ROHM has unveiled a new wireless power supply IC chipset tailored for ultra-compact wearables and accessories, pairing the receiver ML7670 with the transmitter ML7671. The chipset leverages Near Field Communication (NFC) technology, making it ideal for smart rings, smart bands, and peripheral devices such as smart pens.
The smart ring segment has expanded quickly in recent years, driven largely by healthcare and fitness use cases.
For tiny ring-shaped devices worn on a finger, wired charging is simply impractical, while the standard Qi wireless charging system is hard to fit due to coil-size constraints. That’s creating strong demand for a compact, proximity-based power transfer method that can reliably charge these ultra-small devices.
In that context, NFC-based charging operating in the 13.56 MHz high-frequency band that supports much smaller antennas is gaining traction in next?generation wearables.
Building on the successful 1W ML7660/ML7661Â wireless power supply IC chipset, ROHM has developed the ML7670/ML7671 solution specifically for even more space-constrained form factors.
The new wireless power supply IC chipset inherits the proven architecture of the receiver ML7660 and transmitter ML7661, but is tuned for low-power applications. Maximum power transfer is rated at 250 mW, and the design integrates key peripheral components such as the switching MOSFETs needed to feed the charging IC.
This reduces external component count and streamlines the bill-of-materials, delivering a solution optimized for both mounting area and power-transfer efficiency at the 250 mW level typical for compact wearables, especially smart rings.
The ML7670 power receiver IC achieves a maximum power transfer efficiency of 45% in the 250 mW low?output range, all in an industry?leading package size of just 2.28 mm × 2.56 mm × 0.48 mm.
A standout feature of the chipset is its efficiency advantage over comparable solutions in the same class, gained by optimizing coil matching, rectifier circuitry, and switching losses across the path from coil to battery.
