x557-at2 current consumption if only using 1 channel

[kh12]

Hello,

I am using an x557-at2 ethernet controller, but only need to use one of the channels. I am trying to design the power rails for the device, so I am mainly looking at the maximum currents which in the case of this device , the 0.83V rail goes up to 8A. Since I am only using one channel would it be fair to design the rails to 50% of the maximums? If not, could you give me some guidance on what current values I should be using to design the power rails? Thank you. 

p.s. I realize x557-at exists, however it is not easily purchasable right now and we therefore need to use the dual channel one.

-Karla

[Irwan_Intel]

Hi kh12,

Thank you for your post in the Intel Ethernet Community forum.

Please kindly allow us some time to look into the information, and we will respond to you shortly.

Additionally, You can find the most up-to-date documentation, schematics, and layout files on the Intel Resource and Design Center. Please note that accessing this documentation requires signing a Non-Disclosure Agreement (NDA). 

Visit the webpage below: Resource & Design Center for Development with Intel, register first then from the support menu type the documentation you are looking for.

https://www.intel.com/content/www/us/en/design/resource-design-center.html

Regards,

Irwan_Intel

[kh12]

Hello Irwan,

Do you have any updates to this question?

-Karla

[Irwan_Intel]

Hello kh12,

We regret to inform you that this issue is currently beyond the scope of our support. However, we are currently seeking a solution for you.

Regards,

Irwan_Intel

[Irwan_Intel]

Hi kh12,

From our Engineering update, Intel haven’t validated a design where only 1 port of the X557-AT2 is routed and used, so we cannot provide any guidance designing power supplies below the worst power consumption scenario. You will be wholly responsible for characterizing the max power consumption for the rails when only 1 port is routed for X557-AT2. That being said, the unrouted port will still be consuming idle power, probably similar to if it were a X557-AT in WoL mode.

 Also, please note the Datasheet only accounts for the electrical specifications of the ASIC itself and doesn’t account for passive components, board loss, and other overhead the power supply circuits will need to take into consideration. In the case of the 0.83v rail, our X557-AT2 reference designs and schematic checklists all indicate that power supply circuitry needs to accommodate up to 12A max, and not just the 8A max that the ASIC needs.

Regards,

Irwan_Intel

[kh12]

Hello Irwan,

A while ago I got a response from someone else on Intel implying the one port only usage would probably consume the same as the device with only 1 port. Which is why these assumptions were made...

I would have assumed there would be validation for how much each port consumes for the datasheet. I understand the unrouted port consuming idle power, but to design a power rail up to 12A for a device that might not even consume close to 8A because only a port is used feels like a big misrepresentation of power design..

-Karla

[kh12]

I guess I am wondering if you are really recommending we design this up to 12A, rather than assuming 1 port utilization + idle power consumption from both ports. In the datasheet I can see the following:

Note Low Power Mode (only one port active at 1 GbE) is characterized, is there no estimate for 10 GbE? can the same proportion be predicted? Meaning only one port for 1 GbE is 3.1W, but 1 GbE active is 3.6W, only 0.5W higher. 

[Irwan_Intel]

Hello kh12,

I'm following up to check if you have any additional questions or concerns regarding the previous post?

Please let me know if you need any further assistance.

Regards,

Irwan_Intel

[kh12]

Hello Irwan, 

Did you see my message above?

-Karla

[kh12]

Hello... any updates on this?

[Irwan_Intel]

Hello kh12,

Apologies for the delay, Engineering team have the following update.

Please check the respective SoC platform reference design for the platform you are using and schematic checklist for X557-AT2 attached to that SoC. 

From that, it should be evident the power supply circuitries need to provide enough current for worst-case max consumption by X557, plus what the passive components needs are in the design and margin overhead. 

For example, the 0.83v rail in the reference design recommends a 12A max current output, so as to provide 8A to X557-AT2 when both ports are actively pulling the max, plus 4A for the rest of the passive components in the board design. The prior comments were that it isn’t simply cutting the max current outputs in half just because only 1 port will be used on X557-AT2. 

Referring back to the 0.83v rail example, the extrapolation would be 1 port max current pull (~4A max), plus passive components, but also will need to account for the idle current pull of the unused port.

Reducing the 0.83v rail design with max current output of 6A may or may not work in your implementation, and it is crucial for you to thoroughly assess and consider all current draw and losses in your board design, not limited to the X557 component.

Regards,

Irwan_Intel

[Irwan_Intel]

Hello kh12,

I'm reaching out to see if you have any additional questions or concerns. If everything is resolved, we can proceed to close this thread.

Regards,

Irwan_Intel

[Irwan_Intel]

Hi kh12,

Please note that since we haven't received a response to our previous messages, we will be closing this request. If you have any more questions in the future, please feel free to ask a new question because this thread will no longer be monitored.

Regards,

Irwan_Intel