| Title of Reference Design | Power Over Ethernet | PoE for Industrial Gateways | A Power Supply in a PoE | PoE Plus Power Design | PoE Flyback Power Supply |
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| Key Attractions | The design features a 3.3V/20A DC-DC active clamp forward converter with a power over Ethernet interface and dual active bridges. It is suitable for versatile applications, offering operational flexibility and compact integration. | The reference design integrates PoE technology with an Ethernet microcontroller, enabling IoT application development. It supports power extraction from network cabling and facilitates data processing and cloud communication. | The evaluation board serves as a reference design for PoE applications, offering a 12V/6A output with 91% efficiency. It features integrated protection systems and supports up to 1000Mbps speed, optimising space and power management across conditions. | The design integrates power conversion and protection for telecom applications, supporting high-speed operations and synchronisation capabilities. It offers power management, achieving efficiency and output. | The PoE module reference design delivers 5V at 12.5W from a 36V to 57V input, featuring a no-opto isolated flyback converter with 85% efficiency. Suitable for various stages of development, it offers control and power management capabilities. |
| Highlights | The reference design from STMicroelectronics, which features a 3.3V/20A DC-DC active clamp forward converter, streamlines the design process for a variety of applications, including wireless access points, and is further enhanced by a power over Ethernet (PoE) PD interface. This design integrates the PM8805 system, which includes two active bridges and an IEEE 802.3bt-compliant powered device (PD) interface, suited for medium-to-high power applications across both 2-pair and 4-pair high-efficiency PoE and PoE+ systems. Equipped with 100V N-channel MOSFETs, the PM8805 offers a low total path resistance of 0.2Ω for each bridge and features capabilities to identify the type of power sourcing equipment (PSE) and provide clear IEEE 802.3af/at/bt classification indications. Additionally, the system offers operational flexibility with smart mode selection, allowing for tailored device functionality, and is packaged in a compact QFN 56 8mm×8mm format for easy integration. | The reference design TIDM-1018 by Texas Instruments integrates its power over Ethernet (PoE) technology with the SimpleLink MSP432E4 Ethernet microcontroller (MCU), enabling the development of Internet of Things (IoT) applications on a compact board. The design allows power to be drawn from existing network cabling while enabling data processing and cloud communication. It includes an RJ45 connector, transformer, and a PoE power stage diode bridge. The board also features a 7W isolated output from a fly-back converter, providing 5V and 3.3V output power rails and an optional power header for external DC power supply in case of network power failure. The board includes dual BoosterPack plug-in module headers compatible with various booster packs for rapid prototyping. The MSP432E401Y MCU operates at 120MHz with 1MB flash and 256kB SRAM, includes cryptographic modules for secure data operations, and additional components. | The Si34071 isolated forward topology evaluation board by Skyworks serves as a reference design for a power over Ethernet (PoE) powered device (PD) application, featuring the Si34071-FW-12V-C8 model that delivers a 12V/6A isolated output. It achieves 91% efficiency and meets IEEE 802.3bt and EMI standards, and includes features such as Autoclass, integrated transient overvoltage protection, and thermal shutdown protection. The compact 5mm x 5mm 32-pin QFN package optimises space. The DC/DC converter on the board features reset winding forward mode for low-power scenarios and active clamp forward mode for high-power requirements, ensuring efficient power management across conditions. Although the board does not support Ethernet data transmission, it connects secondary-side data from the Ethernet transformer to another connector, supporting speeds up to 1000Mbps through the PoE+Data RJ45 connector. | The ADM00844, a PoE plus powered device (PD) reference design by Microchip, simplifies the design process with elements for power conversion and protection for telecom applications. The design supports high-speed operation, controlling a sub-25ns pulse width on the gate output pin, operates with an internal oscillator over 2.5MHz, and achieves higher frequencies through synchronisation. It also minimises power dissipation during fault conditions with a fast 34ns response time from current sense to output and maintains efficiencies over 90% at high-output currents with a low quiescent current of 1.3mA. The design includes a soft-start function, a resistor-programmable current sense threshold, selectable soft-start retry, and a robust output driver. It performs front-end handshaking to accept power from the PSE when a powered Ethernet cable is connected, generating an 18.3V output with up to 1.7A of output current from input voltages between 36V and 57V. | The MAXREFDES128 PoE module reference design from Analog Devices outputs 5V at 2.5A (12.5W) from an input range of 36V to 57V, suitable for evaluation, design, prototyping, and production. It includes control circuitry and electrical components necessary for constructing an isolated flyback converter power supply. The module comprises two sections: the PD controller and the no-opto flyback DC-DC converter. The no-opto flyback DC-DC converter uses a 60V peak current mode, fixed-frequency switching controller designed for discontinuous conduction mode (DCM) and achieves 85% efficiency at a 100kHz switching frequency. It includes a primary-side MOSFET for energy storage in the transformer’s winding and a secondary-side synchronous MOSFET driver for efficiency and thermal management. The design also features startup and input overvoltage protection settings with a 5ms soft start to reduce PSE inrush current, utilises a resistive divider for setting switching thresholds, and includes two 6-pin connectors and two bridge rectifiers for compatibility with various PSE types. |
| Applications | The reference design is suitable for compact, high-efficiency applications. | The design is suitable for HVAC gateways, HVAC system controllers, security gateways, and condition monitoring gateways. | The reference design is suitable for a power supply within a PoE powered device (PD) application. | The reference design is suitable for telecommunications, networking, security systems, wireless access, and industrial automation. | The reference design is suitable for stable power delivery across various applications. |
| OEM Brand | STMicroelectronics | Texas Instruments (TI) | Skyworks | Microchip | Analog Devices (ADI) |
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Nidhi Agarwal is a journalist at EFY. She is an Electronics and Communication Engineer with over five years of academic experience. Her expertise lies in working with development boards and IoT cloud. She enjoys writing as it enables her to share her knowledge and insights related to electronics with like-minded techies.
