Fast-response thermistors for lithium battery packs

Littelfuse's TTape platforms expand Rutronik's thermistor portfolio. The devices were developed for thermal monitoring of multi-cell lithium-ion batteries and large-area temperature monitoring in critical applications, requiring only one MCU input. Compared to traditional NTC thermistors, they provide particularly high accuracy and very fast response in the event of overheating. The AEC-Q200-certified platforms help extend battery life. They are quick and easy to install and can be integrated into existing BMS without additional calibration.

The operation of lithium-ion batteries requires accurate thermal monitoring to ensure safe operating conditions and optimise battery charging performance.

With the TTape platforms, Littelfuse provides the option of placing many measuring points in a multi-cell battery pack. This increases the spatial resolution of temperature monitoring and simplifies the installation process.

Using a two-wire interface, their sensors detect localised cell overheating: they activate at a temperature of 58C +/- 3C and reset at a temperature of 42C +/- 3C. Standard NTC temperature sensors only detect thermal runaway in the specific cell to which they are attached. TTape, on the other hand, impresses with an ultra-fast response time of less than one second when any cell in the whole battery pack overheats. This significantly decreases the time it takes for the BMS to initiate countermeasures, making thermal management easier and more efficient.

The signal can also be employed as a watchdog to wake the MCU from sleep mode in the event of overheating. By monitoring each battery cell, the TTape platform helps to meet safety requirements and prevent thermal runaways.

Benefits at a glance:

• Voltage supply range VDD: 3.3-5.5V
• Pull-up resistor RP: 200kΩ (±5%)
• Voltage Vmax: 6V
• Maximum current Imax: 6mA
• Extremely fast response time of less than one second
• No calibration required
• Extremely thin design
• AEC-Q200 certified
• Quick and easy installation

Application examples include large-area distributed temperature monitoring and temperature monitoring of lithium-ion batteries.