Contactless wireless charging solution packages power transmitter, receiver ICs for healthcare and wearable applications

SANTA CLARA, CA. Renesas Electronics has announced the RAA457100 power receiver and RAA458100 power transmitter integrated circuits (ICs) a contactless wireless charging solution for low-power wearable applications that require resistance to water and dust. Each IC includes all functions needed for wireless charging on a single chip, and an evaluation kit is also being developed for manufacturers of wireless charging designs.

The 3.22 mm x 2.77 mm RAA457100 power receiver incorporates a synchronous rectifier circuit that recycles AC power used to excite the receiver’s antenna coil into direct current, as well as a charging control circuit used to charge a secondary lithium-ion (Li-Ion) battery. A 12-bit analog-to-digital converter (ADC) is included in the RAA457100 monitors battery voltage and current during charging, data that is provided to the power transmitter in order to maintain optimal charging power levels. Along with Li-Ion battery protection measures, when operating at 1 mA loads an included DC/DC converter is capable of operating at 85 percent efficiency.

A 125 kHz alternating current is applied to the RAA458100 power transmitter IC’s antenna coil which is then used to excite the power receiver’s antenna coil for contactless AC power transmission. The RAA458100 drives a bridge circuit and controls alternating current in order to obtain power values required by the power receiver, and developers can alternatively modify these parameter values by programming read registers with external EEPROM data via an I2C interface or customize the solution by configuring the bridge circuit using power MOSFETs such as the μPA2690T1R. An external MCU can also be used to customize the RAA458100. In addition, the power transmitter IC includes bridge circuit overcurrent protection and two-line external overheating protection.

Samples of the new wireless charging system solution will be available in November 2016.  For more information about Renesas’ wireless charging solution, visit