■ USB-C boasts excellent flexibility

USB-C is becoming a standard in a variety of consumer devices. USB-C offers much greater flexibility than previous USB ports. Consumer devices are increasingly demanding higher power and longer battery life.

Therefore, the need to charge these devices at higher power is also increasing. This article introduces parallel battery charging architecture and use cases, and explains how to utilize USB-C in these use cases.

We also explore the pros and cons of parallel battery charging and USB-C in the consumer market.

■ What is parallel battery charging?

In a battery management system (BMS), the battery configuration can be different depending on each need. If the batteries are arranged in a series configuration, the battery capacity can be the same but a higher voltage can be achieved.

This configuration is mainly used in high power products. Another way is to configure the batteries in parallel.

This configuration can provide higher capacity at the same voltage. With today's consumer devices demanding long battery life, manufacturers need to be creative in extending battery life while conserving the usable capacity of the battery pack.

A simple yet effective way to extend battery life is to use parallel charging. Simply put, parallel charging batteries allows users to charge multiple batteries at the same time, which increases battery life and reliability. Figure 1 shows the basic series and parallel battery configurations that are commonly used.


■ Parallel battery charging using USB-C

As mentioned earlier, USB-C ports and devices can charge at higher power levels than their predecessors USB 2.0 and USB 3.0.

The latest USB-C specification, Power Delivery 3.1, can provide up to 240W. While that may be overkill for most consumer products, it shows that USB-C is more robust than previous USB generations.

In addition to delivering this much power through USB-C ports, consumers are increasingly demanding more power and longer battery life.

A parallel battery configuration can meet these needs. As the battery capacity of consumer devices increases with parallel battery configurations, the power requirements of the charger that supplies power to the devices also increase.

Another important need in the consumer market is to enable users to use their devices as much as possible.

The increased power of USB-C ports allows consumers to charge their devices faster than ever before, allowing them to use their devices more often without having to connect a charging cable.

■ Pros and Cons

Parallel battery charging using USB-C is already being adopted in many applications and will continue to spread across consumer applications. While USB-C ports and cables offer many advantages to the consumer market in terms of power, cost, and convenience, there are also some drawbacks that can be pointed out.


■ Example of a case using MAX17330

Figure 2 shows a parallel battery charging environment using the MAX17330, which integrates a battery charger, fuel gauge, and protector into a single IC. The MAX17330 enables users to reduce charging times by drawing power from any USB-C-compatible charger or converter and charging parallel battery packs at high speeds.

This configuration also allows for unique battery placement, such as one battery on each side of an AR/VR headset, or one battery on each side of a foldable phone. The chip’s advantages include minimizing voltage drop and heat generation, preventing cross-charging of parallel batteries, and allowing parallel packs to be charged individually.

■ Real-world application examples of MAX17330

Now that we’ve briefly looked at the pros and cons of parallel battery charging using USB-C, and the combination of parallel battery charging and USB-C, let’s look at some real-world application examples.

Parallel battery charging using USB-C is already being introduced in several consumer markets. Examples include AR/VR headsets, cordless drills and other power tools, laptops, and portable tablets. However, when implementing these systems, the challenges mentioned in Table 2 can cause some pain points for design engineers.

Analog Devices provides comprehensive solutions to help ease the challenges design engineers face. For example, the blocks in Figure 2 can be replaced with MAX17330, the USB-C controller position can be replaced with MAX77958, and the downstream source position can be replaced with MAX77986.

The MAX77958 simplifies designs by providing a standalone solution with custom firmware to specify USB-C power delivery levels, while the MAX77986 acts as a downstream source for USB-C to power the rest of the system.

This setup is suitable for applications requiring 15 W or more of power.

For applications requiring less than 15W, the MAX77789, featuring a 1S 3A charger and USB-C protection, is an ideal solution.

Analog Devices offers the MAX17330 EV kit and MAX77789 EV kit to enable users to evaluate the capabilities of these devices. MAX17330 samples for prototyping can be ordered from the samples website. Watch the video 'Introduction to the MAX17330' to learn more about the MAX17330.


■ Parallel battery charging using USB-C, the charging solution for next-generation consumer devices

Today’s consumers want to maximize efficiency and don’t want to waste time charging their devices. By utilizing the Analog Devices products introduced in this article, you can enjoy the benefits of USB-C fast charging and parallel battery packs.

This will maximize efficiency in the final product, extend battery life, and reduce charging times. The consumer market is constantly changing, so design engineers must quickly recognize such changes and find new ways to meet consumer demands.

Parallel battery charging using USB-C could be the solution when looking for new ways to charge the next generation of consumer devices.

※ About the author

Kyle Johnson is an applications engineer in the Central Applications Group at Analog Devices. He holds a BS in Electrical Engineering from Santa Clara University and joined ADI in August 2020. Prior to that, he completed an internship in the Technical Sales team at Maxim Integrated (now ADI).