KR100376225B1 - thermo control circuit for use in coldness and warmness system - Google Patents

Abstract

Disclosed is a thermo control circuit capable of one-chip signal processing of a thermo control circuit suitable for controlling cold and hot equipment such as an air conditioner, a heater, a refrigerator, and one chip of a signal processing unit and a semiconductor temperature sensor. Such a circuit includes: a temperature sensor unit for outputting a sensing voltage signal and a reference voltage signal indicating a result of sensing a temperature by inputting a constant voltage; A constant voltage generation unit connected between an applied power supply voltage and ground to generate the constant voltage, a comparison output unit receiving the constant voltage as an operating power supply voltage, and outputting a comparison signal comparing the sensed voltage signal with a reference voltage signal; A switch circuit for outputting a switching signal in response to the signal, a bias circuit connected between the power supply voltage and the switch unit and outputting a bias voltage in response to the switching signal using a current source independent of the change in the power supply voltage; And by having a one-chip signal processing unit including a drive output unit for outputting a drive signal for controlling the cold and hot appliance in response to the bias voltage, the cost is reduced, the size of the component is reduced and the operation reliability is improved.

Description

Thermo control circuit for use in cold and hot appliances {thermo control circuit for use in coldness and warmness system}

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to integrated circuits, and more particularly to a thermo control integrated circuit suitable for use in cold and hot equipment such as air conditioners, heaters, refrigerators, and the like.

In general, when continuously operating the compressor employed in the air conditioner of the cold and warm equipment there is a problem that the intake of indoor air is blocked by the ice in the indoor air inlet pipe. Therefore, in order to solve such a problem, a thermo sensor is installed in the indoor air inlet to stop the operation of the compressor when the temperature falls below a certain temperature and restart the compressor when the temperature rises above the predetermined temperature. The circuit is mounted.

Conventional thermo control circuit is composed of a sensor unit consisting of a temperature sensor and a housing and a signal processing unit for controlling the operation of the compressor from the temperature information, the sensor unit and the signal processing unit is connected through a long wiring have. Due to the demand for surge characteristics to be solved in automotive electronic components, it is difficult for the thermo control circuit to be one chip. In addition, the sensor unit and the signal processing circuit unit are separated from each other, resulting in poor mountability in terms of size, and poor reliability due to long wirings. In addition, it is difficult to control the precise specifications expected when assembling these parts.

In order to more fully understand the above problem, a conventional thermo control circuit will be described with reference to the accompanying drawings.

In the thermo control circuit shown in FIG. 1, a thermistor (TH) that functions as a temperature sensor is separately inserted into a housing, and the signal processing unit 100 except for the thermistor (TH) includes two OP AMPs 102 and 104. And eight resistors (R1-R8), two transistors (Q2, Q3), three diodes (D1-D3), a zener diode (D4), an electrolytic capacitor (C2), and a ceramic capacitor (C1). . The components of the signal processor 100 are arranged in a connection configuration as shown in FIG. 1 on the PCB substrate.

Referring to the air conditioner of the vehicle to explain the operation of Figure 1 as follows. First, when a voltage flows from the battery of the vehicle through the ignition switch (IGN) and the air conditioner switch (A / C. S / W), a constant constant voltage is induced at the zener diode cathode by the resistor R1 and the zener diode D4. . This voltage becomes a bias between the OP AMP1 102 forming hysteresis and the OP AMP2 104 functioning as a buffer. The constant voltage and constant voltage ratio are formed in the OP AMP1 102 regardless of the temperature by the resistors R3 and R4 having the same temperature coefficient, while the output of the OP AMP2 104 is controlled by the temperature coefficient of the thermistor TH. So change. Accordingly, the external relay RELAY is driven by operating the transistor Q3 through the transistor Q2 when the output of the OP AMP2 104 becomes HIGH at a constant temperature. As a result, the operation of the compressor is stopped. The OP AMP2 104 has a schmitter trigger function.

As described above, the thermo control circuit of FIG. 1 has a signal processing part composed of many components, and thus has a cost increase factor and a large occupied area on the circuit board. In addition, since the thermistor TH is housed separately and connected by a long wire, reliability is a problem and a burden of cost is great.

Therefore, various attempts to one-chip the thermo control circuit have been sought, but one-chip has been difficult for the following reasons. Among these reasons, the first is that it is not easy to protect the circuit from surges, the second is that it is difficult to replace the thermistor with another temperature sensor, and the third is that the chip can easily It will be destroyed.

