TPD12S521: TPD12S521

Barrie Mullins

Part Number: TPD12S521
Other Parts Discussed in Thread: TPD1E05U06

Hi, I am using a SIL9022A with a TI TPD12S521.

Note the SIL9022A states it does not require a pull on CEC with IO voltages of 3.3v. I have the IO at 3.3v on the SIL9022A driven from an AM437x.

HDMI CTS 1.4b

VCEC2 is required to be in the range 0.196v to 0.274v with VCEC1 in the range 2.88 to 3.63v.

Using the TPD12S521 as defined in the DS 27k pull, series diode to 3.3v, on CEC at the HDMI connector. With a 47k pull on CEC at the

SIL9022A (controller side).

Diode MMSD103T1G.

VCEC2 is greater than 0.274v on two test samples, under the test criteria defined by CTS 1.4b. Slightly over. 0.277v & 0.279v. Must meet this spec including tol on 27k pull to 3.3.

CEC pulled with a 27k 5% resistor to 3.3v source, & 1k pull down on CEC.

What is TI take on this issue?

I know the AM437x evm uses a different clamp (parallel) with this encoder, was there a particular reason why?

Thanks

Barrie

over 4 years ago

0 Ansel Song over 4 years ago

TI__Expert 3890 points

Hi Barrie,

For CEC, to block reverse current to the 3.3-V logic power rail, connect CEC_OUT to the 3.3-V logic level with a 27-kΩ pull-up resistor in series with a Schottky diode. 521 is only for protection, I think there is not any issue.

Regards,

Ansel

0 Barrie Mullins over 4 years ago in reply to Ansel Song

Prodigy 150 points

That's what I have.

Is this device HDMI CTS 1.4B compliant?

Test ID 7-15:CEC Line Degradation is what I am having issues with.

Thanks
Barrie

0 Ansel Song over 4 years ago in reply to Barrie Mullins

TI__Expert 3890 points

Did you test without TPD12S521?

Regards,

Ansel

0 Barrie Mullins over 4 years ago in reply to Ansel Song

Prodigy 150 points

Hi Ansel, yes, and CEC then met the voltage spec requirements.

Barrie

0 Ansel Song over 4 years ago in reply to Barrie Mullins

TI__Expert 3890 points

Hi Barrie,

Can you share the schematic and fail details? Or you can refer to https://www.ti.com/lit/an/slva747/slva747.pdf?ts=1623943090641&ref_url=https%253A%252F%252Fwww.google.com%252F#:~:text=2.7-,Test%20ID%207%2D15%3A%20CEC%20Line%20Degradation,devices%20it%20is%20attached%20to.

Ansel

0 Barrie Mullins over 4 years ago in reply to Ansel Song

Prodigy 150 points

Ansel, I've included part of the schematic showing the clamp and encoder.

I think I have an interaction between the SIL0922A and the clamp going on.

Thanks for the support.
Barrie

0 Ansel Song over 4 years ago in reply to Barrie Mullins

TI__Expert 3890 points

Hi Barrie,

Yes, I think you can also work with SIL0922A . And can you share the fails details?

Ansel

0 Barrie Mullins over 4 years ago in reply to Ansel Song

Prodigy 150 points

Ansel, I will raise a support ticket with Lattice as well.

Failure is VCEC2 is required to be in the range 0.196v to 0.274v with VCEC1 in the range 2.88 to 3.63v.
Removing TPD12S521 from the circuit, makes the design meet spec.

I am considering removing the CEC connections from the TPD12S521; can I just float the pins?
And using a TPD1E04U04DPYT for protection on the CEC line (assuming it doesn't create a problem), what do you think to that?
(I cannot find stock of TPD1E05U06, CEC is 3.3v).

Thanks
Barrie

0 Ansel Song over 4 years ago in reply to Barrie Mullins

TI__Expert 3890 points

Hi Barrie,

Yes, but it will lose ESD protection. I am just curious that I heard CEC failure first time for this device, I am not sure the test process is correct.

Regards,

Ansel

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TPD12S521: TPD12S521