While wireless charging continues to gain traction, a growing number of portable devices also are adopting the USB Type-C Power Delivery (USBPD) standard, which allows for charging up to 100 W (20 V/5 A). To deliver the wide power-supply range required by USBPD, a boost function must be added to a system to charge two-cell (approx. 8.4 V) batteries from conventional 5-V chargers. And if you want to enable the two different charging methods at the same time, it requires mounting charge ICs along with peripheral components as well as an MCU to control charge switching—all of which presents a barrier to introduction.
However, ROHM shows it can be done in a simpler manner. The company developed dual-input charging ICs supporting both USBPD and 5-V inputs in a single package that’s compatible with wireless as well as USBPD charging technologies. Support also is provided for USB Battery Charging Specification Revision 1.2 (USB BC 1.2), the key standard for establishing the proper way to charge a battery from a USB port (up to 7.5 W [5 V/1.5 A]). This facilitates configuration of dual-mode systems capable of simultaneous charging via USBPD or from an ac adapter.
1. ROHM’s dual-mode battery charger enables simultaneous USBPD and wireless charging.
The BD99954GW/MUV (Fig. 1) generates a charging voltage from 2.56 to 19.2 V for one to four cells (in series) through boost-buck control. A built-in charging adapter discrimination function enables automatic switching between modes without an MCU. This eliminates the need to mount external peripheral components, such as transistors and resistors, typically necessary for each charging system (for charge-path switching and backflow prevention), significantly reducing both mounting area and design complexity.
Packaging for the BD99953GW is a 0.4-mm pitch, 2.6- × 3.0- × 0.62-mm wafer-level CSP designed for space-constrained equipment such as low-profile notebook PCs, tablets. and other applications. The BD99954MWV comes in a 0.4-mm pitch, 5.0- × 5.0- × 1.0-mm QFN package. The parts provide a dual-source battery charger, two-port BC1.2 detection, and a battery monitor with several alarm outputs.
Step-up/down control makes it possible to generate the charging voltages necessary for USBPD operation (5 to 20 V). For example, when charging a two-cell battery (approx. 8.4 V), boost-buck control enables step-down operation from 20 V to 8.4 V as well as step-up from 5 V to 8.4 V. Samples of the ICs are currently available; OEM quantities will be available as of January 2018.
To assist engineers, ROHM has introduced an evaluation kit for the BD99954 battery-management system. Designated BD99954MWV-EVK-101 and featuring a GUI, users can access the battery-charging profile and modify and read back the registers of the device (Fig. 2).
2. The BD99954MWV EVK acts as a platform for the BD99954 battery-management LSI. With the included software GUI, users can access the battery-charging profile and modify and read back the registers of the BD99954.
The BD99954MWV EVK-101 board comes with a bill of materials, schematics, board layout, and application data. It features a reverse buck/boost option and an on-board USB-to-I2C communication circuit. Its input operating range is 3.8 to 25 V. In addition, a user manual for the I2C control software is included to help program the BD99954MWV.
Operation is straightforward: Make sure the BD99954 board is connected to your PC via a USB cable and is powered on with a power supply. Once connected, click on the BD99954 I2C Control icon located on the desktop GUI, or find the application in the Windows Start Menu to start the program. Upon starting the program and the BD99954 board being powered up with the appropriate voltage, the software will indicate in the top-right corner if the board is properly connected.