In addition, it is also very difficult to employ a semiconductor temperature sensor in the thermo control circuit to make the whole one chip. This is because it is difficult to implement a semiconductor temperature sensor that outputs two kinds of voltages having different temperature coefficients in a small size, and it is difficult to correct an error due to self-heating of the temperature sensor.

Accordingly, it is an object of the present invention to provide an improved thermo control circuit which can solve the above-mentioned conventional problems.

Another object of the present invention is to provide a thermo control circuit capable of one-chip signal processor and one-chip signal processor and semiconductor temperature sensor.

It is still another object of the present invention to provide a thermo control circuit with reduced cost, reduced component size, and improved operation reliability.

According to an aspect of the present invention, a thermo control circuit includes: a temperature sensor unit configured to output a sensing voltage signal and a reference voltage signal indicating a result of sensing a temperature by inputting a constant voltage; A constant voltage generation unit connected between an applied power supply voltage and ground to generate the constant voltage, a comparison output unit receiving the constant voltage as an operating power supply voltage, and outputting a comparison signal comparing the sensed voltage signal with a reference voltage signal; A switch circuit for outputting a switching signal in response to the signal, a bias circuit connected between the power supply voltage and the switch unit and outputting a bias voltage in response to the switching signal using a current source independent of the change in the power supply voltage; And a one-chip signal processor including a driving output unit configured to output a driving signal for controlling a cold / hot machine in response to the bias voltage.

According to the above circuit configuration, the cost is reduced due to the one-chip, the size of the component is reduced, and the operation reliability is improved.

1 is a conventional thermo control circuit diagram

2 is a thermo control circuit diagram having a one-chip signal processor according to an embodiment of the present invention.

3 is a circuit diagram showing another embodiment of the temperature sensor unit of FIG.

Hereinafter, the one-chipized thermo control circuit according to a preferred embodiment of the present invention will be described in detail without intending to limit the present invention.

First, Figure 2 shows the configuration of a thermo control circuit according to an embodiment of the present invention. Referring to the drawings, the temperature sensor unit 150 and the signal processing unit 110, and the temperature sensor unit 150 is composed of four resistors (Rex2-Rex5) and thermistor (TH), constant voltage (Vref) ) And outputs the sensing voltage signal Vin- and the reference voltage signal Vin + indicating the result of sensing the temperature. The signal processor 110 is connected between the applied power supply voltage V and ground GND to generate the constant voltage Vref, and receives the constant voltage as an operating power supply voltage. A comparison output unit 112 outputting a comparison signal comparing the reference voltage signal, a switch unit 120 outputting a switching signal in response to the comparison signal, and is connected between the power supply voltage and the switch unit 120. A bias circuit 118 for outputting a bias voltage in response to the switching signal using a current source independent of the change in the power supply voltage, and a relay driving signal for controlling the air conditioner in response to the bias voltage Driving outputs 122 and 124; In addition, the thermal shutdown (TSD) unit 114 is connected between the output terminal of the comparison output unit 112 and the ground and has a function of blocking a circuit when overheating occurs due to a temperature abnormality. The driving output units 122 and 124 are provided with circuit protection diodes D1 and D2 and resistors R1 and R2 for surge input, respectively. When the bias circuit 118 outputs the first and second bias voltages having different voltage levels to the output terminals A and B, the driving output units 122 and 124 each include a PNP and an NPN transistor to drive a relay. A plurality of signals can be output. When it is difficult to employ the regulator 116, a zener diode may be externally used to form a constant voltage. In addition, the drive output units 122 and 124 may be connected to the engine control unit, and the output may be applied to the engine control unit to perform desired control.

The configuration of FIG. 2 is a one-chip of the signal processor 110 only, and the temperature sensor 150 is not included in the one-chip.

