ROHM Launches NFC Wireless Power Chipset for Compact Wearables

Why It Matters

By enabling efficient, low‑power wireless charging in a sub‑3 mm package, ROHM removes a key barrier to truly miniature wearables, accelerating product innovation and market adoption.

Key Takeaways

• ML7670/ML7671 deliver up to 250 mW wireless power.
• Chipset achieves 45 % efficiency at 250 mW output.
• Package size 2.28 × 2.56 × 0.48 mm fits tiny wearables.
• Integrated MOSFETs reduce parts and PCB area.
• Supports NFC Forum WLC 2.0, compatible with existing NFC devices.

Pulse Analysis

The wearable market has been constrained by the physical limits of traditional Qi charging, which requires relatively large coils that simply cannot fit on devices the size of a ring or a thin band. Consumers demand seamless, on‑the‑go power, yet wired solutions are impractical for such form factors. NFC‑based power transfer, operating at 13.56 MHz, offers a compelling alternative because its antenna can be dramatically smaller while still delivering usable power levels for low‑energy sensors and displays.

ROHM’s ML7670/ML7671 chipset tackles these challenges head‑on. The receiver and transmitter are packaged in a 2.28 × 2.56 × 0.48 mm footprint, integrating the necessary switching MOSFETs and rectifier circuitry. This integration eliminates the need for external components and an additional microcontroller, simplifying board layout and reducing bill of materials. With up to 45 % efficiency at a 250 mW transfer rate, the solution provides sufficient power for continuous operation of smart rings, health‑monitoring bands, and other ultra‑compact devices without sacrificing battery life.

The broader impact extends beyond individual products. By adhering to NFC Forum WLC 2.0 standards, the chipset can leverage the existing NFC ecosystem, allowing manufacturers to reuse NFC readers already embedded in smartphones and payment terminals for charging purposes. This compatibility lowers entry barriers for startups and accelerates time‑to‑market for innovative wearables. As designers adopt the ML7670/ML7671, we can expect a new wave of truly miniature, always‑on accessories that blend seamlessly into daily life, reshaping consumer expectations for convenience and functionality.