Unlock Compact Power: Ultra-Compact, High-Efficiency 180 W GaN Buck Converter Evaluation Board for USB PD Applications
GaN Talk – Parinda Chantarasereekul
Jun 26, 2025
In the race for higher power density and efficiency, the EPC91109 evaluation board was designed to showcase the full capabilities of gallium nitride (GaN) FETs in USB Power Delivery (USB-PD) and other compact applications.
Compact Power Design for USB PD Applications
The EPC91109 is a two-phase synchronous buck converter reference design optimized for step-down conversion from 20 V to 36 V inputs to regulated outputs of 12 V, 16 V, or 20 V, common battery voltage for USB applications. This flexibility, combined with a tiny 24 x 24 mm power stage, makes it ideal for laptops and other USB PD-based applications up to 180 W.
Inside the EPC91109: GaN FETs + Dual-Phase Buck Controller
At the heart of the EPC91109 are four EPC2057 50 V GaN FETs, offering low RDS(on) of 8.5 mΩ and fast switching speeds in a tiny 1.5 x 1.2 mm size. These are driven by the Analog Devices LTC7890 dual-phase buck controller, enabling nearly zero dead-time switching. This combination of fast switching speed and minimal deadtime results in high efficiency and high power density, even without the need for a heatsink or forced airflow.
Figure 1: EPC91109 Power Circuit
Performance Highlights: 180 W Output with >98% Efficiency
Despite its compact size, the EPC91109 delivers impressive performance, supplying up to 14.3 A into a 12 V load from a 36 V bus. Thus, covering up to 180 W of power delivery over a USD cable according to the USB PD 3.1 specification. The converter operating at a switching frequency of 970 kHz, achieving peak efficiency and full load efficiency exceeding 98%—all without the need for a heatsink or forced-air cooling.
Figure 2: Measured efficiency of the EPC91109 board for multiple input voltages and VOUT = 16 V, without airflow and without a heatsink installed.
Measured Results: Efficiency, Ripple, and Transient Response
The EPC91109 has been thoroughly validated under real-world operating conditions to demonstrate its reliability and performance. In a typical test scenario—36 V input, 12 V output, and a 14.3 A load—the board delivered consistent, high-efficiency power conversion while maintaining thermal stability without the aid of a heatsink or forced-air cooling.
Thermal imaging confirmed that even at maximum rated current, the board stayed within safe temperature limits, reaching thermal steady-state without external airflow. Voltage regulation was tightly controlled across a range of load currents and input voltages, with minimal variation.
Figure 3: Steady state measured thermal image of the EPC91109 operating with 36 V input, 12 V output and delivering 14.3 A into the load, without airflow or a heatsink.
In addition, the transient response was robust and well-damped: during a load step change from 10% to 90% (and back) of full load, the output ripple remained below 50 mV peak-to-peak.
Figure 4: Measured transient waveform of the EPC91109 operating with 36 V input, 12 V output and with a load step change of 10% to 90% and 90% to 10% of 14 A.
These measurements—taken directly at the power outputs and switch nodes—demonstrate that the EPC91109 not only meets performance expectations but does so with the simplicity and thermal efficiency made possible by GaN technology.
Configure the EPC91109 for Application-Specific Testing
The EPC91109 evaluation board offers a high degree of configurability through its intuitive jumper settings, allowing engineers to easily tailor operation to their specific application needs. Users can select between three common output voltages—12 V, 16 V, or 20 V—using a single jumper on the output selector header, making the board suitable for a variety of USB Power Delivery scenarios.
For greater design flexibility, the board can be configured either as a dual-output buck converter or as a two-phase interleaved converter with a single output, enabling improved current sharing and reduced ripple. Additionally, engineers can fine-tune switching performance by selecting between three preset dead-time settings (near-zero, ~5 ns, or 20 ns) to balance efficiency and safe switching behavior.
Light-load operation is also adjustable via jumper, with support for Burst Mode®, Skip Mode, and continuous conduction mode (CCM), giving designers the ability to optimize power consumption and noise characteristics under low-load conditions.
These features make the EPC91109 a versatile and engineer-friendly platform for evaluating high-performance GaN-based power conversion.
Figure 5: EPC91109 selector point locations and designations for mode settings
Ready to Power Up?
If you're developing next-generation portable power systems, the EPC91109 gives you a hands-on preview of how GaN can unlock performance that silicon simply can’t match.
Explore the full specifications and technical documentation for the EPC91109 on the product page.
Have questions or need help with system integration? Contact EPC’s applications team to discuss your design requirements.
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