JP5729544B2 - Temperature detection circuit - Google Patents

Description

  The present invention relates to a temperature detection circuit.

  2. Description of the Related Art Conventionally, there have been known devices and systems that incorporate a temperature sensor and a microcomputer, and the microcomputer performs temperature compensation of various data using temperature information output from the temperature sensor. Many of the temperature sensors generate an analog voltage including temperature information using the temperature characteristics of the band gap and the resistance of the PN junction. On the other hand, since a microcomputer performs digital processing, temperature information of a digital value is required. For this reason, analog temperature information is converted into a digital value by an AD conversion circuit and then input to a microcomputer, or a microcomputer incorporating an AD conversion circuit is used. Alternatively, a digital output temperature sensor incorporating an AD conversion circuit may be used (Patent Document 1).

Special table 2008-513766 gazette

  However, the conventional digital output temperature sensor requires a bandgap reference circuit and an ADC circuit, so that there is a problem that current consumption is large and the circuit size is large.

  The present invention has been made in view of the above problems, and according to some aspects of the present invention, temperature detection capable of generating digital temperature information with smaller power consumption and circuit size than conventional ones. A circuit can be provided.

  (1) In the present invention, a resistance portion in which a plurality of resistors including at least two types of resistors having different resistance temperature characteristics between two power supplies are connected in series, and voltages at a plurality of connection points of the resistance portions are A voltage selection unit that selects one voltage from the voltages at the plurality of connection points according to a selection signal, a voltage comparison unit that compares a voltage selected by the voltage selection unit with a certain reference voltage, and the voltage In accordance with the comparison result of the comparison unit, the selection signal is sequentially changed so that the voltage selected by the voltage selection unit approaches the reference voltage, and a digital code representing temperature information is generated based on the selection signal. And a temperature information code generation unit.

  In the temperature detection circuit of the present invention, since the resistance portion includes at least two types of resistors having different temperature characteristics, the voltage at each connection point obtained by dividing the resistance between the two power sources varies depending on the temperature. Then, since the voltage finally selected by the voltage selection unit by the temperature information code generation unit becomes a voltage at a connection point closer to a certain reference voltage, the selection signal for selecting this voltage includes temperature information and is simple. Digital temperature information can be generated from this selection signal by a simple circuit. That is, according to the temperature detection circuit of the present invention, a band gap reference circuit and an AD conversion circuit are not required, and by appropriately selecting the resistance value of each resistance of the resistance unit, the power consumption and circuit size can be reduced compared to the conventional one. can do.

  (2) In this temperature detection circuit, the resistance unit is a resistor having a positive temperature characteristic in which at least one of the plurality of resistors has a higher resistance value as the temperature is higher, and at least another of the plurality of resistors. One may be a resistor having a negative temperature characteristic in which the resistance value decreases as the temperature increases.

  In this way, the direction of change in resistance value with respect to temperature change is reversed with respect to at least two resistors included in the resistance part, so that the amount of change in voltage at each connection point of the resistance part with respect to temperature change is further increased. be able to. Thereby, temperature detection sensitivity can be improved.

  (3) In this temperature detection circuit, the resistor section may include a first switch for bypassing at least one of the plurality of resistors.

  In this way, since the overall resistance value of the resistor section changes by turning on / off the first switch, the voltage at each connection point obtained by dividing the resistance between the two power sources can be changed. Thereby, the offset of temperature information can be corrected to some extent.

  (4) In this temperature detection circuit, the resistor section may include a second switch for switching at least one of the plurality of resistors to another resistor having a different resistance temperature characteristic.

  In this way, by changing the second switch, the amount of change in the voltage at each connection point of the resistance section with respect to the temperature change changes, so the change rate (slope) of temperature information, that is, the temperature detection sensitivity can be adjusted. Can do.

(5) The temperature detection circuit, based on the compensation bit information, the digital code by the temperature information code generation unit generates may further include a temperature information code correcting unit for correcting.

  In this way, the offset of the temperature information can be corrected accurately.

