AM6548: Hardware Problem of Silicon Rev2.0 to Rev2.1 migration

Hello Hwang

Thank you for the query.

Are all the boards of the same version, could you please read and share the proc number on the boards.

Regards,

Sreenivasa

Thanks

Rev2.0 Silicon

"AM6580AACD"

Rev2.1 Silicon

"AM6548BACDXEAF"

Best regards 

Hwang

Hello Hwang

Thank you for the inputs.

I am looking for the board hardware version. You can read that on the board - not on any device.

Are all the boards of the same version, could you please read and share the proc number (board revision) on the boards.

Regards,

Sreenivasa

Hello Mr. Kallkupa.

Thank you for your rapid response.

We made 5 boards at the same time and process.

2 are Rev2.1 and 3 are Rev2.0. 3 Rev2.0 works well but 2 Rev2.1 are not.

I changed AM6548 Rev2.1 chip using the good working Rev2.0 board.

But, same as previous result.

Best regards

Hwang

Hello Hwang

Thank you.

Sorry for the confusion. You have 3 types of custom boards.

For 2 types of boards, you do not see any issue when you change silicon 2.0 to 2.1 

On 1 type of board, silicon revision chip 2.0 works but not 2.1 . 

In terms of hardware design, you believe all the 3 boards are similar.

Please confirm if the understanding matches your thought.

Regards,

Sreenivasa

Mr. Kallkupa.

Yes, absolutely correct for your description.

and also the 3 boards are very similar except I/O designs. 

Hwang.

Hello Hwang

Thank you.

I changed AM6548 Rev2.1 chip using the good working Rev2.0 board. But, same as previous result.

You swapped the non-working board device rev 2.1 to a working board which had 2.0 silicon working and found that the board did not work.

Is that correct?

Any thoughts on the load cap you have on the board, are they similar to the other 2 boards? Are the crystal load caps in the range specified in the datasheet.

Regards,

Sreenivasa

Hello Mr. Kallkupa.

Thank you.

I swapped new Rev2.1 chip to good working Rev2.0 board.

The WKUP OSC0 waveform is different from good working borad.

Good woking board's amplitude is as large as 1.8V  sinewave form.

But. bad board's amplitude is about half and distorted like a clipped sine wave.

So, I checked the voltage of VDDA_WKUP. The voltage is 1.8V 

Best regards.

Hwang.

P.S.

I am a korean, so I can't write english very well.

Hello Hwang

Thank you.

The communication looks good, no worries.

The 2.1 device did not work on the first assembled board and later when changed to another 2.0 working board, the 2.1 device did not work.

In summary the same 2.1 device did not work on both the boards. I assume the 2.0 device works on both boards.

How about the load cap value?

Regards,

Sreenivasa

Hello Mr. Kallkupa.

The crystal cap Cf1 and Cf2 value is 18pF. It is same value of reference design.

And, I also changed the value to 33pF because the crystal load capcitance is 18pF.

The waveform is slightly changed and distorted.

and the optional Rbias resistor changed to 1M, Open, 510K ohm but the result are same.

The crystal P/N is 445I23D25M00000 CTS.

Best regardes.

Hwang.

Hello Hwang

Thank you.

18pF is the specified crystal load cap. We specify a load cap of 12-24pF.

Did you try with 24 or 27pF load cap. 33 is high considering ~4 pf of stray cap.

18pF; looks low but seems to be working. Can you also try with a 15pF.

Do you have an Rd?

Regards,

Sreenivasa

Hello Mr. Kallkupa.

Rd is 0 ohm, I will try your recommendations.

But. I dought the BGA rework. So. today I sent the board to external BGA professional.

After get the board, I will try again and send the result to you.

Thank you very much for your consideration.

Best regards.

Hwang.

Hello Hwang

Thank you. for the inputs and noted.

Regards,

Sreenivasa

Hello Mr. Kallkupa.

After BGA rework, the board works fine.

By virtue of you. 

Thank you again for your good assistance.

Good luck.

Hwang.