JPS604831A - Temperature detection circuit - Google Patents

Abstract

PURPOSE:To enable the detection of the chip temperature of a semiconductor free from the effect of external noise with a stable operation by connecting the semiconductor to an emitter coupled current switching circuit in the combination of various temperature characteristics in the base-to-emitter voltage and resistance. CONSTITUTION:While a low potential signal is applied to a terminal 6, the potential at the terminal 3 becomes so higher than that at the terminal 2 to make a transistor Q2 conducting but a transistor Q1 non-conducting and a low potential signal is outputted to an output terminal 5. The potential at the terminal 3 rises as the temperature of VBE of a transistor Q4 and as the potential at the terminal 2 rises with the sum of changes in the temperature of VBE of diodes D1 and D2, the temperature coefficient becomes steeper than that at the terminal 3. Where the detection temperature is 100 deg.C in the chip junction temperature, the potentials are equal between the terminals 2 and 3 near 100 deg.C in the junction temperature and when the temperature exceeds the level, the terminal 2 gives a high potential to bring the output signal at the terminal 5 upto a high potential. Thus, it can be found that the junction temperature reaches 100 deg.C.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a temperature detection circuit, and more particularly to a temperature detection circuit suitable for use in combination with a binary logic circuit used in information processing.

(2) Description of the prior art Conventionally, the temperature of a semiconductor chip has been measured either outside or on the surface of the chip using a thermometer or similar device, or by measuring the junction voltage of a transistor within the chip and determining the chip temperature from its temperature characteristics. Estimation methods are commonly used. However, the method of measuring externally with a thermometer etc. has problems such as mounting constraints and the accuracy of the measured value, and the method of measuring the junction voltage of transistors inside the chip is unstable and vulnerable to external noise. There were drawbacks such as.

(3) Object of the Invention The object of the present invention is to provide a temperature detection circuit that eliminates the above-mentioned drawbacks of the conventional technology.

(4) Features of the Invention The features of the present invention include first and second transistors forming a differential pair, a constant current circuit connected to commonly connected emitters of the first and second transistors, and a constant current circuit connected to the commonly connected emitters of the first and second transistors. 1st and 2nd
a temperature detection circuit including first and second resistors connected to the collectors of each of the transistors, a diode is connected between the first power supply and the base of the first transistor; A third resistor is connected between a power source and the base of the first transistor, a third transistor is connected between the first power source and the base of the second transistor, and the third resistor is connected between the first power source and the base of the second transistor. The base of the transistor is connected to the collector of the first transistor, and the temperature detection circuit includes a fourth resistor connected between the second power source and the base of the second transistor.

For example, two first
．． a second transistor, the first transistor
There is a so-called current switching type switch circuit U1 configured to selectively allow current to flow through the first and second transistors U1, and resistors 1. Resistor 2 is connected, while diode 1, diode 2, and resistor 3 are all connected in series and inserted between power supply terminal 1 and power supply terminal 2, and the connection point between diode 2 and resistor 3 is connected. is connected to the base of the first transistor, and the base of the second v) transistor is connected to the base of the first transistor.
The emitter of a third transistor whose collector is connected to the power supply terminal 1 is connected, and at the same time, a resistor 4 is connected between the emitter and the power supply terminal 2, and the collector of the first transistor and the third transistor In a current switching type circuit configured such that the base of the second transistor is connected to the constant current circuit U2 and the constant current circuit U2 is also connected, the base of the second transistor is used as an input signal application terminal for initialization, and the base of the second transistor is connected to the constant current circuit U2. This is a temperature detection circuit in which the collector is used as an output terminal for a detection signal.

Then, the constant current source terminal of the constant current circuit U2 is separated from the power supply terminal 2 and made into an independent input terminal, and the normal operation of the temperature detection circuit is confirmed by changing the input voltage applied to the input terminal. It is preferable that it can be confirmed.

In the circuit configured as described above, first, by applying a high-potential initialization signal to the base of the second transistor, the second transistor becomes conductive in the switch circuit U1, and a low-potential detection signal is applied. Output. Both the base potential of the first transistor and the base potential of the second transistor have the characteristic that the potential increases as the chip temperature increases, but the rate of change of the former is larger and is set in terms of the circuit. When the set temperature is reached, the relationship between both base potentials is reversed, the first transistor becomes conductive, and the detection signal changes to a high potential.

