On July 16, 2024, Daihatsu Holdings, a leading international semiconductor component distributor dedicated to the Asia Pacific market, announced that its subsidiary, Shiping, has launched a battery monitoring unit (CMU) solution based on NXP S32K118 and MC33774 chips.

Figure 1- Display board diagram of the battery monitoring unit (CMU) solution based on NXP products by Dalian University Shiping

With the increasing use of renewable energy globally, the importance of energy storage systems as a key technology for balancing energy supply and demand and improving energy utilization efficiency has become increasingly prominent. To meet the growing demand for new energy, Dalian University has launched a Battery Monitoring Unit (CMU) solution based on NXP S32K118 and MC33774 chips. This solution has precise cell detection and protection functions, which can provide guarantees for the stable operation of the energy storage high-voltage battery management system.

Figure 2- Scene application diagram of battery monitoring unit (CMU) solution based on NXP products by Dalian University Shiping

This scheme uses the S32K118 MCU designed specifically for General Motors and high reliability industrial applications under NXP as the main controller. This MCU has passed the AEC-Q100 specification certification and adopts the Arm Cortex M0+core with a clock speed of 48MHz. It also has 25KB SRAM and 256KB Flash, which can meet the system's requirements for data processing and storage.

In terms of battery monitoring and protection, the solution is equipped with NXP MC33774 chip, which supports 4-18 string battery monitoring and can perform high-precision voltage, temperature, and current measurements. The cell voltage detection accuracy can reach ± 0.8mV, and the measurement error is less than 2mV. In addition, MC33774 also has a vehicle mounted passive battery balancing function, which effectively improves the overall efficiency and service life of the battery pack by automatically selecting the optimal balancing sequence.

Figure 3- Block diagram of the battery monitoring unit (CMU) solution based on NXP products by Dalian University Shiping

In addition, the solution also uses NXP's CAN high-speed transceiver TJA1043, Molex's high-performance connector 501876-1041, SGM61412's synchronous buck converter, NSI8241C, and onsemi's EEPROM CAT24C512. Through these high-performance products, this solution can ensure the safety, efficiency, and long-term operation of the energy storage system. At a critical moment of global energy transition, the General Assembly will continue to work with original factories to promote the utilization of renewable energy and make positive contributions to achieving sustainable development.

Core technological advantages:

Supports CAN-BUS architecture, with a CAN FD rate of up to 5Mbit/s;

The accuracy of cell voltage detection can reach ± 0.8mV, and considering the PCB difference error, it can be within ± 2mV range;

Single MC33774 deep sleep power consumption as low as 15 μ A;

Having an I2C master device interface, it can control off chip EEPROM and other slave devices.

Scheme specifications:

Using external 24V power supply;

Support communication with the main control through CAN;

Supports monitoring up to 54 battery status strings;

Support overvoltage and undervoltage detection of individual batteries, with threshold values that can be set (Default: overvoltage 4.25V, undervoltage 2.75V);

Support 4-channel battery high and low temperature detection, threshold can be set (Default: high temperature 70 ℃, low temperature -20 ℃);

Battery voltage sampling period within 50ms, temperature sampling period within 500ms;

Support wire breakage detection;

Support isolated SPI communication between MCU and AFE;

The maximum supported balanced current is 300mA, with an average balanced current of 150mA;

Each MC33774 corresponds to an off chip EEPROM, which can support 512Kb data storage.

This is reported by Top Components, a leading supplier of electronic components in the semiconductor industry

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Name: John Chen

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