The functional block diagram of the temperature detection circuit of 1st Embodiment. The figure which shows the structural example of the temperature detection circuit of 1st Embodiment. The figure which shows the structural example of the bit adjustment circuit of 1st Embodiment. The figure which shows an example of the truth table of a decoder. The figure which shows an example of the truth table of a multiplexer. The flowchart figure which shows an example of operation | movement of a successive approximation circuit. The figure which shows an example of the timing chart of temperature detection operation | movement. The functional block diagram of the temperature detection circuit of 2nd Embodiment. The figure which shows the structural example of the temperature detection circuit of 2nd Embodiment. The figure which shows the structural example of the bit adjustment circuit of 2nd Embodiment. The figure which shows an example of the temperature characteristic of the output code of a temperature detection circuit.

  DESCRIPTION OF EMBODIMENTS Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the drawings. The embodiments described below do not unduly limit the contents of the present invention described in the claims. Also, not all of the configurations described below are essential constituent requirements of the present invention.

1. First Embodiment FIG. 1 is a functional block diagram of a temperature detection circuit according to a first embodiment. The temperature detection circuit 1 of the present embodiment includes a resistance unit 10, a voltage selection unit 20, a voltage comparison unit 30, a temperature information code generation unit 40, and a temperature information code correction unit 50. Note that the temperature detection circuit 1 of the present embodiment may have a configuration in which some of these configurations (elements) are omitted.

  In the resistor unit 10, a plurality of resistors 12 including at least two types of resistors having different temperature characteristics of resistance values are connected in series between two power sources. For example, the resistance unit 10 is a resistor having a positive temperature characteristic in which at least one of the plurality of resistors 12 has a higher resistance value as the temperature is higher, and at least one of the plurality of resistors 12 is higher as the temperature is higher. It is a resistor having a negative temperature characteristic in which the resistance value is lowered.

  The resistor unit 10 may include a first switch 15 for bypassing at least one of the plurality of resistors 12. There may be one or more first switches 15.

  The voltage selection unit 20 receives voltages 14-1 to 14 -n at a plurality of connection points of the resistance unit 10, and the voltages 14-1 to 14 -n at the plurality of connection points 1 to 1 according to the selection signal 44 The process of selecting is performed.

  The voltage comparison unit 30 performs a process of comparing the voltage 22 selected by the voltage selection unit 20 with a constant reference voltage 34 without depending on the temperature.

  The temperature information code generation unit 40 sequentially changes the selection signal 44 so that the voltage 22 selected by the voltage selection unit 20 approaches the reference voltage 34 according to the comparison result 32 of the voltage comparison unit 30. The digital code 42 representing the temperature information is generated based on the above.

  The temperature information code correction unit 50 performs a process of generating the digital code 52 by correcting the digital code 42 generated by the temperature information code generation unit 40 based on the given correction bit information 54.

  FIG. 2 is a diagram illustrating a configuration example of the temperature detection circuit according to the first embodiment. As shown in FIG. 2, the temperature detection circuit 1 of the first embodiment includes a bit adjustment circuit 110, 64 resistors 120-0 to 120-63 (an example of the resistor 12 in FIG. 1), and a resistor 122 (in FIG. 1). 1), multiplexer 200 (an example of voltage selection unit 20 in FIG. 1), comparator 300 (an example of voltage comparison unit 30 in FIG. 1), reference voltage generation circuit 310, and successive approximation circuit 400 (in FIG. 1). An example of the temperature information code generation unit 40) and a digital adjustment circuit 500 (an example of the temperature information code correction unit 50 in FIG. 1) are included. Note that the temperature detection circuit 1 of the present embodiment may have a configuration in which some of these configurations (elements) are omitted.

  FIG. 3 shows a configuration example of the bit adjustment circuit 110. The bit adjustment circuit 110 of this embodiment includes 15 resistors 112-1 to 112-15 (an example of the resistor 12 in FIG. 1) connected in series between the power supply voltage VDD and the resistor 120-0 (see FIG. 2). ), 15 switches 114-1 to 114-15 (an example of the first switch 15 in FIG. 1), and a decoder 116. The resistors 112-1 to 112-15 are connected in series between the power supply voltage VDD and the resistor 120-0 (see FIG. 2), and the switches 114-1 to 114-15 are respectively connected to the resistors 112-1 to 112-1. 112-15 is connected in parallel. In the present embodiment, the resistors 112-1 to 112-15 are resistors having negative temperature characteristics in which the resistance value decreases as the temperature increases, and are realized by, for example, poly resistors.