When the thermistor of the temperature sensor unit 150 is replaced by another element and implemented in one chip with the signal processing unit 110, the temperature sensor unit 150 of FIG. 2 has a semiconductor temperature as shown in FIG. 3. It can be replaced by a sensor. That is, the semiconductor temperature sensor including a differential amplifier circuit as shown in FIG. When it is changed to the signal processor 110 of Figure 2 and can be implemented in one chip. Thus, the instability of the switching temperature control due to the error between the resistor and the thermistor is solved. The semiconductor temperature sensor unit shown in FIG. 3 is an application design of a semiconductor temperature sensor using a general differential amplifier circuit according to the system of the present invention, and the reference numerals of the terminals shown in FIG. Matching codes are connected to each other in one chip implementation. That is, in Fig. 3, Vin + of terminal 5, which is an output having a negative temperature coefficient, and Vin- of six terminals having a positive temperature coefficient, are respectively connected to the input terminals 5 and 6 of the comparator of Fig. 2, respectively. Conventional general temperature sensor generates a single output, so it was not easy to form a constant reference voltage according to the change of temperature. Even if the reference voltage is generated regardless of the temperature change, it is difficult to satisfy the dispersion of the dispersion and the output voltage of the temperature sensor at the same time. It is difficult to solve and also very disadvantageous in terms of the size of the chip. However, using output voltages having different temperature coefficients as shown in FIG. 3 of the present invention has an advantage of improving detection resolution. In addition, when the influence of self-heating of the signal processing unit on the temperature sensor becomes a problem, the problem caused by the heat-heating can be solved by forming the final output by the pulse width modulation method.

Hereinafter, the function and operation of each unit will be described with reference to FIG. 2. In the figure, the transistors T1 and T2 are connected so that the PNP output method and the NPN output method can be used simultaneously. In addition, by using the current source independent of the supply voltage internally, the output type is prevented from increasing when the external relay is shorted, and the internal temperature caused by the power consumption of the output transistor in case of A Thermal Shut Down (TSD) circuit is built in that detects an increase in the output and turns off the output above a certain temperature, and it is difficult to construct a protection circuit when a short fault occurs in an external relay by the thermal shutdown circuit. Problem is solved.

Then, as shown in FIG. 2, the signal processor 110 is one-chip, thereby solving the problems of cost burden and occupied area. On the other hand, two diodes (D1, D2) are employed using the BV _CBO of the transistor as a method of protection against surge, and in particular, chip breakage that may occur when the reverse connection of Vcc and the ground is a diode (D1). Is prevented by. The use of such diodes is not commonly used in general circuits, but has an excellent effect on the protection of circuits against surges. When a negative surge is applied to the power supply voltage Vcc, the diode D1 withstands a voltage of 80V or more, so the specification required by the automobile manufacturer is satisfied. When a negative surge is applied to the second output Vo2, the diode D2 has a breakdown voltage of 80V or more, so that the requirements are satisfied. When a positive surge is applied to the power supply voltage Vcc, a resistor R2 is inserted between the base and the emitter of the output NPN transistor T3 to increase the voltage of the BV _CEO of the transistor to approximate BV _CBO . This protects the Vo1 output and the path to GND. When a high voltage is applied to GND, the path to Vo1 is protected by forming a breakdown voltage much higher than that of BV _SEO by inserting a resistor R1 between the base and the emitter of the NPN transistor T2 of FIG. 2.

Zener diodes conventionally used for constant voltage formation require high P _D. The 24V battery voltage of a commercial vehicle or the 14V battery voltage also has a normal operating range of 16 to 17V, so the amount of current that a Zener diode must cover is quite large. However, incorporating a Zener diode into an IC is virtually impossible. Therefore, in the present invention, a Zener diode is removed by employing a constant voltage forming regulator 116 as shown in FIG.

In addition, in FIG. 2, the chip size is also minimized by employing a bias circuit 118 that drives an output using a constant current source, omitting the conventional buffer OP AMP.

The basic operation of the relay control in the circuit of FIG. 2 as described above is as follows. When a voltage flows from the battery of the vehicle through the ignition switch (IGN) and the air conditioner switch (A / C. S / W) through the diode D1, the regulator 116 performs a function of a zener diode and thus a constant constant voltage (Vref) Outputs The voltage is used as an operating voltage of the OP AMP 112 and the temperature sensor unit 150.

As shown in FIG. 2, regardless of whether the temperature sensor unit 150 is configured using the thermistor TH and the voltage dividing resistors or the semiconductor temperature sensor as shown in FIG. 3, the comparison output unit in the signal processing unit 110 ( 112 outputs high when the sensed voltage signal applied to the inverting terminal (-) is lower than the reference voltage signal applied to the non-inverting terminal (+). Accordingly, the transistor T4 constituting the switch unit 120 is turned on so that the output terminal A of the bias circuit 118 becomes low and the output terminal B becomes high. Accordingly, the output drivers 122 and 124 respectively output relay driving signals Vo1 and Vo2 for controlling the air conditioner in response to the bias voltage to drive two external relays RELAY. As a result, the operation of the compressor is stopped. In this embodiment, two output drivers are used simultaneously for the PNP output method and the NPN output method, but one output driver can be used.

