April 28, 2026 /SemiMedia/ — ROHM has launched a new NFC-based wireless power chipset designed for compact wearable devices such as smart rings and smart bands.

The chipset includes the ML7670 receiver and ML7671 transmitter, supporting wireless power transfer up to 250mW. It operates in the 13.56 MHz NFC band, which allows smaller antenna design compared with conventional wireless charging methods.

Very small devices like smart rings face limits with wired charging, while standard Qi solutions are hard to use due to coil size and layout constraints. NFC-based power transfer offers a simpler option for these use cases.

The ML7670 achieves up to 45% efficiency in the 250mW range and comes in a compact package of 2.28 × 2.56 × 0.48mm. The chipset also integrates key external components, including switching MOSFETs, helping reduce the number of parts and PCB area.

ROHM said the design improves efficiency by tuning coil matching, rectifier circuits, and switching performance. Firmware for wireless power control is built into the IC, so no external MCU is required, which helps simplify system design.

The chipset supports NFC Forum WLC 2.0, allowing compatibility with existing NFC systems. It is already in mass production. For more information, please visit ML7670 and ML7671.