Temperature detection device

摘要

A temperature detection device is connected to a temperature sensor, and includes two resistors, a transistor and a microcomputer. The temperature sensor is connected to ground. The resistors are connected in series between the temperature sensor and a power supply line. The transistor is connected to the resistor, which is at the power supply line side. The microcomputer switches over a characteristic of a sensor voltage, which is developed at a junction between the resistor and the temperature sensor, to a first characteristic and a second characteristic by switching over the transistor to an on-state and an off-state. The microcomputer calculates a temperature based on the sensor voltage. When the transistor is in the on-state, the microcomputer detects a voltage developed at a low-potential side output terminal of the transistor and calculates the temperature based on the transistor output voltage and the sensor voltage.

主权项

1. A temperature detection device for a temperature sensor, which is connected to a reference potential line at a low-potential side end thereof and varies resistance thereof with temperature of a detection object, the temperature detection device comprising:
plural resistors including a first resistor and a second resistor, which are connected in series between a high-potential side end of the temperature sensor and a power supply line of a potential higher than the reference potential; a transistor having two output terminals connected to both ends of the second resistor, which is provided at the power supply line side than the first resistor, which is connected to a high-potential side end of the temperature sensor; and a computer including a switch section and a detection section, the switch section switching over a characteristic of a sensor voltage, which is developed at a junction between the first resistor and the temperature sensor, relative to temperature between a first characteristic and a second characteristic by switching over an on-state and an off-state of the transistor, and the detection section detecting the sensor voltage and calculating the temperature based on the sensor voltage, wherein, when the transistor is in the on-state, the detection section detects a transistor output voltage developed at an output terminal, which is a low-potential side of the two output terminals of the transistor, and calculates the temperature based on the transistor output voltage and the sensor voltage.