The decoder 116 controls control signals S _{1 to} S _{15 for} controlling opening / closing (on / off) of the switches 114-1 to 114-15 according to a 4-bit adjustment code CALB_A [3: 0] supplied from the outside. Is generated. FIG. 4 shows an example of the truth table of the decoder 116. In the example of FIG. 4, when the value of CALB_A [3: 0] is 0000 (decimal number 0), the control signals S _{1 to} S ₁₅ turn off the switches 112-1 to 112-15, respectively (all the switches are turned off). When the value of CALB_A [3: 0] is 1111 (decimal number 15), the control signals S _{1 to} S ₁₅ turn on the switches 112-1 to 112-15 (all the switches are turned on). Further, when the value of CALB_A [3: 0] is 0001 to 1110 (decimal 1 to 14), the control signals S _{1 to} S _N switch the switches 112-1 to 112-N for each value N. The control signals S _{N + 1 to} S ₁₅ turn off the switches 112-N + 1 to 112-15, respectively. That is, by changing the value of CALB_A [3: 0], the resistance value between the power supply voltage VDD and the resistor 120-0 (see FIG. 2) (hereinafter referred to as “the resistance value of the bit adjustment circuit 110”) is changed. Can be done.

  Note that the initial value of CALB_A [3: 0] is, for example, 0111, and the switches 114-1 to 114-15 are in the state shown in FIG. 3 (switches 114-1 to 114-7 are on, switches 114-8 to 114-15 is off). Then, by changing CALB_A [3: 0] to a value larger than the initial value, the resistance value of the bit adjustment circuit 110 is increased, and by changing CALB_A [3: 0] to a value smaller than the initial value, the bit is changed. The resistance value of the adjustment circuit 110 can be lowered.

  2 and 3, the resistors 112-1 to 112-15, resistors 120-0 to 120-63, and resistor 122 of the bit adjustment circuit 110 are connected in series between the power supply voltage VDD and the ground voltage VSS. This corresponds to the resistor 10 in FIG. The resistors 120-0 to 120-63 and the resistor 122 are resistors having positive temperature characteristics in which the resistance value increases as the temperature increases, and are realized by, for example, diffused resistors.

In such a configuration, the resistance value of the resistor 120-i (i = 0 to 63) at VSS = 0V and the reference temperature T ₀ (for example, 25 ° C.) is Rp _i , the resistance value of the resistor 122 is Rp _base , and bit adjustment When the resistance value of the circuit 110 is Rm _base , each voltage V _x (x = 0 to 63) at the temperature T is calculated by the following equation (1). In Equation (1), the first-order temperature coefficient of the resistors 120-0 to 120-63 is tcl _rp (> 0), and the first-order temperature coefficient of the resistors 112-1 to 15-15 is tcl _rm (<0). It is assumed that the second and higher temperature coefficients are negligible.

Since tcl _rp > 0 and tcl _rm <0, from equation (1), the higher the temperature T, the higher the voltages V _x (x = 0 to 63).

The multiplexer 200 connects the connection point between the bit adjustment circuit 110 and the resistor 120-0 (the connection point between the resistor 112-15 and the resistor 120-0) according to the 6-bit code DA [5: 0] generated by the successive approximation circuit 400. voltage _{V 0} which), the voltage _{V 1} of the connection point of the resistors 120-0 and resistor 120-1, the voltage _V 2 of the connection point resistor 120-1 and a resistor 120-2, ..., resistors 120-61 and the resistor One of the voltage V _{62 at} the connection point 120-62 and the voltage V ₆₃ at the connection point between the resistors 120-62 and 120-63 is selected and supplied to the inverting input terminal of the comparator 300 as the selection voltage V _mux. To do. FIG. 5 shows an example of the truth table of the multiplexer 200. In the example of FIG. 5, when the decimal value of DA [5: 0] is x (x = 0 to 63), V _mux = V _x .