In the above, a preferred embodiment of the present invention has been described as an example of an air conditioner employed in an automobile, but a person skilled in the art should not be departing from the spirit and scope of the present invention as set forth in the claims below. It will be appreciated that various modifications and variations can be made in the present invention. For example, a thermo control circuit may be employed in the refrigerator or the heater in addition to the air conditioner, and the detailed configuration of the circuit can be appropriately added or decreased according to the case.

According to the present invention as described above, it solved various problems that were difficult to conventionally chip the signal processor and the temperature sensor, there is an effect that the cost is reduced, the size of the parts are reduced, the manufacturing process is shortened, and the operation reliability is improved. .

Claims (14)

In a thermo control circuit suitable for controlling cold and hot equipment: A temperature sensor unit for outputting a sensing voltage signal and a reference voltage signal indicating a result of sensing a temperature by inputting a constant voltage; A constant voltage generation unit connected between an applied power supply voltage and ground to generate the constant voltage, a comparison output unit receiving the constant voltage as an operating power supply voltage, and outputting a comparison signal comparing the sensed voltage signal with a reference voltage signal; A switch circuit for outputting a switching signal in response to the signal, a bias circuit connected between the power supply voltage and the switch unit and outputting a bias voltage in response to the switching signal using a current source independent of the change in the power supply voltage; And a one-chip signal processor including a driving output unit for outputting a driving signal for controlling the cold / hot machine in response to the bias voltage. The circuit of claim 1, wherein the constant voltage generator comprises a regulator or a zener diode, and the drive signal is a drive signal for driving a relay or a drive signal applied to an engine control unit. The circuit of claim 1, wherein the temperature sensor unit comprises a semiconductor temperature sensor configured as a differential amplifier circuit to be one-chip with the signal processor. 2. The circuit according to claim 1, further comprising a thermal shutdown circuit for circuit protection between an output terminal of the comparison output section and a ground. The circuit of claim 1, further comprising a circuit protection diode and a resistor for a surge input in the driving output unit. The circuit of claim 1, wherein the bias circuit outputs first and second bias voltages having different voltage levels. The circuit of claim 6, wherein the driving output unit comprises a PNP and an NPN transistor, respectively, and outputs a plurality of relay driving signals. In a thermo control circuit that controls the air conditioner's on / off relay in response to temperature changes: A semiconductor temperature sensor unit incorporating a differential amplifier circuit and outputting a sensing voltage signal and a reference voltage signal indicating a result of sensing a temperature without using a thermistor; A regulator connected between an applied power supply voltage and ground to generate the constant voltage, a comparison output unit for receiving the constant voltage as an operating power supply voltage, and outputting a comparison signal comparing the sensed voltage signal with a reference voltage signal; A switch circuit for outputting a switching signal in response; a bias circuit connected between the power supply voltage and the switch unit and outputting a bias voltage in response to the switching signal using a current source that is independent of the change in the power supply voltage; And a signal processing unit including a driving output unit outputting a relay driving signal for controlling the air conditioner in response to a bias voltage. And the semiconductor temperature sensor portion and the signal processing portion are formed as integrated circuits in the same chip. 9. The circuit according to claim 8, further comprising a thermal shutdown circuit for circuit protection between an output terminal of the comparison output section and a ground. 9. The circuit of claim 8, further comprising a circuit protection diode and a resistor for a surge input in the driving output unit. The circuit of claim 8, wherein the bias circuit outputs first and second bias voltages having different voltage levels. The circuit of claim 11, wherein the driving output unit includes a PNP and an NPN transistor, respectively, and outputs a plurality of relay driving signals. The circuit of claim 8, wherein the semiconductor temperature sensor unit is configured to simultaneously output voltage signals each having a negative temperature coefficient and a positive temperature coefficient by embedding a differential amplifier. The circuit of claim 8, wherein the semiconductor temperature sensor unit performs temperature sensing by adjusting a switching voltage of voltage signals having negative and positive temperature coefficients, respectively, by using a trimming resistor.