AM6442: Treating LBCLKO (N21) pin

Hideaki Matsumoto

Part Number: AM6442

Hi,

My customer needs to know as soon as possible about treating LBCLKO of OSPI on AM6442, because they have to fix their board design soon.

They’ve read the chapter 4.4.1 OSPI, xSPI, QSPI, SPI Boot in the TRM about the treating LBCLKO (Pin N21) when OSPI is used in Primary Boot Mode with the highest speed (using DQS), and there is the following description. However, the pin N21 is used as GPIO instead of LBCLKO on their prototype board.

In their use case also, do they have to follow the following when using OSPI at the highest speed in Primary Boot Mode ? The pin N21 itself must strictly adhere to the following ?

Or in the only case of pin N21 is selected as LBCLKO, the following should be required ?

If the use of the pin N21 itself is prohibited, they want to remove the resistor and leave it open. Will it be prohibited even leaving the wiring pattern as well?

Regards,

Hideaki

over 2 years ago

0 Kallikuppa Sreenivasa over 2 years ago

TI__Guru**** 203830 points

Hello Hideaki,

Thank you for the query.

We are recommending a pull for any SoC pad that has a trace connected.

In case you do not want to use N21 and want to provision, i would recommend adding an additional pull down near to the PAD.

You can mount the pulldown when not used and De populate the pulldown when you use N21 for whatever application you want to use.

Regards,

Sreenivasa

0 Hideaki Matsumoto over 2 years ago in reply to Kallikuppa Sreenivasa

TI__Genius 9540 points

Hi Sreenivasa,

Thank you for answering the question. OK, understood that LBCLO pin can be a no connect, but additional pull down is recommended.

As this pin N21 (LBCLKO) is not used, they want to use this pin as GPIO. Is it possible ?

They're using OSPI FLASH with xSPI mode, DDR mode, using DQS and OSPI_CLK @133.333MHz. As the following high-speed OSPI mode described in the first paragraph below.

They're considering to use the pin N21 as GPIO by configuring like below.

Thanks and regards,
Hideaki

0 Kallikuppa Sreenivasa over 2 years ago in reply to Hideaki Matsumoto

TI__Guru**** 203830 points

Hello Hideaki,

Thank you for the additional queries.

I will reassign the thread to the OSPI expert to comment.

Regards,

Sreenivasa

0 Hideaki Matsumoto over 2 years ago in reply to Kallikuppa Sreenivasa

TI__Genius 9540 points

Hi Sreenivasa,

Could you please give us an answer ?

Regards,
Hideaki

0 Kallikuppa Sreenivasa over 2 years ago in reply to Hideaki Matsumoto

TI__Guru**** 203830 points

Hello Hideaki,

Thank you for following.

I have assigned the query to the flash expert.

I will request the expert to reply offline.

Regards,

Sreenivasa

0 Lucas Bowe over 2 years ago in reply to Kallikuppa Sreenivasa

TI__Expert 5845 points

Hey Hideaki,

We are still discussing the question you've posed about using that pin as a GPIO and whether or not the design restrictions still apply. I will come back with an answer as soon as possible.

Sincerely,

Lucas

0 Hideaki Matsumoto over 2 years ago in reply to Lucas Bowe

TI__Genius 9540 points

Hi Lucas,

Thank you for looking into this inquiry. Did you get any result ? The customer needs your answer as soon as possible, because they have to fix the board design. It would be appreciated if we can receive your answer as soon as possible.

Thanks and regards,

Hideaki

+1 Lucas Bowe over 2 years ago in reply to Hideaki Matsumoto

TI__Expert 5845 points

Greetings Hideaki,

No information yet and I cannot provide any estimate as to when. The answer to this situation is not straightforward to get unfortunately, so if the customer is pressed for time it would be better to use an alternative pin as a GPIO and leave N21 without any trace connected.

Sincerely,

Lucas

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AM6442: Treating LBCLKO (N21) pin