The reference voltage generation circuit 310 is configured by connecting two resistors 312 and 314 having the same resistance temperature characteristic in series between the power supply voltage VDD and the ground voltage VSS, and the resistance ratio of the resistor 312 and the resistor 314 is determined. The reference voltage V _ref is generated by the corresponding voltage division. Since the temperature characteristics of the resistance values of the resistors 312 and 314 are the same, the resistance ratio between the resistors 312 and 314 is constant even when the temperature changes. Therefore, the reference voltage V _ref is constant regardless of the temperature.

In the comparator 300, the selection voltage V _mux of the multiplexer 200 and the reference voltage V _ref generated by the reference voltage generation circuit 310 are supplied to the inverting input terminal and the non-inverting input terminal, respectively, and in synchronization with the clock signal MCLK, When V _mux is higher than V _ref, VSS is output, and when V _mux is lower than V _ref , a signal CMP that is VDD is output.

The successive approximation circuit 400 increases the value of the 6-bit code DA [5: 0] in synchronization with the clock signal MCLK if the output signal CMP of the comparator 300 is low level (V _mux is higher than V _ref ). If the output signal CMP of the comparator 300 is at a high level (V _mux is lower than V _ref ), the value of the 6-bit code DA [5: 0] is decreased so that V _mux approaches V _ref. To control. Then, the successive approximation circuit 400 searches for a value of DA [5: 0] that V _mux is closest to V _ref, and sets the search result DA [5: 0] to a 6-bit output code D [5: 0]. set.

For example, the successive approximation circuit 400 may perform a binary search for V _mux close to V _ref according to the flowchart shown in FIG. 6. That is, first, DA [5: 0] is initially set to the intermediate value 32 (S10). If CMP is at a high level (Y in S20), 16 is subtracted from DA [5: 0] (S30). Is 16 (N in S20), 16 is added to DA [5: 0] (S32). Next, if CMP is high level (Y of S40), 8 is subtracted from DA [5: 0] (S50), and if CMP is low level (N of S40), 8 is set to DA [5: 0]. Are added (S52). Next, if CMP is at a high level (Y in S60), 4 is subtracted from DA [5: 0] (S70). If CMP is at a low level (N in S60), 4 is added to DA [5: 0]. Are added (S72). Next, if CMP is at a high level (Y in S80), 2 is subtracted from DA [5: 0] (S90), and if CMP is at a low level (N in S80), 2 is added to DA [5: 0]. Are added (S92). Next, if CMP is at a high level (Y in S100), 1 is subtracted from DA [5: 0] (S110). If CMP is at a low level (N in S100), 1 is set to DA [5: 0]. Are added (S112). Next, if CMP is at a high level (Y in S120), 1 is subtracted from DA [5: 0] (S130). Finally, DA [5: 0] is set to the output code D [5: 0] (S140).

  The digital adjustment circuit 500 adds the 4-bit correction code CALB_D [3: 0] (−8 to +7) to the 6-bit output code D [5: 0] of the successive approximation circuit 400 in synchronization with the clock signal MCLK. As a result, the corrected 6-bit code DCAL [5: 0] is generated and output. Specifically, a 7-bit addition result SUM [6: 0] is generated by sign-extending and adding D [5: 0] and CALB_D [3: 0] to a 7-bit code, and SUM [5 :: 0] is set to DCAL [5: 0]. However, as a countermeasure against overflow, if SUM [6] = 1 and CALB_D [3] = 0, DCAL [5: 0] = 63, and if SUM [6] = 1 and CALB_D [3] = 1, DCAL [5 : 0] = 0.

