DP83822IF: Link is still established in low BER condition

Toshihiro Watanabe

Part Number: DP83822IF

Hello,

I saw AFBR-5803 used in reference design. Please let me ask if DP83822IF keep link established when AFBR-5803 used for fiber module.

In AFBR-5803 datasheet, deassert level is written below. It will be BER rate may become 10e-2. Does DP83822IF keep link in this low BER condtion?

DP83822IF becomes not re-established if SD doesn't connect LED_1 except for software reset. We worry DP83822IF can't establish link again If SD is assert but link is broken situation occurs.

Do we think ok this situation doesn't occur in low BER condition?

"The maximum value will occur when the input optical power is either –45 dBm average or when the input optical power yields a BER of 10–2 or larger, whichever power is higher."

Best regards,

Toshihiro Watanabe

over 5 years ago

0 Vibhu Vanjari over 5 years ago

TI__Genius 11900 points

Hello Toshihiro-san,

The behavior of what you described is driven by IEEE standards. If you have further questions, please explain the issue.

Thanks,

Vibhu

0 Toshihiro Watanabe over 5 years ago in reply to Vibhu Vanjari

TI__Genius 10235 points

Hello Vibhu-san,

The customer just concern if DP83822IF became not re-established link because link is broken under worse BER condition. The customer system can't accept software reset in working status.

I understand as IEEE specified how much BER rate PHY needs to sustain link. Is my understanding correct?

I think 10E-2 BER is no issue for DP83822IF. Is my understanding correct?

Best regards,

Toshihiro Watanabe

0 Vibhu Vanjari over 5 years ago in reply to Toshihiro Watanabe

TI__Genius 11900 points

Hello Toshihiro-san,

The PHY meets the requirement specified in the IEEE standard.

Thanks,

Vibhu

0 Toshihiro Watanabe over 5 years ago in reply to Vibhu Vanjari

TI__Genius 10235 points

Hello Vibhu-san,

Would you advise us where we could check IEEE standard? I looked some but couldn't find it.

Best regards,

Toshihiro Watanabe

0 Vibhu Vanjari over 5 years ago in reply to Toshihiro Watanabe

TI__Genius 11900 points

Hello Toshihiro-san,

I will need to check with the team on what the time interval is on this before link is dropped, I assume this is what you are asking:

Given the BER of 10E-2, how long does the link stay established? Is this correct?

Thanks,

Vibhu

0 Toshihiro Watanabe over 5 years ago in reply to Vibhu Vanjari

TI__Genius 10235 points

Hello Vibhu-san,

I read as the opto-module de-assert opto power is -45dBm or BER becomes 10e-2.

When link is established with enough power but power is getting weaker and weaker, opto power might become above condition.

If link is broken under this condition, DP83822IF requires soft RESET. This soft RESET is unwilling operation.

So they would like to know if DP83822IF brokes link under low opto-power condition.

If not broken, they don't need software RESET because link doesn't be broken.

Best regards,

Toshihiro Watanabe

0 Vibhu Vanjari over 5 years ago in reply to Toshihiro Watanabe

TI__Genius 11900 points

Hello Toshihiro-san,

I expect that at BER 10E-2 the link cannot be maintained and you will have to restart the linkup procedure once again.

If you have access to an EVM please try this using the specific opto-module/power you are referring to.

Thanks,

Vibhu

0 Toshihiro Watanabe over 5 years ago in reply to Vibhu Vanjari

TI__Genius 10235 points

Hello Vibhu-san,

Thank you for your estimation. I think DP83822IF may be needed software reset because SD still assert and link may be broken.

How can we know above situation occurs? If this condition occurs, when should we apply software reset?

Best regards,

Toshihiro Watanabe

0 Vibhu Vanjari over 5 years ago in reply to Toshihiro Watanabe

TI__Genius 11900 points

Hello Toshihiro-san,

Please see if the link is being broken on the EVM.

You can use the signal from LED/GPIO pin reflecting link status as an input to determine when to apply software reset.

Thanks,

Vibhu

0 Toshihiro Watanabe over 5 years ago in reply to Vibhu Vanjari

TI__Genius 10235 points

Hello Vibhu-san,

When 100BASE-FX mode, does LED_1 pin input information is set to 0x469[9] bit?

If so, LED_1 is still assert by 0x469[9] but LInk is broken by 0x0001[2], we can know software reset is required. Is my understanding correct?

Best regards,

Toshihiro Watanabe

0 Toshihiro Watanabe over 5 years ago in reply to Toshihiro Watanabe

TI__Genius 10235 points

Hello Vibhu-san,

When 100BASE-FX mode, does LED_1 pin input information is set to 0x469[9] bit?

Best regards,

Toshihiro Watanabe

0 Vibhu Vanjari over 5 years ago in reply to Toshihiro Watanabe

TI__Genius 11900 points

Hello Toshi-san,

I meant configure LED_0 to be on for link, off for no link, using register 0x0019 or strap configuration.

Monitor this signal to trigger reset as needed.

In 100BASE-FX LED_1 is signal detection pin connected to optical transceiver.

Thanks,

Vibhu

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DP83822IF: Link is still established in low BER condition