DP83TC811R-Q1: Impact on now following the power up timing

May

Part Number: DP83TC811R-Q1

Hi,

Customer want to know more about the power up timing of the device.

Basically, they need to know what exactly mean by T5.5 and T5.8.

1. "Post power-up stabilization-time prior to MDC preamble for register access"
2. "PAM3 IDLE Stream from power-up (Master Mode)"

3.The impact if not following the power up timing requirement above (What will happen when not following the power up timing)

Customer have different understanding in the power timing requirement, can you confirm which is the correct one.

1. The 60ms is the max delay time from power stabilize to MDC preamble for register access. For example, if T5.5 = 200ms then it will be NOK.

2. The 60ms is the time needed for the DP83TC811R-Q1 to get ready before MDC preamble for register access. For example, if T5.5 = 200ms then it will be OK.

Thank you in advance.

Regards,
Maynard

over 2 years ago

0 Kallikuppa Sreenivasa over 2 years ago

TI__Guru** 123088 points

Hello Maynard,

Thank you for the query.

The T5.5 mentioned in the datasheet is the minimum value. 200ms should not be a concern.

Regarding the T5.8, the timing may be important to adhere to the protocol. Any specific use case that makes you ask the question on the T5.8 ?

Regards,

Sreenivasa

0 May over 2 years ago in reply to Kallikuppa Sreenivasa

TI__Genius 9880 points

Hi Sreenivasa,

Thank you for your response, customer want to to know whether is it same as Q1 above, the 60ms is the minimum time instead of maximum time. According to them, their current system's T5.8 is greater than 60ms, is this ok? is there any impact?

Regards,
Maynard

0 Kallikuppa Sreenivasa over 2 years ago in reply to May

TI__Guru** 123088 points

Hello Maynard,

T5.8 is greater than 60ms, is this ok? The timing would depend on the configurations.

Ae you using the EVM or custom board.

Regards,

Sreenivaa

0 Zhonghui Xu over 2 years ago in reply to Kallikuppa Sreenivasa

TI__Expert 5445 points

Hi Sreenivasa,

Sorry to interrupt. I'm also interested in the question of Yago.

Please confirm that the 60ms of T5.8 is the minimum time instead of maximum time.is it right?

Thanks.

Best regards,

0 Kallikuppa Sreenivasa over 2 years ago in reply to Zhonghui Xu

TI__Guru** 123088 points

Hello Maynard,

How is the 60ms being measured. Would it be possible to provide a scope capture?

Regards,

Sreenivasa

0 May over 2 years ago in reply to Kallikuppa Sreenivasa

TI__Genius 9880 points

Hi Sreeniva,

Just received response from customer, below is the details.

I am using custom board. But is T5.8 a maximum time or minimum time. If our T5.8 is greater than the value specified in the datasheet, is it okay?

Regards,
Maynard

0 Kallikuppa Sreenivasa over 2 years ago in reply to May

TI__Guru** 123088 points

Hello Maynard,

Thank you for the inputs.

How is the 60ms being measured. Would it be possible to provide a scope capture?

This should be measured after the supplies are stable.

Regards,

Sreenivasa

0 May over 2 years ago in reply to Kallikuppa Sreenivasa

TI__Genius 9880 points

Hi Sreenivasa,

According to customer, they comparing the time between VDDA and TRD_P and it is measured after the supply is stable. They want to know if this the correct step, if not is there a guide on how to do it.

According to them, the waveform is same as the one attached in the datasheet T5.8

Regards,
Maynard

0 Kallikuppa Sreenivasa over 2 years ago in reply to May

TI__Guru** 123088 points

Hello Maynard,

Thank you for the response.

The measurements looks fine. Can you please confirm the status of reset_n when he measurements are being done.

I also assume the device is configured in master mode.

Is there a slave connected ?

Also can you please ask customer to measure T6.5.

Regards,

Sreenivasa

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

TI__Guru** 123088 points

Hello Maynard,

Do you have some updates for me.

Regards,

Sreenivasa

0 May over 2 years ago in reply to Kallikuppa Sreenivasa

TI__Genius 9880 points

Hi Sreenivasa,

The customer did not yet replied.

Will update once there is an update.

Thank you.

Regards,
Maynard

0 Kallikuppa Sreenivasa over 2 years ago in reply to May

TI__Guru** 123088 points

Hello Maynard,

Noted and thank you.

Regards,

Sreenivasa

0 PY (Pengyu) Song over 2 years ago in reply to Kallikuppa Sreenivasa

TI__Expert 5860 points

Hi,

Sorry for the additional question - is there any plan to update datasheet to change T5.5 spec from maximum to minimum? There is a post discussing this before.

https://e2e.ti.com/support/interface-group/interface/f/interface-forum/882817/dp83tc811r-q1-the-power-up-timing-of-dp83tc811r-q1?tisearch=e2e-sitesearch&keymatch=DP83TC811R%2520T5.5#