As described above, the resistance value of the bit adjustment circuit 110 changes according to the set value of CALB_A [3: 0], and the voltage V ₁ can be obtained by changing the resistance value Rm _base of the bit adjustment circuit 110 from Equation (1). it is possible to change the value of ~V _63. The successive approximation circuit 400 sets the value of DA [5: 0] that V _mux is closest to V _ref to the 6-bit output code D [5: 0], and CALB_A [3: 0]. ] Appropriately, rough adjustment can be performed so that D [5: 0] is as close to 32 as possible at a reference temperature T ₀ (for example, 25 ° C.). In the present embodiment, rough adjustment is performed so that D [5: 0] becomes any value in the range of 32 ± 7 at the reference temperature T ₀ (for example, 25 ° C.). Since the digital adjustment circuit 500 adds the correction code CALB_D [3: 0] of −8 to +7 to D [5: 0], the reference temperature is set by appropriately setting CALB_D [3: 0]. Fine adjustment can be made so that DCAL [5: 0] becomes 32 at T ₀ (for example, 25 ° C.).

By the way, the values of the voltages V _{1 to} V ₆₃ become higher as the temperature becomes higher according to the equation (1). That is, the voltage closest to V _ref among the voltages V _{1 to} V ₆₃ changes according to the temperature. As a result, DCAL [5: 0] increases as the temperature increases and decreases as the temperature decreases, and the temperature detection circuit 1 of the present embodiment functions as a temperature sensor.

  Note that the comparator 300 and the successive approximation circuit 400 operate only when the enable signal EN is active (for example, high level), and stop operating when the enable signal EN is inactive (for example, low level). Thereby, power consumption can be reduced.

FIG. 7 is a diagram illustrating an example of a timing chart of the temperature detection operation by the temperature detection circuit 1. In the example of FIG. 7, coarse adjustment is performed so that D [5: 0] becomes 35 at a reference temperature T ₀ (for example, 25 ° C.), and the setting is set to CALB_D [3: 0] = − 3. 0] is finely adjusted to 32, and the temperature detection operation when the temperature is slightly higher than the reference temperature T ₀ (for example, 25 ° C.) is shown.

As shown in FIG. 7, by changing the enable signal EN from the low level (inactive) to a high level (active) at time t _0, a temperature detection operation by the temperature detection circuit 1 starts. Synchronously at time _{t 1} with the rise of the clock signal MCLK, DA [5: 0] is initialized to 32 (S10 in FIG. 6). As a result, the selection voltage V _mux of the multiplexer 200 becomes V ₃₂ . Since V ₃₂ <V _{ref at} the rise of the clock signal MCLK at time t _2, the output signal CMP of the comparator 300 remains at a low level.

Next, the CMP is low, in synchronization at time _{t 3} to the rise of the clock signal MCLK, DA [5: 0] is set to 48 (= 32 + 16) ( S32 in FIG. 6). As a result, the selection voltage V _mux of the multiplexer 200 becomes V ₄₈ . Since V ₄₈ > V _{ref at} the rise of the clock signal MCLK at time t _4, the output signal CMP of the comparator 300 changes from low level to high level.

Next, the CMP is high level, in synchronization with the rising edge of the clock signal MCLK at time _{t 5, DA [5: 0} ] is set to 40 (= 48-8) (S50 in FIG. 6). As a result, the selection voltage V _mux of the multiplexer 200 becomes V ₄₀ . Since V ₄₀ > V _{ref at} the rise of the clock signal MCLK at time t _6, the output signal CMP of the comparator 300 remains at a high level.

Next, the CMP is high level, in synchronization at time _{t 7} to the rise of the clock signal MCLK, DA [5: 0] is set to 36 (= 40-4) (S70 in FIG. 6). As a result, the selection voltage V _mux of the multiplexer 200 becomes V ₃₆ . Since V ₃₆ <V _{ref at} the rising edge of the clock signal MCLK at time t _8, the output signal CMP of the comparator 300 changes from high level to low level.

Next, the CMP is low, in synchronization at time _{t 9} to the rise of the clock signal MCLK, DA [5: 0] is set to 38 (= 36 + 2) ( S92 in FIG. 6). As a result, the selection voltage V _mux of the multiplexer 200 becomes V ₃₈ . Since V ₃₈ > V _{ref at} the rise of the clock signal MCLK at time t _10, the output signal CMP of the comparator 300 changes from low level to high level.

