Smart Battery Management Considerations for Portable Applications

One of the biggest advantages of an intelligent battery management system is the possibility it provides system designers to manage power. Using the information obtained from an intelligent battery management system, the sensitivity of obtaining battery status information can be adjusted. For example, if you know that the battery is empty, you can let the management system provide full load charging current; once the battery is full, you can increase the system sensitivity to determine the end-of-charge point very accurately.

Traditional Approach to Smart Battery Management

Traditional smart battery management methods often use discrete components to implement the application.

An analog-to-digital converter (ADC) is usually used to convert analog functions into digital format. The measured physical parameters (such as current, voltage and temperature) are converted into digital format; then, after processing by the microcontroller, a decision is made based on the system status. If the voltage is out of the specified range or needs to be maintained within the specified range, the information obtained will be sent back to the battery management system to ensure that the portable device can work properly.

This can be achieved using a discrete ADC with a resolution of 12 bits and an accuracy of about 1%. The same process is used when measuring current or temperature. Current and temperature monitoring products are available on the market and can be used to output the correct current and temperature measurement values ​​to the ADC, which converts the input information and provides it to the battery management system for further processing. After processing, the conclusions made in digital format will be converted into an analog format that can be used to control an external physical parameter (such as turning on a charging capacitor or switching the system to a standby state). When it is necessary to save the state of the application before it enters sleep mode, the microcontroller will save the current state of the application to memory before shutting down the system. When the system is re-awakened, the saved state will be extracted from memory and reloaded into the application system, so that the awakened system can resume operation from the point where it was originally exited.

Once the power information is obtained, the application device will then decide what action is necessary based on a pre-set scenario. The application may decide to put an idle device into sleep mode to save power, or to shut down the device in an emergency (such as when the application has exceeded some pre-set limit), or because the system has run out of power and needs to be supplied with more power. Finally, the application may decide that the system has been powered off and needs to be switched to standby. The decision is usually made using an off-the-shelf microcontroller, which is then converted into an analog format and output to the system.

If discrete components are used to implement the various functions of the intelligent battery management system, several devices may be added depending on the complexity of the application. As the system functions increase, the number of system devices increases, and the system design becomes more and more complex. Even so, there is still no solution to the problem of changing system functions or adding functions in the future, so the system cannot be scalable. Although microcontrollers integrate certain functions, such as built-in analog inputs, ADCs and DACs, clock circuits, and CPU cores required to complete decisions, in terms of system scalability, microcontrollers do not have the programmability and flexibility required to support this requirement.

Intelligent battery management using a programmable system-on-chip (PSC)

Figure 1 Fusion device architecture

Another approach to solving the smart battery management problem is to use a platform that has functional integration, flexibility, and scalability. Programmable system chips (PSCs) are becoming more and more widely used. Due to their programmability and flexibility, these chips are becoming more and more prominent in applications that need to be upgraded in the future. The ideal platform should include both analog and digital functions, and the ability to add intelligence in the form of software processor cores. This platform may support all the functions required to build a smart battery management system. The Fusion PSC shown in Figure 1 is such a product, with analog function blocks, multiple analog inputs, and a 12-bit ADC interface with configurable input voltage range adjustment options. The analog block also has multiple monitoring functions for monitoring voltage, current, and temperature. The PSC also includes several clock functions to implement wake-up and standby functions. The optional software processor core for the PSC can implement intelligent processing to control the system to enter sleep mode and wake it up from sleep mode.

Leveraging PSC solutions provides the programmability and flexibility needed to keep pace with battery technology and emerging applications, while reducing overall board size. The ability to integrate several discrete components and functions into a single chip allows designers to significantly reduce board size, power consumption and cost, which is not possible using discrete components.

Conclusion

When choosing an implementation of an intelligent battery management system, one should ensure that the management system allows users to extend the battery life of portable devices while being able to be upgraded at a low cost in the future without major design modifications. Although traditional off-the-shelf components can form an appropriate solution, newer technologies offer greater integration and flexibility and should be considered as viable options. Intelligent battery management will continue to play an important role in portable applications, and as new options become available, designers will be able to more easily implement efficient solutions.

Figure 2 Fusion application circuit