In Ethernet interface design, the magnetics module is often treated as a given — yet it directly determines whether a link passes IEEE 802.3 compliance, whether it can carry PoE current, and whether the design clears EMC testing on the first attempt. Pulse Electronics is one of the major global suppliers of network magnetics. This article examines the company background, the device working principles and the product families, covering the 50 most-quoted part numbers this week.
Pulse Electronics was founded in 1956 in Redwood City, California, with more than sixty years of magnetics design and manufacturing experience, and was acquired by YAGEO in 2018. Its portfolio covers LAN magnetics, power magnetics, current sensing, antennas, connectors and cable assemblies, serving communications, computing, consumer, industrial and automotive customers.
Two blocks are directly relevant to the part numbers discussed here: network magnetics, comprising discrete LAN transformer modules and the PulseJack series of RJ45 integrated magnetics connectors (ICM); and signal/current-sense transformers, used for isolated drive, telecom interfaces and current sampling.
In a 10/100/1000Base-T interface, the magnetics module performs the following work — and these are the dimensions that actually matter during selection:
Open-circuit inductance (OCL, typically specified as a minimum at 8 mA bias, e.g. 350 µH) is the commonly used indicator of whether a part meets IEEE 802.3 link requirements.
H1102NL, H1102NLT, H1102FNLT, H1012NL, H1012NLT, HX1188NL, HX1188NLT, HX1188FNLT, H1164NL, H1164NLT.
This family is the workhorse of Fast Ethernet interfaces: single port, surface mount, compact package, compliant with IEEE 802.3, with a 245 °C peak reflow rating. The H1102 series offers multiple turns-ratio options to match different PHY solutions; the H1012 series are 1:1 transmit-ratio transformer modules documented as compatible with Broadcom, Intel, Microtel, National Semiconductor, ICS and TDK transceivers; the HX1188 series are 100Base-TX single-port SMT magnetics with 1:1 turns ratio and 1500 V isolation class, where the F suffix corresponds to a specific package/height and PoE configuration — substitutes must be verified item by item against the datasheet.
H5007NL, H5007NLT, H5008NL, H5008NLT, HX5008NL, HX5008NLT, H5004NL, HX5004NL, HX5004NLT, HX5084NL, HX5084NLT, HX5020NL, H5020NL, H5084NL, H5120NL, H5120NLT, HX5120NL, HX5120NLT.
Gigabit parts are structurally more complex — typically a 12-core architecture with 1CT:1CT turns ratio — to keep impedance consistency and return loss acceptable while all four pairs operate simultaneously. Taking HX5008NL as an example: the official product data lists 1000Base-T speed, 4-pair PoE 30 W support and an operating range of −40 °C to +85 °C, an industrial-grade configuration. H5004NL, H5007NL and HX5004NL are footprint-compatible with the 10/100Base-TX part H1267, allowing the same PCB to be upgraded to gigabit or downgraded to Fast Ethernet in a platform design — a practically useful property for hardware engineers. H5008NL is a 1:1 single-port gigabit module that likewise covers the industrial temperature range.
HX1234NL, HX1234NLT, H2019NL, H2019NLT, HX2019NL, HX2019NLT, HX6096NL, HX0068ANLT, H0013NL.
These parts cover multi-port variants, different speed grades and specific application configurations (automotive grade, wide temperature or special packages), along with derivatives matched to particular platforms. Selection should rely on the official product page's SPEED, port count, PoE rating and temperature range — the speed should not be inferred from the model number alone.
J0011D21BNL, J0011D01BNL, J00-0045NL, J00-0065NL, J1011F01PNL, J3011G21DNL.
PulseJack integrates the RJ45 jack, transformer, common-mode choke and LEDs into a single connector (ICM). Taking the J0 series as an example: 100Base-TX, 1×1 Tab-Down, 8-pin, with LEDs, compliant with IEEE 802.3, minimum OCL of 350 µH at 8 mA bias, suited to SOHO (ADSL modems), LAN-on-Motherboard (LOM), hubs and switches — it reduces board space and trace length compared with discrete magnetics. The J1/J3 series differ in latch orientation, port count and speed configuration for multi-port equipment or different panel designs.
PA1005.100NLT.
The PA1005 series are low-profile EE5 surface-mount current-sense transformers, approximately 5.5 mm tall, operating from 50 kHz to 1 MHz. This part has a 1:100 turns ratio, a 20 A current rating, 2 mH secondary inductance, roughly 0.75 mΩ primary resistance and 5.5 Ω secondary resistance, using an invasive (single-turn primary through the core) construction. It is used for primary-side current sensing in switching supplies, motor drives and inverters, converting high current into a measurable secondary signal at the defined ratio while providing isolation. The series also includes AEC-Q200 automotive-grade versions (QNL suffix) for automotive and industrial use.
PA0184NLT, P0353NLT, P0420NLT, P0502NLT, PE-65612NL, PE-68386NLT.
This group comprises general-purpose signal transformers for telecom interfaces, isolated drive and audio/signal coupling. Taking PE-68386NLT as an example: 1:1 turns ratio, 785 µH inductance and 9.7 Vµs volt-time product — a low-power signal isolation part. The PA/P/PE prefixes correspond to different historical product lines and package systems, so turns ratio, inductance, ET value and isolation withstand voltage must all be checked during selection.
Based on the families above, the following should be verified in order:
Pulse's portfolio is essentially a magnetics matrix built around the Ethernet physical layer: from 100Base-T single-port transformers and gigabit 12-core modules, to the PulseJack ICM that combines RJ45 and magnetics in one part, and on to current-sense and signal isolation transformers. Understanding turns ratio, OCL, the PoE path and isolation class matters more than memorizing part numbers — a part number is merely the combination of these parameters under a specific package and temperature grade.
