CN110132444B - Temperature detection circuit - Google Patents
Temperature detection circuit Download PDFInfo
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- CN110132444B CN110132444B CN201810129269.8A CN201810129269A CN110132444B CN 110132444 B CN110132444 B CN 110132444B CN 201810129269 A CN201810129269 A CN 201810129269A CN 110132444 B CN110132444 B CN 110132444B
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01K—MEASURING TEMPERATURE; MEASURING QUANTITY OF HEAT; THERMALLY-SENSITIVE ELEMENTS NOT OTHERWISE PROVIDED FOR
- G01K7/00—Measuring temperature based on the use of electric or magnetic elements directly sensitive to heat ; Power supply therefor, e.g. using thermoelectric elements
- G01K7/16—Measuring temperature based on the use of electric or magnetic elements directly sensitive to heat ; Power supply therefor, e.g. using thermoelectric elements using resistive elements
- G01K7/22—Measuring temperature based on the use of electric or magnetic elements directly sensitive to heat ; Power supply therefor, e.g. using thermoelectric elements using resistive elements the element being a non-linear resistance, e.g. thermistor
Abstract
The invention provides a temperature detection circuit, comprising: the device comprises a controllable current source module, a current source adjusting module, a thermistor and an ADC (analog-to-digital converter) module, wherein the controllable current source module is provided with a plurality of current gears, the current of one gear is output under the control of the current source adjusting module, and the current generates a detection voltage signal on the thermistor; the current source adjusting module is used for outputting a control signal according to the detection voltage signal to control the controllable current source module to output the current of one of the current gears, so that the detection voltage signal meets the input range of the ADC module; and the ADC module is used for reversely deducing the temperature according to the detection voltage signal when the detection voltage signal meets the input range. The invention can enlarge the temperature detection range.
Description
Technical Field
The invention relates to the technical field of circuits, in particular to a temperature detection circuit.
Background
In order to ensure the working safety of mobile phone equipment, intelligent terminal equipment or batteries and the like, the temperature of the equipment is detected. At present, the most applied is realized by a resistor voltage division scheme, a specific temperature detection circuit is shown in fig. 1, a pull-up resistor R1 and an NTC (negative temperature coefficient) thermistor are connected in series between a power supply VCC and the ground, and an ADC module can reversely deduce the current temperature according to the voltage VOUT on the NTC thermistor, thereby realizing temperature detection.
In the process of implementing the invention, the inventor finds that at least the following technical problems exist in the prior art:
because the power supply and the pull-up resistor are fixed, when the temperature variation range is large, the resistance value of the thermistor is a wide range, so that the voltage value of the NTC thermistor is also a wide range and possibly exceeds the detection range of the ADC module, and the detectable temperature range of the conventional temperature detection circuit is small.
Disclosure of Invention
The temperature detection circuit provided by the invention can expand the temperature detection range.
The invention provides a temperature detection circuit, comprising: a controllable current source module, a current source adjusting module, a thermistor and an ADC module, wherein,
the controllable current source module is provided with a plurality of current gears and outputs the current of one gear under the control of the current source adjusting module;
one end of the thermistor is grounded, the other end of the thermistor is connected with the output end of the controllable current source module, and a detection voltage signal is generated by using the current output by the controllable current source module;
the current source adjusting module is configured to output a control signal according to the detection voltage signal, where the control signal is used to control the controllable current source module to output a current of one of a plurality of current gears, so that the detection voltage signal satisfies an input range of the ADC module;
and the ADC module is used for reversely deducing the temperature according to the detection voltage signal when the detection voltage signal meets the input range of the ADC module.
Optionally, the controllable current source module includes a plurality of current source branches connected in parallel, different current source branches are used for outputting currents of different gears, an input end of each current source branch is connected to a point to form a first common end, the first common end is connected to the power supply, an output end of each current source branch is connected to a point to form a second common end, and the second common end is connected to the thermistor.
Optionally, one of the current source branches is taken as a reference branch, the output current of the reference branch is taken as a reference current, a part of branches in the rest of the current source branches increases the output current in sequence with the reference current as a reference, and the other part of branches decreases the output current in sequence with the reference current as a reference.
Optionally, the current source branch includes current source and N type MOS pipe, the input of current source with the power is connected, the output of current source with the drain electrode of N type MOS pipe is connected, the grid of N type MOS pipe inserts the control signal that current source adjusting module exported, the source of N type MOS pipe with thermistor is connected.
Optionally, the current source adjusting module includes a first voltage comparator, a second voltage comparator and a logic operation unit, wherein,
the first voltage comparator is configured to compare the detection voltage signal with a first threshold signal, and when the detection voltage signal is smaller than the first threshold signal, the first voltage comparator outputs a high level signal, and when the detection voltage signal is larger than the first threshold signal, the first voltage comparator outputs a low level signal;
the second voltage comparator is configured to compare the detection voltage signal with a second threshold signal, and output a high level signal when the detection voltage signal is greater than the second threshold signal, and output a low level signal when the detection voltage signal is less than the second threshold signal, where the first threshold signal is less than the second threshold signal;
the logic operation unit is configured to generate a control signal including a set of level signals according to the level signal output by the first voltage comparator and the level signal output by the second voltage comparator, where the control signal is used to turn on one of the current source branches.
