Wireless charger modules optimise antenna layout for thin devices

Compact wireless charger modules with an integrated antenna board allow developers to add wireless power supply functionality to smaller devices such as smart tags/cards or PC peripherals. The BP3621 (transmitter) and the BP3622 (receiver) are available from Rohm Semiconductor.

Wireless power supplies are increasingly being adopted in smartphones, smart watches and other compact devices. One advantage is that using wireless power technology, means devices can improve water and dust resistance by eliminating the need for terminal contacts. The existing low frequency standards for power transmission, however, coupled with restrictive antenna designs can limit the degree of miniaturisation that can be achieved. As a result, demand is increasing for standards and methods that can be universally adopted in compact devices. 

Power transmission efficiency can vary depending on the antenna shape, size, and distance therefore it is often necessary to repeat prototyping, adjustment, and evaluation on the system. This can place a burden on the teams developing the antenna design and layout. In response, Rohm has developed 13.56MHz wireless charging modules that allow users to easily add wireless power functionality to thin and compact devices. Measuring just 20 to 30mm² each, the BP3621 (transmitter) and BP3622 (receiver) incorporate an optimised antenna (coil) layout. It enables configuration of a compact wireless charging system using the 13.56MHz frequency band to deliver up to 200mW. The back of the board is flat to facilitate its mounting in thin, compact devices and contributing to greater flexibility in chassis design. 

Using the transmitter and receiver modules as a pair can significantly reduce the development load for prototyping, adjustment, evaluation and other processes necessary to achieve high efficiency wireless charging. The integrated antenna supports bi-directional data communication and NFC Forum Type 3 Tag operation.

The BP3621 and BP3622 can be used in compact devices such as smart tags, smart cards and ID cards, mice, remote controls and other PC peripherals and in portable healthcare equipment.

Rohm has announced that it will develop further modules with efficient power transfer up to 1W and which are NFC Forum-compliant to support a wider range of applications.


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