Ethernet Shield

Using Arduino Networking, Protocols, and Devices
1

Hi,
I am using the ethernet shield as shown in the photo.

What i would like to know is why the Vin pin on ethernet shield is marked a 9V, when it should be marked a Vin.

Can I provide input power to the UNO through this pin or not.

Why labelled as 9V ?
Thanks

819er16jPXL.AC_SL1500
819er16jPXL.AC_SL15001429×1012 228 KB

2

Welcome to the forum

At a guess the components on the Ethernet shield have a maximum voltage rating of 9V

3

Thank you for a quick response. so I understand I cannot connect 12 v power supply.

Thanks

4

probably - best not to try.

And anyway there is no good reason to power your Arduino with 12V. You put lots of pressure on the component that needs to transform into heat the ~(12 -5 =) 7V x whatever Amps you consume... 9V is plenty already.

ideally you should ask sunfounder for the detailed specs

5

the Vin pin (marked 9V here) goes directly to to board under the shield. it is not used by the shield. Ethernet shield is powered from the 5 V pin.

6

I am using a 12v power because I am driving some relays & servos.

So I can use the Vin (9V) pin on shield to power the board with a 12v power.

7

I would not

the Wiznet W5100 Ethernet chip alone draws 150mA. Add the Arduino and a few stuff around it and you might be well above 200mA

the Arduino Uno has 1117 LDO voltage regulator and with a 12V input the LDO is dissipating too much heat if you draw 200mA (see Question about using a 5V relais with Arduino UNO - #3 by fobi123)

That's probably why they mention 9V, that will put less stress on the LDO voltage regulator

8

I've used the Sunfounder W5100 shield and two LED drawing 10mA each with an UNO and 12V input via the barrel jack. No problems.

9

yes. it is the same input as the barrel jack.

10

OK so that's not the reason for the 9V marking then :slight_smile:

11

As @Juraj pointed out, that pin is not used by the shield. It's just connects to whatever the shield is plugged into. Why it's 9V, who knows.

12

Agreed, but the shield is powered through the 5V pin, so through the LDO, right ?

if the shield burns 150mA minimum, those 150mA have been provided by the Arduino under the shield which also draws at least 50mA.

So my point was that those 200mA at 12V seems dangerously close to (above) the high bar for the LDO in terms of heat dissipation.

if you had only 9V on the Jack (so that Vin pin would be 9V) then the LDO would have less power to dissipate, possibly within reason.

just a guess, I'm a software guy...

13

You are making quite a few assumptions.

  • the shield burns 150mA minimum

  • 200mA at 12V seems dangerously close to (above) the high bar for the LDO in terms of heat dissipation.

Is it plugged into an UNO, a mega or a clone, or standalone?

14

well let's call that an educated guess as I did a bit of research before posting:

OP mentioned an UNO in his first post

Of course it's just a guess

15

All true but how does sunfounder know what I'm going to plug this into.

16

may be they went for typical use case where the shield is plugged on top of a UNO and powered through the 5V pin. this gig draws 200mA which seems high for the LDO if you power through the Jack with 12V so may be they wanted to draw attention to that... (or the lawyers had them write that - CYA strategy...)

I don't know. just speculation

17

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