Optionally, the logic operation unit is further configured to output a control signal including a set of level signals in a default condition, where the control signal is used to turn on the reference branch.
Optionally, the controllable current source module and the current source adjusting module are integrated in one chip.
According to the temperature detection circuit provided by the invention, one branch is selected from the multiple current source branches to be connected, so that the voltage generated by the current source branch on the thermistor meets the input range of the ADC module, and the voltage value on the thermistor can always meet the input range of the ADC module within a very wide temperature range through switching of the current source branches. Furthermore, the voltage value of the thermistor is limited to a most reasonable range, so that the temperature detection precision is high.
Drawings
FIG. 1 is a schematic diagram of a conventional temperature detection circuit;
FIG. 2 is a schematic structural diagram of an embodiment of a temperature detection circuit according to the present invention;
FIG. 3 is a schematic structural diagram of another embodiment of a temperature detection circuit according to the present invention;
FIG. 4 is a schematic diagram of a temperature detection circuit according to another embodiment of the present invention;
fig. 5 is a schematic diagram of the operating principle of the temperature detection circuit of the present invention.
Detailed Description
In order to make the objects, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
An embodiment of the present invention provides a temperature detection circuit, as shown in fig. 2, including: a controllable current source module 21, a current source adjusting module 22, a thermistor 23 and an ADC module 24, wherein,
the controllable current source module 21 is provided with a plurality of current gears, is controlled by the current source adjusting module 22, and outputs the current of one gear under the control of the current source adjusting module 22;
the thermistor 23 adopts a Negative Temperature Coefficient (NTC) thermistor, one end of the thermistor 23 is grounded, the other end is connected with the output end of the controllable current source module 21, and a detection voltage signal VOUT is generated by using the current output by the controllable current source module 21;
the current source regulating module 22 is configured to output a control signal CUR _ SEL according to the detection voltage signal VOUT, where the control signal CUR _ SEL is configured to control the controllable current source module 21 to output a current of one of the multiple current steps, so that the detection voltage signal VOUT meets an input range of the ADC module 24;
the ADC module 24 is configured to inversely derive the temperature according to the detection voltage signal VOUT when the detection voltage signal VOUT satisfies an input range of the ADC module 24.
In practical design, the controllable current source module 21 and the current source adjusting module 22 can be integrated into one chip.
Optionally, the controllable current source module 21 includes a plurality of current source branches connected in parallel, different current source branches are used for outputting currents of different gears, an input end of each current source branch is connected to a point to form a first common end, the first common end is connected to the power supply, an output end of each current source branch is connected to a point to form a second common end, and the second common end is connected to the thermistor.
It is assumed that the controllable current source module 21 can output I0, I0/2, I0/2 under the control of the current source adjusting module 222，I0/23… … and I0X 2, I0X 22,I0*23… …, each gear corresponds to a current source branch, wherein the current source branch with the output current of I0 is taken as a reference branch, i.e. the current with I0 as the default gear is also taken as the reference current, and the currents of the rest gears are increased or decreased according to an exponential function of 2 by taking I0 as the reference.
As shown in fig. 3, taking three current source branches as an example, each current source branch includes a current source and an N-type MOS transistor, an input end of the current source is connected to the power VCC, an output end of the current source is connected to a drain of the N-type MOS transistor, a gate of the N-type MOS transistor is connected to the control signal output by the current source adjusting module 22, and a source of the N-type MOS transistor is connected to the thermistor.
In this embodiment, the current sources included in the three different current source branches output different currents, which are respectively denoted as I0, I0/2, I0 × 2, and I0 are reference currents, the control signal includes three level signals, the N-type MOS transistors included in the three different current source branches are respectively controlled, only one of the three level signals is a high level signal, and the others are low level signals, so that it is ensured that only one current source branch is switched on. By default, the current source branch with the output current I0 is first turned on, i.e. the controllable current source module 21 outputs the reference current I0.
For the same reason, as shown in FIG. 4, five lines of electricity are usedFor example, the current source branches include five current source branches outputting different currents, I0, I0/2, I0/22And I0 x 2, I0 x 22And I0 is reference current, the control signal comprises five level signals which respectively control different current source branches, wherein only one level signal is a high level signal, the branch controlled by the high level signal is ensured to be connected, the rest branches are all disconnected, and the current source branch with the output current of I0 is firstly connected under the default condition.
