HDMI_IN into +5V_EDID then. Normally we use two 3 pin jumpers on our reference boards to do this. Suggest replacing U28 with two 3 pin jumpers.
1) Why R154, R157, C188. The ADV7511 is expecting a CMOS level clock. Usually series resistor at source is sufficient. Just no pop it.
2) Suggest current limiting the +5V on the HDMI connector. If anybody does something like shorting the 5V pin to ground on the HDMI connector you might burn up your board. General design rule is that if you supply any power off board, it needs to be current limited it some how. Our older video eval. boards didn't do this. The new ones do.
1) C42,43 missing ground symbol
1) use a solid plane under the parts.
2) Follow guidelines here HDMI Layout Guideline
3) I can check the layout also when you get it done.
Let me know if you need anything else.
Thanks so much for the quick and detailed response. Please see my customers response and question at the end of his email below.
Any clarification on the EEPROM would be appreciated.
Thank you for feedback. I agree with all except item 7. The reference design show ‘OR’ 2 voltage sources together and that is what I did. I don’t quite understand the reason myself.
On page 1, you can see the EEPROM power as EDID_PWR,
On page 6, you can see the source for EDID_PWR:
The reference design has 4 HDMI connectors. So it looks like when the board is OFF, the external device can still read the EDID EEPROM via the HDMI connector since it provides HDMI_xx_5v. Is this a true requirement?
There's no requirement for the source to be able to read the EDID when the board is powered off, unless you have this specific requirement. We just use two 3 pin jumpers to implement what U28 does.
So depending on the jumper installation you have 3 options
1) no jumpers -- use the ADV7612 internal EDID
2) jumpers to HDMI connector -- EDID powered by and readable by the source
3) jumpers to the I2C bus -- EDID power by the board and programmable by the processor
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