EDOM technology: new 13.56 MHz wireless power chipset from ROHM up to 1W

Provide wireless charging and communication functions with a single chipset

The ROHM LAPIS Technology group company has developed a chipset capable of delivering up to 1W of wireless power for compact and streamlined portable devices, and for a smart, miniaturized and sealed industrial solution. The ML7661 (transmitter) and ML7660 (receiver) eliminate the need for an external MCU by incorporating a control circuit required for transmit / receive, resulting in the industry’s smallest system size in the 1W class. This makes it ideal for portable devices with a large battery capacity designed to be worn for long periods of time. Typical products are wrist blood pressure monitors, fitness trackers, smart watches and hearing aids, for example. In addition, the adoption of the high frequency band of 13.56 MHz enables the support of near field communication (NFC).

Providing power and wireless communication in a single chipset contributes to greater design flexibility for devices with rotational mechanisms that would normally be limited by hard-wired designs, such as industrial equipment, cooling fans for PC and torque sensors for electric bikes.

In recent years, there has been a growing need to improve the safety of compact electronic devices (especially small medical devices) against electric shock. Wireless power eliminates the need for a power cord, dramatically improving safety while charging or sweating by increasing the waterproof performance, dust protection and (electric) shock of sealed cases. However, although the Qi standard is widely used and can deliver up to 15W, the size of the system which includes the chipset and antenna is also generally large, making it difficult to integrate into portable devices.

In response, the ROHM Group company LAPIS Technology previously developed the ML763x chipset which uses the 13.56 MHz frequency band to deliver 200 mW of power and enable wireless communication. But while it has been well received by the market, there have been calls for increased power to support portable devices with large battery capacities such as wrist blood pressure monitors, smart watches, and hearing aids. ROHM’s latest chipset addresses this need by delivering power capacity of up to 1W in a compact form factor, expanding the range of applications.

Main characteristics
1. Delivers up to 1W of power in the industry’s smallest system size ROHM’s new chipset enables wireless power up to 1W by optimizing the control of power transmission according to the amount of power required while removing heat generation from the integrated circuit itself. In addition, the adoption of the high frequency band of 13.56 MHz for power supply can reduce the size of the antenna, thereby reducing the size of the system by 30% compared to standard products – ideal for compact devices such as blood pressure monitors, smart watches and hearing aids. In addition, a built-in communication protocol supports I2C and SPI interfaces, allowing control of digital sensors and other devices without MCUs. Eliminating the required MCU mounting area results in the industry’s smallest system size (even compared to general class 1W power supplies).

2. Enabling both wireless power and communication contributes to greater flexibility in application design.
ROHM’s new chipset uses the 13.56 MHz frequency band for wireless power as well as near field communication (NFC). Providing contactless power and communication with a single chipset contributes to greater design flexibility for devices with rotational mechanisms that would be limited by hard-wired designs, such as industrial equipment, cooling fans for PC and torque sensors for electric bikes. In addition, adopting a single communication format reduces the communication interval from 4 ms with the ML763x to just 1 ms in the ML766x, which allows for improved control and monitoring of rotational speed. real time.

3. System configuration without MCU reduces development load
ROHM’s new chipset makes system setup easier by adjusting power transmission to increase power efficiency and setting parameters such as temperature thresholds based on rechargeable battery specifications. This eliminates the need for a system control MCU as well as the required program development, greatly reducing the development load. At the same time, a low power consumption mode is included which significantly reduces power consumption during system standby.

Development support
An evaluation kit is available which allows the evaluation of this new 13.56 MHz wireless power chipset to begin immediately. ROHM supports the configuration of charging systems that meet various customer requirements. For example, tools for individual user settings from a PC as well as documents related to antenna design and tuning are available. Click on the URL below for more information:
https://www.lapis-tech.com/en/semicon/wpt/landing/ml7660_61.html

Product specification

Applications

• Portable medical devices up to class 2: hearing aids, wrist blood pressure monitors

• Wearable devices: glasses / smart watches

• Rotating equipment: cooling fans, torque sensors for electric bikes

Availablity: September 2021 (samples), April 2022 (mass production)

Terminology
Near Field Communication (NFC)
A short range wireless communication technology that uses the 13.56 MHz band. Specifications are set by the NFC Forum, an industry standards body. ROHM is an associate member of the NFC Forum.

Qi standard
An international standard for wireless power transfer developed by the Wireless Power Consortium. Often adopted for wireless charging of smartphones.

I2C / SPI interfaces
I2C, short for Inter-Integrated Circuit, and SPI, short for Serial Peripheral Interface, are synchronous serial communication methods used to connect devices inside a computer. Unlike asynchronous serial communication, they can connect multiple slaves and transmit at high speed.

Torque transducer
A sensor that converts the magnitude of force (torque) during rotation into electrical signals. On an electric bicycle, it is used to sense the amount of pedal depressed and send it back to the motor.

Source: ROHM website