Wireless-Power Chipset Targets Small Wearables

A wireless power-supply IC chipset developed by ROHM is compatible with near-field communication (NFC) technology for compact wearables such as smart rings, as well as peripheral devices like smart pens. Consisting of the ML7670 receiver and ML7671 transmitter, the chipset targets small devices where wired charging is impractical, and the conventional Qi wireless-charging standard is difficult to implement due to constraints such as coil size.

By using NFC-based charging, which operates at the high-frequency 13.56-MHz band that enables antenna miniaturization, the ML7670/ML7671 chipset is optimized for even smaller devices. Features include a maximum power transfer of 250 mW, with peripheral components like the switching MOSFETs required to supply power to the charging IC being built in.

Optimized for both mounting area and power transfer efficiency, the 2.28- × 2.56- × 0.48-mm ML7670 power receiver IC achieves a maximum power transfer efficiency of 45% in the 250-mW low output range, with optimized elements such as coil matching, rectifier circuitry, and reduced losses in switching devices.

All firmware required for wireless power delivery is embedded directly within the IC, eliminating the need for a host MCU. Compliance with the NFC Forum (WLC 2.0) enables power transfer while maintaining compatibility with existing devices, and evaluation boards and reference designs are offered to facilitate integration. 

Related links:

• ROHM
• ML7671 Transmitter
• ML7670 Receiver
• More New Products