(5) Principle and operation of the invention In the emitter-coupled logic circuit configured as described above, each emitter is The base potential of two transistors connected to each other is changed in accordance with fluctuations in the junction temperature of the chip, and a temperature detection signal is output to indicate whether or not the set temperature has been reached.

(6) Embodiment Next, FIG. 1, which is an embodiment of the present invention, will be described. In this figure, Ql, Q2, and Q3 form a constant current emitter-coupled current switching circuit, and ■c
8 is a reference voltage as a constant current source. Dl and D2 are forward diodes using transistors, and the sum of these forward voltages determines the base potential of the transistor Q1.

Q5 is a transistor forming a constant current source, and the product of its constant current value and the resistance value of resistor R1 becomes the base potential of Q4, and the potential obtained by shifting the base-emitter voltage (VB, ) of Q4 is the potential of Q2. It is the base potential. Q6
is an emitter follower transistor for level shifting the initialization signal applied to the terminal 6. Let's follow the operation of the circuit. First, during the period when a low potential signal is applied as an initialization signal to terminal 6, the potential of terminal 3 is higher than that of terminal 2, so transistor Q2 is in a conductive state, and Q1 is in a non-conductive state.
A low potential signal is output to the output terminal 5.

FIG. 2 schematically shows temperature changes related to the potential within the circuit. In this example, a case where the chip junction temperature (TJ) is 100° C. is taken as an example of the detected temperature.

The potential of terminal 3 is approximately Q4's ■B1. ．． The potential of terminal 2 rises with the temperature fluctuations of DI and D2, whereas the potential of terminal 2 rises with the sum of the temperature fluctuations of DI and VBP of D2, so its temperature coefficient has a sharper turning point than that of terminal 3. It is. and'
['j# At 100°C, terminals 2 and 3 have the same potential, and above that range, the potential of terminal 2 is higher.

Therefore, at Tj = 100°C, the output signal at terminal 5 changes from a low potential to a high potential, and the junction temperature of the chip increases to 1.
It can be known from the change in the output signal that the temperature has reached 00°C.

On the other hand, transistor Q5 and resistor R8 that constitute a constant current source
Among them, power supply■. Terminal 10 of resistor 8 connected to
■. . By separating the input voltage from the terminal 10 and varying the input voltage applied to the terminal 10, the detection set temperature (Tj=
It can be confirmed that this circuit operates normally even at temperatures below 1tl)0°C.

(Effects of the Invention) As explained above, the present invention
By skillfully combining the temperature characteristics of the emitter voltage (BF) and the temperature characteristics of the resistance and connecting it to an emitter-coupled current switching circuit, it is possible to check whether the chip temperature exceeds the temperature set in the circuit. This is obtained as a temperature detection signal.

[Brief explanation of the drawing]

FIG. 1 shows an embodiment of the invention. FIG. 2 illustrates temperature fluctuations in potential at each point in the circuit configuration example shown in FIG. 1. In the figure, Ql~QIO...NPN type transistor, Dl,, D2......Diode configuration by NPN type transistor, 几1~R13...
・Resistor, VRI...Reference voltage application terminal, Vc
s: Setting voltage application terminal for constant current source. 1□l 16 For l Figure coffin? figure

Claims (2)

[Claims] (1) First and second transistors forming a differential pair, a constant current circuit connected to commonly connected emitters of the first and second transistors, and each of the first and second transistors In the temperature detection circuit, a diode is connected between a first power source and a base of the first transistor, and a diode is connected between the second power source and the base of the first transistor. A third resistor is connected between the base of the first transistor, a third transistor is connected between the first power supply and the base of the second transistor, and the base of the third transistor is connected between the first power source and the base of the second transistor. is the first
A fourth resistor is connected to the collector of the transistor, and a fourth resistor is connected between the second power supply and the base of the second transistor. (2) The temperature detection circuit according to claim (1), wherein an initialization circuit is connected to the fourth resistor.