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  • MM9Z1I638BM2EP Battery Temperature Sensor

  • Created: Aug 05, 2015

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Summary

Most of the rechargeable batteries can operate in a wide temperature range, but it doesn’t mean that we can use or charge them at extreme temperatures. Using a battery at high temperature causes it to overheat and makes the cell dry. Charging it at high temperature or even at cold temperature reduces its ability to accept charges. The battery temperature must be brought into moderate level before using or charging it to avoid damages. Using a temperature sensor, battery temperature can be monitored and regulated by controlling the charging current when the battery temperature is at extreme level.


The MM9Z1I638BM2EP Battery Temperature Sensor reference design is an example of a car battery monitoring system that measures not just the voltage or current but also the temperature level of a battery. In this circuit, the MM9Z1I638BM2EP device measures the battery temperature from an external temperature sensor connected to the PTB3 pin. The resistance of the thermistor R5 varies with respect to the change in the temperature of the battery. The changes in the resistance of R5 create a voltage variation across the PTB3 pin of the MM9Z1I638BM2EP device that serves as a temperature level reference of the battery. The temperature data acquired by the device will be stored into the result registers ACQ_ITEMP and ACQ_ETEMP.


The MM9Z1I638BM2EP device interfaces automotive buses through LIN and msCAN interface. The data from the MM9Z1I638BM2EP device are transmitted to the battery charge controller through the two-wire CAN interface to control the charging/discharging rate of the battery. This circuit design is simple yet ideal for microcontroller based temperature sensing application.