EYE on NPI - Bel Fuse 1xN port MagJack and specialty ICMs

Adafruit Industries

This week's EYE ON NPI is as ethereal as it is magical: it's Bel Fuse's 1xN port MagJack and specialty ICMs (https://www.digikey.com/en/product-highlight/b/bel-fuse/1xn-port-magjack-and-specialty-icms). These are specially made Ethernet and Ethernet-USB combo jacks that have magnetic transformers inside to make integration with your Ethernet PHY (https://en.wikipedia.org/wiki/Ethernet_physical_layer) in order to communicate on the network. MagJacks make designs smaller, and less noisy - they're a great way to simplify your next Ethernet design and get it to market faster! Wireless this, 5G that - what we sometimes need are WIRES! Wired networking is much reliable than wireless, and can go far distances with no loss of signal strength. Particularly as you can also put power over the same wires for nodes that need no other cabling, Ethernet is a reliable networking standard - don't discount it just because of its age! One nice benefit of it is you don't have to do SSID/password setup, it's truly plug and play. Three things are required to add Ethernet. First is a microcontroller or microcomputer that has built in Ethernet Medium Access Control (https://en.wikipedia.org/wiki/Medium_access_control), the low level packet forming technology. Some chips have this built in, such as the ESP32 (https://www.digikey.com/short/dz5pv22m) - or you can use a companion chip like the WIZ5xxx series (https://www.digikey.com/en/supplier-centers/wiznet) that can be controlled over SPI. Then, to get onto a network, you'll want the ubiquitous mechanical RJ-45 connector (https://www.digikey.com/short/t28834zr) that will lead to Cat-5 or Cat-6 cable (https://www.digikey.com/short/pnjh3t8d). In between, the signal levels need to be isolated and converted to the +-2.5V differential signal. To do that we need what is colloquially referred to as the 'magnetics': a cluster of transformers and chokes that will make the signal differential, isolate the PHY from the outside world and also reduce the risk of outside spikes and shocks. Both the Wiznet and ESP32 datasheets, for example, have example wiring to help you identify the right configuration. Note that not all chips have the same magnetics impedances / configurations: it depends on the output signal and impedance. Second, this is separate than PoE magnetics (https://www.adafruit.com/product/3847) which are separate from the data transfer. If you don't care about optimizing board size and complexity, you can always use external magnetics with a plain jack. Bel has a full selection of dozens of magnetics for any configuration you may need (https://www.belfuse.com/product-detail/icm-s-discrete-lan-magnetics). For example the Seeed Ethernet shield (https://www.digikey.com/short/70cvntbm) uses this technique because the PCBA is so big they have space to spare. However, when you want to keep your board compact, you can upgrade your design to use one of Bel Fuse's 1xN port MagJacks. (https://www.digikey.com/en/product-highlight/b/bel-fuse/1xn-port-magjack-and-specialty-icms) MagJacks provide two big benefits (https://www.digikey.com/en/product-highlight/b/bel-fuse/1xn-port-magjack-and-specialty-icms): one they're smaller than separate magnetics/jacks and second, the magnetics get enclosed in the metal shell of the jack which provides some EMI shielding. For example, we used a combo-jack on the Ethernet Featherwing (https://www.digikey.com/short/9w49r80j) to keep the design single-sided. Which is why we were excited to see the Bel Fuse MagJacks pop up on https://www.digikey.com/new - they're a trusted component we've used before. For this week's EYE ON NPI, DigiKey is highlighting a selection of the new Bel Fuse MagJacks, with dozens of options available (https://www.digikey.com/en/product-highlight/b/bel-fuse/1xn-port-magjack-and-specialty-icms). There's classic horizontal ones with LEDs (https://www.digikey.com/en/products/detail/bel-fuse-inc/P01-0002-01/25588398). Vertical ones! (https://www.digikey.com/en/products/detail/bel-fuse-inc/P01-1AF2-01/25588382) Countersunken for low clearances (https://www.digikey.com/short/5b9mb454) As well as some nifty combo-units that contain both USB type A and Ethernet. (https://www.digikey.com/en/products/detail/bel-fuse-inc/P01-3CG3-01/25588395) Just make sure that the internal magnetics match your chipset's needs before selecting it for integration. DigiKey is in the process of stocking all the varieties, but if you want to get started, the P01-1AA2-01 (https://www.digikey.com/short/pw02p9m9) is in stock now for immediate delivery. Order today and you can get this part in your hands by tomorrow morning to help optimize your next Ethernet design!