DP83867CR: DP83867CRRGZT Current mode

Taito Takemura

Part Number: DP83867CR
Other Parts Discussed in Thread: DP83869

Tool/software:

HI team,

My customer is considering using the "DP83867CRRGZT" in conjunction with the LAN Port "7499151120" manufactured by Würth Elektronik for 1000BASE-T communication. The LAN port "7499151120" requires current mode, but I could not find any information in the DP83867CRRGZT data sheet on whether current mode is supported. Could you please answer the following questions regarding current mode?

Questions

- Could you please tell me if DP83867CRRGZT can be used in the above way? If not, I would like you to recommend an alternative PHY.

- Could you provide a typical circuit diagram example for current mode connection for reference?

- (My Question) Could you please provide me with an explanatory document regarding the PHY current mode itself?

RJ45 Connector

- Product Homepage https://www.we-online.com/de/components/products/WE-LAN-RJ45?sq=7499151120#7499151120

- Datasheet https://www.we-online.com/components/products/datasheet/7499151120.pdf

They selected the two-tiered type to reduce the mounting area.

Thank you for your help.

Regards,

Taito Takemura

2 months ago

0 Gerome Cacho 2 months ago

TI__Mastermind 31455 points

Hello,

I do not see anywhere in the WURTH datasheet that this magnetic needs a current mode MDI driver. DP83867 is a voltage mode driver (a tell-tale way to determine is the presence/absence of external termination on the line, such as our DP83822). However, looking at this transformer, it is suggested to not use this component due to center tap shorting between channels.

For typical application circuit, please refer to datasheet of DP83867.

Sincerely,

Gerome

0 Taito Takemura 2 months ago in reply to Gerome Cacho

TI__Intellectual 2160 points

Hi Gerome,

Gerome Cacho said:
However, looking at this transformer, it is suggested to not use this component due to center tap shorting between channels.

Thank you for letting me know.

Just to be sure, could you please recommend a current-mode compatible 1000BASE-T Ethernet PHY device to replace the DP83867CR?

Regards,

Taito Takemrua

0 Gerome Cacho 2 months ago in reply to Taito Takemura

TI__Mastermind 31455 points

Hello,

We do not have a current-mode compatible 1G PHY to replace DP83867. DP83867, DP83869, and DP83561 are our 1G PHYs and all are voltage mode devices. Can I ask why customer needs current mode specifically? What PHY are they trying to replace with TI PHY?

Sincerely,

Gerome

0 Taito Takemura 2 months ago in reply to Gerome Cacho

TI__Intellectual 2160 points

Hi Gerome,

Thank you for your answer.

Is it correct to understand that current mode is sometimes used for low-speed communication, but voltage mode is the mainstream for high-speed communication over 1G?

Also, could you please tell me in what cases current mode is recommended?

Regards,

Taito Takemura

0 Gerome Cacho 2 months ago in reply to Taito Takemura

TI__Mastermind 31455 points

Hello,

I would say that the implementation is independent of the speed. We have 10/100 PHYs in our portfolio that support current mode driver, and others that support voltage mode driver. Our same 1G PHYs (voltage mode) are capable of 10/100 speed without changing the MDI circuitry. Each implementation is unique, and customer is free to choose either or based on what is available in our portfolio.

Sincerely,

Gerome

0 Taito Takemura 2 months ago in reply to Gerome Cacho

TI__Intellectual 2160 points

Hi Gerome,

Thank you for your help.

Could you please tell me your recommended combination of a two-level LAN connector and PHY for 1000BASE-T communication to reduce mounting area, such as LAN Port "7499151120" manufactured by Würth Elektronik?

Regards,

Taito Takemura

+1 Gerome Cacho 2 months ago in reply to Taito Takemura

TI__Mastermind 31455 points

Hello,

We do not have explicit recommendation for two level connector. However, we do give guidance for field/customer on how to interpret specifications and what our PHY needs: https://e2e.ti.com/support/interface-group/interface/f/interface-forum/1161575/faq-dp83867e-how-do-i-choose-magnetics-for-my-industrial-phy?tisearch=e2e-sitesearch&keymatch=%25252525252525252520user%2525252525252525253A462093#

Sincerely,

Gerome

0 Taito Takemura 1 month ago in reply to Gerome Cacho

TI__Intellectual 2160 points

Hello,

Gerome Cacho said:
We do not have explicit recommendation for two level connector

Could you please introduce me to a TI engineer who is knowledgeable about PHY connectors and who might have a solution to this two-stage connector issue?

Thank you for your help.

Regards,

Taito Takemura

0 Gerome Cacho 1 month ago in reply to Taito Takemura

TI__Mastermind 31455 points

Hi Taito,

We do not have a specific expert for this topic. However, our recommendation is still relevant regardless if single connector or dual connector. I would recommend checking with vendor what components they have available and cross-referencing against our FAQ.

Sincerely,

Gerome

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DP83867CR: DP83867CRRGZT Current mode