Next, the CMP is high level, in synchronization at time _{t 11} to the rising edge of the clock signal MCLK, DA [5: 0] is set to 37 (= 38-1) (S110 in FIG. 6). As a result, the selection voltage V _mux of the multiplexer 200 becomes V ₃₇ . Since V ₃₇ > V _{ref at} the rising edge of the clock signal MCLK at time t _12, the output signal CMP of the comparator 300 remains at a high level.

Next, the CMP is high level, in synchronization at time _{t 13} to the rising edge of the clock signal MCLK, DA [5: 0] is set to 36 (= 37-1) (S130 in FIG. 6). As a result, the selection voltage V _mux of the multiplexer 200 becomes V ₃₆ .

Finally, in synchronization at time _{t 14} to the falling edge of the clock signal MCLK, the output code D of the successive approximation circuit 400 [5: 0] after it that have been updated from 35 36 (S140 in FIG. 6), the digital adjustment circuit The output code DCAL [5: 0] of 500 is updated from 32 (= 35-3) to 33 (= 36-3).

As described above, in the temperature detection circuit according to the first embodiment, a plurality of resistors (112-1 to 112-15) having a negative temperature coefficient and a plurality having a positive temperature coefficient are between VDD and VSS. Since the resistors (120-0 to 120-63, 122) are connected in series, the voltages V _{0 to} V _{63 at} each connection point change according to the temperature. Then, the successive approximation circuit 400, since the selection voltage _{V mux} of the multiplexer 200 becomes a voltage closest to the reference voltage _{V ref} below the reference voltage _{V ref,} the code DA selecting this voltage [5: 0] is temperature information Is included. And according to the temperature detection circuit of 1st Embodiment, a band gap reference circuit and an AD converter circuit are unnecessary, and resistance of each resistance (112-1 to 112-15, 120-0 to 120-63, 122) By appropriately selecting the values, it is possible to reduce the power consumption and the circuit size as compared with the prior art.

Further, according to the temperature detection circuit of the first embodiment, a plurality of resistors (112-1 to 112-15) having a negative temperature coefficient and a plurality of resistors (120-0 to 120-63) having a positive temperature coefficient. 122), the direction of change of the resistance value with respect to the temperature change is reversed, so that the amount of change in the voltages V _{0 to} V ₆₃ at each connection point with respect to the temperature change can be further increased. Thereby, temperature detection sensitivity can be improved.

Further, according to the temperature detection circuit of the first embodiment, the resistance value of the bit adjustment circuit changes depending on the on / off of the switches 114-1 to 114-15. The voltages V _{0 to} V ₆₃ at the connection point can be adjusted. Thereby, the offset of the code D [5: 0] (difference from the reference value (32) at the reference temperature T ₀ ) can be roughly adjusted. Furthermore, the fine adjustment by the digital adjustment circuit 500 makes it possible to completely cancel the offset of the output code DCAL [5: 0].

2. Second Embodiment FIG. 8 is a functional block diagram of a temperature detection circuit according to a second embodiment. The temperature detection circuit 1 of the present embodiment includes a resistance unit 10, a voltage selection unit 20, a voltage comparison unit 30, a temperature information code generation unit 40, and a temperature information code correction unit 50. Note that the temperature detection circuit 1 of the present embodiment may have a configuration in which some of these configurations (elements) are omitted. In the temperature detection circuit of the second embodiment, the resistance unit 10 includes a second switch 16 for switching at least one of the plurality of resistors 12 to another resistor 13 having a different temperature characteristic of the resistance value. There may be one or more second switches 16. The other configuration in FIG. 8 is the same as the temperature detection circuit of the first embodiment shown in FIG.

  FIG. 9 is a diagram illustrating a configuration example of the temperature detection circuit of the second embodiment. As shown in FIG. 9, the temperature detection circuit 1 of the second embodiment includes a bit adjustment circuit 110, 64 resistors 120-0 to 120-63, a resistor 122, a resistor 124, a switch 126, a multiplexer 200, and a comparator. 300, a reference voltage generation circuit 310, a successive approximation circuit 400, and a digital adjustment circuit 500. Note that the temperature detection circuit 1 of the present embodiment may have a configuration in which some of these configurations (elements) are omitted. In the temperature detection circuit of the second embodiment, a resistor 124 (an example of the resistor 13 of FIG. 8) and a switch 126 (the second switch 16 of FIG. 8) are compared to the temperature detection circuit of the first embodiment shown in FIG. 1) is added, the configuration of the bit adjustment circuit 110 is different, and the other configurations are the same. The description of the same configuration as that of the first embodiment is omitted.

