Power consumption

The EtherTen combines an Uno-equivalent Arduino-compatible board and Wiznet-based Ethernet support, along with a microSD card slot and Power-over-Ethernet support. [Product page]
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seans
Posts: 1
Joined: Mon Jun 03, 2013 11:51 pm

Power consumption

Post by seans » Tue Jun 04, 2013 12:20 am

Hi all,

I'm trying to resolve an issue related to power consumption on an EtherTen board:

I have a battery powered application running on this board (two sensors logging to the micro SD) but the current draw is quite high at around 220mA without anything connected.

I can't find any specs that state what the overall consumption is, but I'm assuming the ethernet capability (not used in this instance) contributes significantly to it.

Power management code doesn't seem to make any difference, so I've cut the 3v trace to the Wiznet chip, but that hasn't made any appreciable difference either. And that's tested with the Blink sketch!

Does anyone have any ideas or suggestions as to what I can do?

Cheers,
Sean

hads
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Joined: Tue May 01, 2012 3:58 am

Re: Power consumption

Post by hads » Tue Jun 04, 2013 1:37 am

I'm subscribing as I'm interested to hear what the outcome is here.

angusgr
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Re: Power consumption

Post by angusgr » Tue Jun 04, 2013 5:22 am

Hi Sean,

I get similar values to you with an unmodified EtherTen. With Blink I measure 220mA if I power the board with 10V through the onboard linear regulator, 150-180mA if I power it directly to 5V in. Even holding the whole board (including the W5100 chip) in reset mode doesn't drop this by much.

When you say you cut the 3.3V VCC trace, there are unfortunately a number of 3.3V VCC pins - multiple pins split across two 3.3V rails (analog and digital.) Are you sure you got them all? It may not be necessary to cut the analog rail off but I think you'll definitely need to hit all the digital pins.

Looking at the board in EAGLE it should be possible to cut both the analog and digital rails if necessary with two cuts on the bottom of the board, but you'll also disconnect the 3.3V comparator voltage for the automatic input selection, so you'll have to either airwire that or live with USB power permanently selected. Let me know if you'd like me to provide more details.

If you didn't need the 3.3V for the MicroSD I'd suggest removing the 3.3V regulator entirely, but I suppose that kind of defeats the purpose of having an EtherTen at all!

The Wiznet W5100 is unfortunately simply not a low power chip - it runs comparatively hot and doesn't have any low power modes designed into it.

Hope this helps,

Angus

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