Low-cost MCU helps battery pack system achieve powerful functions

[Guide]The development of battery technology has given birth to a whole new generation of personal Electronic products. Also benefiting from technological advancements, products with stringent power requirements such as electric tools, electric bicycles and electric cars have also developed tremendously. With large-scale use nowadays, batteries must be safer, more efficient, and smarter than ever before. As people’s functional requirements for smart battery pack systems continue to increase, choosing the right MCU becomes more and more important. In this article, we will conduct an in-depth discussion on the MSP430Tm ecosystem to help readers understand how to use these features to solve the challenges in the battery pack system.

Low-cost MCU helps battery pack system achieve powerful functions

Battery pack overview

For basic lithium battery protection requirements, battery protection ICs such as BQ77915 can be used to ensure that the battery works at its rated temperature and rated current. Some designs require more real-time status information of the battery system to achieve more accurate monitoring and control, which can use battery monitoring ICs such as BQ76952.

Under normal circumstances, high-end battery management ICs will be equipped with microcontrollers (MCUs) for battery management IC configuration, communication, data processing and calculations, as shown in Figure 1.

Low-cost MCU helps battery pack system achieve powerful functions

Figure 1: Block diagram of lithium-ion battery pack

In addition, when the system needs more advanced functions such as power tracking or data logging, the MCU will play a more important role in the system.

Reduce bill of materials with low-cost sensing

Some battery pack solutions may use MCU to detect environmental information (such as temperature). The Smart Analog Combo (SAC) on MSP430FR235x can provide a great help to this type of program. SAC can replace operational amplifiers and other analog signal conditioning components, thereby reducing the bill of materials (BOM). In addition, SAC can achieve signal conditioning and amplification without the use of external circuit components, such as resistors and bias signals, reducing PCB space and reducing costs.

In addition, SAC is a peripheral that can be configured in real time during runtime, so as to realize dynamic optimization and adjustment of the system. For example, SAC has a programmable gain mode that can be configured according to different designs without changing any external components such as feedback resistors. This solution can reduce the number of external components, thereby increasing design flexibility and reducing BOM costs.

In the battery pack system, in addition to temperature detection, SAC can also be configured as a general operational amplifier and used in conjunction with a 12-bit ADC to complete the basic measurement of low-side current.

Improve reliability with high-performance memory

In high-performance battery applications, algorithms based on long-term data (such as running status tracking and charging status tracking) are often required. In an uncertain power supply environment, Flash may be difficult to support frequent recording and low storage latency requirements, and storing data in RAM often involves the risk of data loss due to power failure. However, MSP430 devices with ferroelectric random access memory (FRAM) can easily deal with such challenges. FRAM is a high-performance memory technology that can act as both Flash and RAM at the same time, enabling fast, low-latency, low-power non-volatile storage, and data can be erased by byte, and the number of erases and writes is nearly unlimited. When the battery triggers an over-current or thermal protection circuit, the low-latency, high-speed storage function of FRAM can greatly reduce the possibility of data loss in the event of an unexpected power failure.

Extend battery life with low power consumption performance

Reduced standby power consumption means longer runtimes. The MSP430 device provides a variety of sleep modes, which can meet almost any power supply scenario. Take MSP430FR2355 as an example, its standby current is 620nA, and its shutdown current is 42nA.

The use of SAC also helps to reduce system power consumption. It can be dynamically enabled when needed, and powered off when not needed to reduce power consumption. The traditional signal conditioning technology uses a discrete operational amplifier, which will continue to consume power regardless of whether it is in an effective working state.

TI also provides software analysis tools such as EnergyTrace to observe the dynamic power consumption of the system to facilitate customer debugging and optimization. In addition, Code Composer StudioTm software and the integrated ultra-low power (ULP) Advisor tool in IAR Embedded Workbench can help customers optimize power consumption from a code perspective.

Save development time with a ready-to-use GUI

The development of a completely new system can be a challenging task. The graphical user interface (GUI) provided by the MSP430 team can speed up the development and debugging process of the BQ76952, as shown in Figure 2. Use the MSP430FR2355 LaunchPad development kit with the BQ76952 evaluation module (EVM), and you can learn about important battery data in detail.

Low-cost MCU helps battery pack system achieve powerful functions

Figure 2: MSP+BQ dashboard interface

Concluding remarks

As functional requirements continue to increase, battery systems will tend to have higher energy density, higher safety, and higher on-board intelligence. And choosing the right MCU can help simplify the product development process and speed up the product launch. The diverse MSP430 MCU product portfolio allows you to easily choose the device that meets your needs in terms of performance, power consumption and cost. Check out the links below for product information and technical resources.

The Links:   QM20TD-H LQ084V3DG03 MITSUBISHI-IGBT

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