A high-speed PWM controller that offers protection reduces power loss and meets IEEE802.3at standards simplifies the PoE design process.
Power Over Ethernet (PoE) is a transformative technology that enables Ethernet cables to carry electrical power alongside data, streamlining the deployment of networked devices. PoE simplifies installation, reduces costs, and minimizes cable clutter by eliminating the need for separate power and data connections. This innovation is crucial for modern networking, providing the flexibility to move quickly and scale devices and centralizing power management for improved control and reliability. PoE is pivotal in supporting the growing array of IoT and smart devices, enhancing safety with low voltage operation, and promoting energy efficiency through smart power allocation. ADM00844, PoE plus Powered Device (PD) reference design by Microchip simplifies the design process.
The MIC9130 is a current-mode PWM controller designed to convert –48V telecom voltages to logic levels efficiently. It features a high-voltage start-up circuit, allowing it to connect to input voltages up to 180V, thereby protecting the device from typical telecom system line transients. This start-up circuitry conserves board space and simplifies designs by integrating several external components.
The design is capable of high-speed operation and typically controls a sub-25ns pulse width on the gate output pin. Its internal oscillator operates over 2.5 MHz, with even higher frequencies available through synchronization. The device’s high-speed operation is safe due to its fast 34 ns response time from current sense to output, minimizing power dissipation during fault conditions.
The MIC9130 is designed for high-efficiency power supply designs, achieving efficiencies of over 90% at high-output currents. Its low quiescent current of 1.3 mA ensures high efficiency even at light loads. The design has a maximum duty cycle of 50% and operates within a rated junction temperature range of –40°C to +125°C. Additional features include a soft-start function, a resistor-programmable current sense threshold, selectable soft-start retry, and a robust output driver with a 4Ω sink and a 12Ω source.
The reference design offers a complete IEEE802.3at PoE Plus compliant power solution. The board features an integrated solution (NCP1093), a PoE signature and classification circuit, an EMI filter, and an isolated flyback DC/DC converter using the MIC9130 controller. When a powered Ethernet cable is connected to the board, the front-end handshaking circuit applies the correct signature and classification impedances to accept power from the PSE. Upon receiving power, with input voltages between 36V and 57V, the DC/DC flyback converter generates an 18.3V output with up to 1.7A of output current. This reference design is intended for use with IEEE802.3at PoE Plus enabled switch/routers that provide power to the Ethernet cable as defined by IEEE802.3at PoE Plus PSE requirements.
Microchip has tested this reference design. It comes with a bill of materials (BOM), schematics, assembly drawing, printed circuit board (PCB) layout, etc. You can find additional data about the reference design on the company’s website. To read more about this reference design, click here.
