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SparkFun RJ45 Breakout
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by Harold Pulcher

$ 1.95

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In stock 897 in stock
1.95 1+ units
1.85 10+ units
1.76 25+ units
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Description: RJ45 connectors are the kind that are used for Ethernet jacks, but they make great general purpose connectors when you need a lot of conductors. This is a small PCB that brings out the pins of the RJ45 connector to an in-line 0.1" footprint. Use with break-away headers for breadboarding or create your own RJ45 cable. Check the related items for Ethernet cable and connectors to go with it!

We used these connectors extensively in the Sound Squid demo!

Note: This is the PCB only - You can get the RJ45 connector in the related items below!

Dimensions: 0.7x0.8"


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Customer Comments

  • These are a really nice way to break out an RJ45 plug to 0.1" headers. Our FIRST Robotics team replaced most of our servo PWM cables with Cat 5 using these.
    Only comment: It would be nice it the board had two more holes in it so you could easily fasten it down to another surface.

  • FWIW, these breakout boards work perfectly with these very cost-effective RJ45 jacks from Jameco: https://www.jameco.com/webapp/wcs/stores/servlet/ProductDisplay?langId=-1&storeId=10001&productId=1537416&catalogId=10001&krypto=9x3mj8umRTpEiUpc4g3o46VWVeKoQOF4W0KGbu6hapIWj2QpMUWcjg%3D%3D&ddkey=https:StoreCatalogDrillDownView

  • I bought this along with the PRT-00643 connector and it seems that the breakout is 180 degrees out from the connector…. that is if pin 1 is the square pin. Or do I need to go back to school and learn my numbers and shapes?

  • As noted by others, the pin numbers are backwards if you assume that pin 1 is the square pin. This is related to the RJ45 jack that is used. If you use the SparkFun PRT-00643 which has the locking tab at the bottom, the pins will be reversed (the square pin is pin 8). If you use a jack with the locking tab at the top the pin numbers will be correct.

  • Will this Molex Jumber 2 Wire assembly fit with an rj-45 on this board? PRT-09918 https://www.sparkfun.com/products/9918

  • Works fine except the pin 1 designation (the square-shaped pad) is wrong, as noted by another commenter. The pins are in reverse: i.e. the pin 1 designation is actually designating pin 8.

  • Anyone know the maximum continuous current that the traces on this board can handle? In other words, are the traces >= 24 gauge wire?

  • It seems that the “Pin 1” indication (square pad) on this breakout is wrong, at least with the connector that you provide. I almost fried something in a PoE-setup :)

  • So how have people attached these to their projects?

  • What is pin 1?

  • Very nice! Easy assembly. Comes in handy for working with RJ45 for non Ethernet uses.

  • Very handy! I have older versions of these that work great.

  • This works great with both the Sparkfun MagJack and Pulse Magnetics J00-00XXNL parts.
    Wish that board included the LED pins, with grounds routed together and 0805 resistor footprints on the board. That would make this a plug-in solution, as it stands I have to route this stuff myself. Kinda a hassle.

  • I use them (with the RJ45 8-Pin Connector) more and more to connect two bread boards over some distance and it works great. I just wished there would be mounting holes, because the cable can pull quite a bit…

  • breakboarding?

Customer Reviews

4.7 out of 5

Based on 7 ratings:

5 star
4 star
3 star
2 star
1 star

1 of 1 found this helpful:

Works with RJ11 jack, with a bit of drilling

I needed a RJ11 breakout, but could not find one. This board, with a bit of minor hole enlarging, will work with the RJ11 6-Pin Connector - PRT-00132

1 of 1 found this helpful:

The Perfect Solution

The RJ45 Breakout Board allowed me to easily add a RJ45 Socket to my prototype.

1 of 1 found this helpful:

Good product with one caveat

The board quality is excellent. I find that all of the hole sizes are just fine, regardless of whether I am using a header strip or for Cat5 wire.

Just be aware that you pay attention to pin 1. Depending on the model of jack you use, the only way pin 1 can line up with the square pad is if the jack covers the header holes. If you mind where pin 1 is with respect to pin 1 on the jack, you are ok. (There are various comments concerning this in the comment section.)

I have several of them and continue to use them for various projects, just remark pin 1 and you are good to go.

1 of 1 found this helpful:

Works exactly as expected

Uses minimal space, much easier to use than the previous version. Not much more to be said.

Exactly what we were after.

Just what we needed and well made … that about sums it up.

Beware of the first pin

This breakout can be a little confusing, as the pin marked by the square is position 1 on the data sheet, but is actually pin 8 for an Ethernet cable - and the footprint used on this board does not match the RJ45 jack in the Sparkfun Eagle Library, which properly marks Ethernet pin 1 as the square pin, despite being position 8 on the data sheet.

Other than that, the quality is everything you would expect from Sparkfun. I would only ask for another mm or so on the 1" pins to add a screw header on the top side.

Super useful little gadget!

I’m using these little guys to add RJ-45 connectivity to Arduino projects that are using OneWire Type K thermocouplers. By setting up the data pins to hook into an RJ45, I can extend both the range of my thermocouplers through the use of standard network cables as well as clean up the Medusa’s Head of jumper wires that occurs during prototyping. I’ve got about 20 of these some with standard pins, and some with standard headers so I can plug and play lots of wired stuff all over the work bench. Great fun, great product. Need to order some more…