Today, one of the most common choices consumers need to make about the transmission system is to choose a manual or automatic transmission. Drivers are more likely to choose manual transmissions, but automatic transmissions are increasingly popular because of their convenience. The automatic transmission is a large and complex system, which needs to have on-board processing function and maintain normal operation under various driving conditions.

As auto manufacturers continue to seek to provide consumers with more convenient, comfortable and fuel-efficient models, the auto industry is rapidly introducing various new technologies. The most obvious technological innovation is often reflected in the car cab and the on-board information entertainment system, and the car transmission system has also been greatly improved, greatly improving the maneuverability, performance and fuel economy of the vehicle.

The automatic transmission draws the power generated by the automobile engine and then conducts the power through different gear ratios that meet various driving needs. The gear ratio is different to ensure that the engine speed ( RPM ) and torque supplied to the wheels match the current vehicle speed and acceleration. Power from the engine flywheel is transmitted to the transmission through a torque converter.

The transmission control unit ( TCU ) is a high-level control system that manages shift gears based on speed, position, pressure and temperature data reported by the transmission. Due to the need to connect to the engine, the TCU and gearbox are located in or near the engine room. However, when extreme temperatures are reached in the engine room, there is a risk of damage.

The TCU module includes a circuit board with many integrated circuit components, such as a microcontroller ( MCU ) that is very sensitive to high temperatures. Many MCU have some form of integrated temperature sensing function, but they are usually not accurate enough and can only reach a rough approximation of the overall temperature of TCU module.

LM71-Q1 is an external temperature sensor that can directly transmit temperature data to MCU through serial peripheral interface ( SPI ), thus eliminating the need to use analog-to-digital converter channels and/or look-up tables. In addition, LM71-Q1 can monitor the overall temperature of TCU module, and the measurement accuracy can reach + 3/-2 C when the temperature is between-40 C and + 150 C..

As mentioned earlier, TCU uses temperature data from the gearbox as part of its decision-making process. LMT 01-Q1 is an easy-to-use digital temperature sensor in a two-pin lead package that you can install on the gearbox. The wires can be connected to the TCU circuit board by crimping the wires with the leads of the LMT 01-Q1 package. LMT 01 — Q1 transmits temperature data by sending pulses, and MCU/processor counts the pulses.

LMT 01-Q1 has the advantage of always sending bursts, which means that in the event of equipment failure, the missing burst will be a clear signal and therefore cannot continue to measure/transmit temperature data. LMT 01-Q1, which has reached the quality level of automotive supplies, can monitor the temperature of the gearbox, and its measurement accuracy can reach 0.75 C when the temperature is between-40 C and + 150 C..

By optimizing the gear ratio and improving the driver's overall experience, automatic transmission has become an excellent innovation that can save fuel. To ensure the normal operation of the automatic transmission, the temperature of the automatic transmission and TCU needs to be closely monitored.