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Use the Superior Power Density of Gallium Nitride FETs to Design a USB PD3.1 Power Supply with a 240 W, Universal AC Input

Use the Superior Power Density of Gallium Nitride FETs to Design a USB PD3.1 Power Supply with a 240 W, Universal AC Input

Aug 11, 2022

48 volts is increasingly being adopted as the new standard for computing data centers and consumer electronics such as laptops. The new USB PD3.1 standard is also making inroads into laptops driven in part by the increase in USB voltage to 48 V that increases the total power delivery up to 240 W given a current limit of 5 A for the connectors and cables. Compatible power supplies using the new USB PD standard also face increasing pressure to yield a small form factor solution driving the need for high power-density. The fast-switching speed and low RDSon of GaN FETs address this challenge in multiple circuits that make up the power supply.

The EPC9171 is a demonstration board designed to address all these design challenges and help jump start your project.  It features a low stage count approach for a universal AC voltage Input to 15 V through 48 V DC output with load current limit of 5 A suitable for USB PD3.1 power supplies.  The EPC9171 supports operation in Extended Power Range (EPR) Mode and achieves a power density of 1.1 W/cm3, operated at high switching frequencies, in both the primary and secondary circuits.

AC input power supplies require a PFC front end AC to DC converter to meet AC grid harmonic requirements, an isolation stage to meet safety requirements, and post regulator to meet load requirements. Each converter stage adds losses and increases the overall size of the converter. The design of the EPC9171 takes a unique approach to achieve high power density and high efficiency by employing an interleaving boost converter PFC stage followed by an isolated LCC resonant power stage as shown in Figure 1.

Figure 1: EPC9171 system block diagram.

Learn more by reviewing the quick start guide for the EPC9171 (/epc/Products/DemoBoards/EPC9171.aspx).  See the experimental validation of this design in our “How to” application note.