The resistor 124 has a resistance value equal to that of the resistor 124 at a reference temperature T ₀ (for example, 25 ° C.), but has a temperature characteristic different from that of the resistor 124. While the resistor 122 has a positive temperature characteristic, the resistor 124 may have a positive temperature characteristic having a temperature coefficient different from that of the resistor 122, or may have a negative temperature characteristic. For example, the resistor 122 may be realized by a diffused resistor, and the resistor 124 may be realized by a well resistor or a poly resistor.

In the temperature detection circuit 1 of the second embodiment, the switch 126 is controlled by the control signal SEL_RP, so that either the resistor 122 or the resistor 124 can be selected and connected between the resistor 120-63 and the ground. Yes. At the reference temperature T ₀ (for example, 25 ° C.), the resistance value does not change even when the switch 126 is switched. However, at the temperature other than the reference temperature T ₀ (for example, 25 ° C.), the resistance value changes by switching the switch 126.

FIG. 10 shows a configuration example of the bit adjustment circuit 110 in the second embodiment. As shown in FIG. 10, the bit adjustment circuit 110 of the second embodiment is different from the bit adjustment circuit of the first embodiment shown in FIG. 3 in that a resistor 113 (an example of the resistor 13 in FIG. 8) and a switch 115 ( An example of the second switch 16 in FIG. 8 is added, and the other configurations are the same. The description of the same configuration as in the first embodiment is omitted. The resistor 113 has a resistance value at a reference temperature T ₀ (for example, 25 ° C.) equal to that of the resistor 112-15, but has a temperature characteristic different from that of the resistor 112-15. While the resistor 112-15 has a negative temperature characteristic, the resistor 113 may have a positive temperature characteristic, or may have a negative temperature characteristic having a temperature coefficient different from that of the resistor 112-15. May be. For example, the resistor 112-15 may be realized by a poly resistor, and the resistor 113 may be realized by a diffused resistor or a well resistor.

In the bit adjustment circuit 110 according to the second embodiment, when the switch 114-15 is off, the switch 115 is controlled by the control signal SEL_RM, so that either the resistor 113 or the resistor 112-15 is selected. 14 and the resistor 120-0 can be connected. Reference temperature _{T 0} (for example 25 ° C.) in does not change the resistance value of the bit adjustment circuit 110 also switches the switch 115, at the reference temperature _{T 0} (for example 25 ° C.) temperatures other than the bit adjustment by switching the switch 115 The resistance value of the circuit 110 changes.

With such a configuration, the temperature detection circuit 1 of the second embodiment, by switching at least one switch 115 and the switch 126, so it is possible to change the rate of change of the voltage V _x to the temperature change Yes. For example, if the resistor 124 has a positive temperature coefficient that is greater than the temperature coefficient of the resistor 122, the selection of the switch 126 is switched from the resistor 122 to the resistor 124 while the selection of the switch 115 is fixed to the resistor 112-15. the absolute value of tcl _rp of (1) to become substantially larger, the change rate of the voltage V _x to the temperature change is increased. For example, when the resistor 113 has a positive temperature coefficient, the selection of the switch 115 is switched from the resistor 112-15 to the resistor 113 while the selection of the switch 126 is fixed to the resistor 122, so that tcl _{rm in the} equation (1) absolute value of to become substantially smaller, the rate of change of the voltage V _x to the temperature change is reduced.

