All new electronic devices are now coming with the USB-C interface, and this is revolutionizing the way people charge the devices. So far, most electronic devices had the micro-USB type-B connectors. With the USB Type-C connector, it is immaterial what orientation you use for the charging cable—the non-polarized connector goes in either the right side up or upside down. The connecting system is smart enough to figure out the polarity as a part of the negotiation process, and supports bidirectional power flow at a much higher level.
Earlier, the USB connectors handled only the 5 VDC fed into them. The USB-C port can take in the default 5 V, and depending on the plugged in device, raise the port voltage up to 20 V, or any mutually agreed on voltage, and a preconfigured current level. The maximum power delivery you can expect from a USB-C port is 20 V at 5 A or 100 W. This is more than adequate for charging a laptop. No wonder, electronic device manufacturers are opting for incorporating the USB-C into their next-generation products.
With the increasing power delivery through the USB Type-C ports, the computer industry has had to raise the performance requirement of the voltage regulator. Unlike the USB Type-B and the USB Type-A fixed voltage ports, the USB Type-C is a bidirectional port with a variable input, and an output range of 5-20 VDC. This adjustable output voltage feature allows manufacturers of notebooks and other mobile devices to use USB Type-C ports to replace the conventional AC/DC power adapters and USB Type-B and A terminals. Manufacturers are taking advantage of these features and incorporating dual or multiple USB Type-C ports into their devices.
However, using the current system architecture for implementing dual or multiple USB Type-C ports, leads to a complicated situation. It is unable to meet many requirements of the customers. As a solution, Intersil has proposed a new system architecture using the ISL95338 buck-boost type of regulator, and the ISL95521A, which is a combo battery charger. Use of these devices simplifies the design of the USB-C functions and fully supports all features. Applied on the adapter side, manufacturers can implement a programmable power supply, and it offers an adjustable output voltage that matches the USB-C variable input voltage.
In the proposed design, Intersil offers an architecture with two or more ISL95338 devices in parallel. Each of them interfaces a USB Type-C port to the ISL95521A battery charger. As this architecture eliminates several components from the conventional charging circuit, including individual PD controllers, ASGATE and OTG GATEs, it saves manufacturers significant costs. For charging a battery, power is drawn directly from the USB-C input to the ISL95521A, and the multiple ISL95338s offer additional options.
For instance, the user can apply two or more USB-C inputs with different power ratings for charging the battery fast. Therefore, the battery charge power is now higher than that supplied by a single USB-C input power. It also means there is no need for adding external circuitry to determine the different power rating operations of the paralleled ISL95338 voltage regulators.