According to Semiconductor Today, Efficient Power Conversion Corp has launched the EPC91120, a 3-phase brushless DC motor drive inverter specifically optimized for humanoid robot joints and UAVs. The board integrates three EPC23102 GaN half-bridge ICs and operates from 15V to 55V DC, delivering up to 21A peak current and 15A continuous. It features a compact 32mm-diameter footprint designed to fit directly into robotic motor assemblies like the Unitree A1 robot. The system achieves over 80% efficiency from DC input to mechanical output and can deliver 7A per phase without a heatsink. The EPC91120 reference design boards are priced at $394.02, while the EPC23102 ICs cost $4.80 each in volume, with both available immediately through Digi-Key.
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Why this matters
Here’s the thing about robotics – power electronics have always been the bulky, inefficient part that designers had to work around. You’d have these sleek robot designs, then clunky external motor controllers spoiling the aesthetic and adding weight. EPC’s approach basically flips that script by putting the power electronics right inside the joint itself. That 32mm diameter? That’s tiny. And getting 80%+ efficiency in that package is genuinely impressive when you consider traditional silicon-based solutions would be larger and run hotter.
GaN vs silicon
This is where gallium nitride really shows its advantages. The EPC91120 operates at 100kHz PWM switching frequency with only 50ns dead time – numbers that silicon-based solutions would struggle to match without serious thermal consequences. GaN devices can switch faster and run cooler, which is exactly what you need when you’re cramming power electronics into tight spaces. Think about it – if you’re building a humanoid robot, every watt of power you save on motor drives means either longer battery life or more computing power for AI tasks. It’s not just about making robots more efficient – it’s about enabling capabilities that simply weren’t practical before.
Market implications
At $394.02 for the evaluation board, this isn’t exactly hobbyist territory, but for robotics companies developing production systems, that’s actually quite reasonable for a reference design of this sophistication. The real story is the $4.80 per IC in volume – that puts GaN technology squarely in the realm of mass production for robotics. We’re likely seeing the beginning of a shift where GaN becomes the default choice for high-performance motor drives, leaving silicon solutions for less demanding applications. Companies still relying on older power technologies might find themselves at a serious disadvantage when competing on robot weight, efficiency, and responsiveness.
The fact that EPC designed this specifically for the Unitree A1 robot motor tells you everything about their target market. They’re not just selling components – they’re selling complete solutions for the companies actually building the next generation of robots. And with EPC’s broader GaN portfolio, they’re positioning themselves as the go-to power electronics provider for an industry that’s about to explode.