  That is, by switching at least one of the switch 115 and the switch 126, the slope (rate of change) of the output code DCAL [5: 0] of the temperature detection circuit 1 with respect to the temperature can be changed. For example, as shown in FIG. 11, when an output code DCAL [5: 0] having a characteristic (a one-dot chain line characteristic) whose inclination is smaller than the characteristic indicated by the solid line due to process variation is obtained. By switching the selection of 126 from the resistor 122 to the resistor 124 having a larger temperature coefficient, the characteristics of the solid line can be approximated. In addition, when DCAL [5: 0] having a characteristic that is larger than the characteristic indicated by the solid line (the characteristic of the two-dot chain line) is obtained, the switch 115 is selected from the resistor 112-15 with a positive temperature coefficient. By switching to the resistor 113, it is possible to approach the characteristics of the solid line.

According to the temperature detection circuit of the second embodiment described above, the same effect as that of the first embodiment can be obtained. Furthermore, according to the temperature detection circuit of the second embodiment, by changing the switch 115 and the switch 126, the amount of change in the voltages V _{0 to} V ₆₃ at each connection point with respect to the temperature change changes, so the output code DCAL [5: 0] with respect to temperature, that is, temperature detection sensitivity can be adjusted.

  In addition, this invention is not limited to this embodiment, A various deformation | transformation implementation is possible within the range of the summary of this invention.

  For example, in the second embodiment, the switch 115 and the switch 126 may be modified so as to select one resistor from more resistors having different temperature coefficients. In this way, the inclination of the output code DCAL [5: 0] with respect to the temperature can be adjusted more finely.

  The present invention includes configurations that are substantially the same as the configurations described in the embodiments (for example, configurations that have the same functions, methods, and results, or configurations that have the same objects and effects). In addition, the invention includes a configuration in which a non-essential part of the configuration described in the embodiment is replaced. In addition, the present invention includes a configuration that exhibits the same operational effects as the configuration described in the embodiment or a configuration that can achieve the same object. Further, the invention includes a configuration in which a known technique is added to the configuration described in the embodiment.

DESCRIPTION OF SYMBOLS 1 Temperature detection circuit, 10 Resistance part, 12, 13 Resistance, 15 1st switch, 16 2nd switch, 20 Voltage selection part, 22 Selection voltage, 30 Voltage comparison part, 32 Comparison result, 34 Reference voltage, 40 Temperature Information code generation unit, 42 digital code, 44 selection signal, 50 temperature information code correction unit, 52 digital code, 54 correction bit information, 110 bit adjustment circuit, 112-1 to 112-15 resistor, 113 resistor, 114-1 to 114-15 switch, 115 switch, 116 decoder, 120-0 to 120-63 resistor, 122,124 resistor, 126 switch, 200 multiplexer, 300 comparator, 310 reference voltage generation circuit, 312, 314 resistor, 400 successive approximation Circuit, 500 digital adjustment circuit

Claims (5)

A resistance unit in which a plurality of resistors including at least two types of resistors having different temperature characteristics of resistance values are connected in series between two power sources;
A voltage selection unit that receives voltages at a plurality of connection points of the resistance unit and selects one voltage from the voltages at the plurality of connection points according to a selection signal;
A voltage comparison unit that compares a voltage selected by the voltage selection unit with a constant reference voltage;
According to the comparison result of the voltage comparison unit, the selection signal is sequentially changed so that the voltage selected by the voltage selection unit approaches the reference voltage, and a digital code representing temperature information based on the selection signal is provided. A temperature detection circuit including a temperature information code generation unit to be generated. In claim 1,
The resistance portion is
At least one of the plurality of resistors is a resistor having a positive temperature characteristic in which a resistance value increases as the temperature increases, and at least one of the plurality of resistors is a negative resistor whose resistance value decreases as the temperature increases. A temperature detection circuit that is a resistor having temperature characteristics. In claim 1 or 2,
The resistance portion is
A temperature detection circuit including a first switch for bypassing at least one of the plurality of resistors. In any one of Claims 1 thru | or 3,
The resistance portion is
Unlike with any of said plurality of resistors, and other and resistance-temperature characteristics are different at least one resistor and the resistance value of said plurality of resistors, for switching said at least one resistor to the other resistor including a second switch, a temperature detection circuit. In any one of Claims 1 thru | or 4,
A temperature detection circuit further comprising a temperature information code correction unit that corrects the digital code generated by the temperature information code generation unit based on correction bit information.

Images