SparkFun RJ45 MagJack Breakout

This is the SparkFun RJ45 MagJack Breakout, a simple board that will provide you with a way to put an ethernet port into your breadboard. The SparkFun RJ45 MagJack Breakout is the same one found in our very own mbed Starter Kit and breaks out each pin from the ethernet jack. This rev of the breakout is equipped with the RJ45 MagJack connector already soldered to the board which mean you no longer need to solder the connector to the board yourself or worrying about buying them separately!

The on-board RJ45 ethernet jack has a built in transformer (magnetics), status LEDs, and shielding all for better reliability when you use it. As stated before, each pin from the RJ45 MagJack has been broken out, including: P1-P8 (Pins 1-8), Y+ (Yellow LED Positive), Y- (Yellow LED Negative), G+ (Green LED Positive), G- (Green LED Negative), and SH (Shield).

RJ45 8-Pin Connector / RJ45 Breakout

SparkFun RJ45 MagJack Breakout Product Help and Resources

Core Skill: Soldering

This skill defines how difficult the soldering is on a particular product. It might be a couple simple solder joints, or require special reflow tools.

1 Soldering

Skill Level: Noob - Some basic soldering is required, but it is limited to a just a few pins, basic through-hole soldering, and couple (if any) polarized components. A basic soldering iron is all you should need.
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Core Skill: Electrical Prototyping

If it requires power, you need to know how much, what all the pins do, and how to hook it up. You may need to reference datasheets, schematics, and know the ins and outs of electronics.

2 Electrical Prototyping

Skill Level: Rookie - You may be required to know a bit more about the component, such as orientation, or how to hook it up, in addition to power requirements. You will need to understand polarized components.
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Looking for answers to technical questions?

We welcome your comments and suggestions below. However, if you are looking for solutions to technical questions please see our Technical Assistance page.

  • maser228 / about 7 years ago / 3

    The description says this is for Ethernet only, but not why. A "MagJack" has transformers built into the jack itself. As a result, this breakout won't work for a non-Ethernet application where the pins need to be isolated from each other, and connected directly to the cable's wires. With a meter, pins 1-2-3 and 4-5-6 on this breakout look like dead shorts to each other. This is correct for Ethernet, but not for any other applications.

  • Member #568814 / about 3 years ago / 1

    Will this work for PoE? I have a singled ended cable that needs to pass through a small hole. Once I soldered the P1-8 wires to the MagJack breakout and connect onwards there is no connection.

    • CF / about 3 years ago / 1

      Please keep in mind that this RJ45 MagJack Breakout is for Ethernet networks only. If all you need is a simple RJ45 breakout, we recommend soldering an RJ45 8-Pin Connector to our SparkFun RJ45 Breakout as a solution. RJ45 8-Pin Connector RJ45 Breakout

  • davolfman / about 6 years ago / 1

    Am I reading the datasheet right in that P3 and P6 are the middle-of-the-winding contacts that show up in, for example, the typical application circuit for a TI TPS237x PoE chip?

  • Member #738818 / about 8 years ago / 1

    The schematic PDF seems to be unavailable from your CDN. Getting a blank page.

Customer Reviews

2.5 out of 5

Based on 2 ratings:

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1 of 1 found this helpful:

Good product -- nice and small

This product is a single RJ45 jack breakout PCB. I will not comment on its MagJack properties - including the transformers which I presume are for Power over Ethernet applications. I did not buy it for that feature which others may find useful. I wanted a small RJ45 breakout PCB that I could mount and that would allow me access to the 8 standard RJ45 pins. This product achieves smallness and offers access to each of these 8 primary RJ45 pins. That satisfied my use. it has other solder pins which I assume are for the transformer and LEDs and that may interest others with more sophisticated needs.

What I like about this product: 1. small 2. 2 clearance holes for mounting this PCB 3. Breakout solder pad access to all internal RJ45 jack pins.
4. well labeled.
5. attractive red PCB color. (just kidding. don't care about the color). 6. Build quality looks good.

I looked around and this was one of the smallest RJ45 breakout PCBs I found. So, good for them. I will buy them for my application.

I would like to see them make PCBs with 2, 3, and 4 RJ45 jacks with solder pad breakouts in which the RJ45 jacks are NOT in parallel but in which each Jack is individually addressable. That I could not yet find.

Overall, seems like a good example of a RJ45 breakout PCB.

1 of 2 found this helpful:

Doesn't Work

Pin 1 & 2 are shorted. I'm not sure if I'm just misunderstanding the product, but I wanted a simple way to connect to the pinout of a cat5 cable. You can not achieve that with this product.

Note: Please keep in mind that this RJ45 MagJack Breakout is for Ethernet networks only. If all you need is a simple RJ45 breakout, we recommend soldering an RJ45 8-Pin Connector to our SparkFun RJ45 Breakout as a solution.