Buck-boost charging IC supports dual-mode battery charge
4 January 2018 
The dual-input boost-buck charging ICs support one to four battery cells for notebook PCs, smartphones, and power banks. It is compatible with the latest charging technologies such as wireless and USB Power Delivery (USBPD), says Rohm Semiconductor.
The IC generates a charging voltage from 2.56 to 19.2V for up to four cells through boost-buck control. According to the company, the industry’s first dual-input charging system automatically switches charging operation without the need of a microcontroller using a built-in charging adapter function. Compatible with the USBPD and USB BC 1.2 standards, allows configuration of dual-mode systems capable of simultaneous charging via USBPD, or from an AC adapter.
Portable devices, including notebook PCs, are increasingly adopting the USB Type-C PD standard that can charge up to 100W, providing a common charging platform. At the same time wireless charging is gaining traction, increasing the demand to support both charging methods, says the company. However, in order to deliver a wide power supply range required by USBPD, a boost function must be added to the system to charge two-cell (~8.4V) batteries from conventional 5.0V chargers.
The BD99954GW and BD99954MWV ICs were developed by combining proprietary semiconductor technologies ing ICs that support both USBPD and 5V inputs in a single package.
A built-in charging adapter discrimination function enables automatic switching between modes without a microcontroller, eliminating the need to mount external peripheral components such as transistors and resistors for each charging system to reduce both mounting area and design load.
Step-up/down control makes it possible to generate the charging voltages necessary for USBPD operation (5.0 to 20V). For example, when charging a two-cell battery, boost-buck control enables step-down operation from 20 to 8.4V as well as step-up from 5.0 to 8.4V.
An evaluation board, the BD99954MWV-EVK-101 is also available.