Single-chip USB-C buck-boost battery charger

November 11, 2016 // By Graham Prophet
Intersil's ISL9238 and ISL9238A add 5V-20V reverse boost for USB On-The-Go charging of portables such as smartphones and headphones; two USB-C buck-boost battery chargers support bidirectional power delivery in ultrabooks, tablets, power banks and other mobile products.

The single-chip ISL9238 and ISL9238A battery chargers can replace two-chip solutions to reduce bill of materials (BOM) costs by up to 40%. Both ICs employ Intersil’s R3 modulation technology to extend battery life and deliver acoustic noise-free operation, improved light-load efficiency and fast transient response. The ISL9238 and ISL9238A operate in forward buck, boost or buck-boost mode to fast charge mobile battery packs with up to 4-cell Li-ion batteries. They also support USB 3.1 On-The-Go (OTG) with 5V/20V reverse buck, boost or buck-boost mode to deliver power out of a USB-C port for charging external devices such as smartphones, headphones or virtual reality goggles. At maximum power, both ICs provide 20V at 5A to the USB-C port for delivery of power up to 100W over a reversible USB Type-C connector cable.


The ISL9238A features the same capabilities as the ISL9238, but also includes a different SMBus address for OEMs that want to use both ICs to design systems with dual USB-C ports. In charging mode, the ISL9238 and ISL9238A take input power from a wide range of DC power sources, including AC/DC charger adapters, USB power delivery (PD) ports and any travel adapter. Both chargers include SMBus and I ²C programmable features such as depleted battery trickle charging, and a two-level adapter current limit for turbo-mode events where the charger takes advantage of the adapter’s milliseconds of surge current capability to minimize power draw and extend battery run-time. The ISL9238 and ISL9238A also feature programmable autonomous charging and an end of charge safety timer to stop battery charging.


Features include;

- Buck-boost NVDC charger for 1-, 2-, 3-, or 4-cell Li-ion batteries

- Input voltage range of 3.2V to 23.4V (no dead-zone)

- System output voltage of 2.4V to 18.304V

- Up to 1 MHz operation allows use of smaller, lower cost inductors and automatically reduces switching frequency with no audible acoustic noise when charger is in