Further, referring to fig. 3 or fig. 4, the current source adjusting module 22 includes a first voltage comparator U0, a second voltage comparator U1, and a logic operation unit U2, wherein,
the first voltage comparator U0 is used for comparing the detection voltage signal VOUT with a first threshold signal, the + input end of the U0 is connected with the first threshold signal, the-input end of the U0 is connected with the detection voltage signal VOUT, when the detection voltage signal is smaller than the first threshold signal, the output signal S0 of the U0 is at a high level, and when the detection voltage signal is larger than the first threshold signal, the output signal S0 of the U0 is at a low level;
the second voltage comparator U1 is used for comparing the detection voltage signal VOUT with a second threshold signal, the + input end of the U1 is connected with the detection voltage signal, the-input end of the U1 is connected with the second threshold signal, when the detection voltage signal is greater than the second threshold signal, the output signal S1 of the U1 is a high level signal, and when the detection voltage signal is less than the second threshold signal, the output signal S1 of the U1 is a low level signal;
and the logic operation unit U2 is configured to generate a control signal including a set of level signals according to the level signal S0 output by the first voltage comparator U0 and the level signal S1 output by the second voltage comparator U1, wherein different level signals in the control signal respectively control different current source branches, only one of the control signal is a high level signal, and one of the current source branches is switched on. In a default situation, the control signal output by the logic unit U2 first turns on the current source branch with the output current I0, and then determines whether to switch the current source branch according to the detection voltage signal VOUT.
In this embodiment, the first threshold signal is 0.2V, and the second threshold signal is 1.2V, which are designed according to the input range of the ADC module, so that 0.2V to 1.2V are the input range of the ADC module.
According to the temperature detection circuit provided by the embodiment of the invention, one of the multiple current source branches is selected to be connected, so that the voltage generated by the current source branch on the thermistor meets the input range of the ADC module, and the voltage value on the thermistor can always meet the input range of the ADC module within a very wide temperature range through switching of the current source branches. Furthermore, the voltage value of the thermistor is limited to a most reasonable range, so that the temperature detection precision is high. According to the scheme, the resolution ratio of temperature detection at high and low temperatures is very high (more than 8mV), and the accuracy of temperature detection at high and low temperatures is very accurate (less than 1.5 ℃).
In addition, the invention can be applied to temperature detection of mobile phone communication equipment, and also can be applied to temperature detection in other intelligent terminal equipment fields by properly modifying technical parameters, thereby realizing temperature detection of mobile phone equipment, intelligent terminal equipment and batteries in a wider temperature range from low temperature to high temperature.
The operation principle of the temperature detection circuit in the above embodiment is shown in fig. 5:
the current source adjusting module 22 is connected with a current source branch with an output current of I0 under the default condition, and when detecting that a detection voltage signal generated by I0 on the thermistor is in the range of [0.2,1.2], the current source branch does not need to be switched;
when the detection voltage signal generated by the thermistor by I0 is detected<At 0.2V, the current source adjusting module 22 sends out a control signal to switch the controllable current source module 21 to I0 × 2, I0 × 2 in turn2,I0*23.., until satisfied>0.2V；
When the detection voltage signal generated on the I0 thermistor is detected>At 1.2V, the current source adjusting module 22 sends out a control signalThe controllable current source module 21 is switched to I0/2 and I0/2 in turn2，I0/23.. until satisfied<1.2V。
Specifically, for example, an NTC thermistor with a standard resistance of 10K at 25 ℃ has a temperature R of-20 DEG CNTCIf the default gear I0 is 40uA, then V is 68.23KNTC＝40uA*68.23K＝2.7V>1.2V, and reducing the first gear to 20uA, VNTC＝20uA*68.23K＝1.35V>1.2V, and then reducing the first gear to 10uA, VNTC10uA 68.23K 0.682V, [0.2,1.2]And the interval range meets the input range of the ADC module. And according to the resistance characteristic of 10KNTC, a 10uA current source is used in the range of-30 ℃ to 8 ℃, the requirement of the range can be met, and the detection of the temperature range is realized.
The temperature detection circuit can ensure that the detection voltage signal always meets the input range of the ADC module in the whole temperature detection range by switching the current source branch circuits, and meets the detection requirements of different temperatures, thereby expanding the temperature detection range.
The above description is only for the specific embodiment of the present invention, but the scope of the present invention is not limited thereto, and any changes or substitutions that can be easily conceived by those skilled in the art within the technical scope of the present invention are included in the scope of the present invention. Therefore, the protection scope of the present invention shall be subject to the protection scope of the claims.
Claims (7)
1. A temperature sensing circuit, comprising: a controllable current source module, a current source adjusting module, a thermistor and an ADC module, wherein,
the controllable current source module comprises a plurality of parallel current source branches, and each current source branch is used for outputting current of different gears;
one end of the thermistor is grounded, the other end of the thermistor is connected with the output end of the controllable current source module, and a detection voltage signal is generated by using the current output by the controllable current source module;
the current source adjusting module is configured to output a control signal according to the detection voltage signal, where the control signal is used to control the controllable current source module to select a current of one of multiple current gears for output, so as to adjust the detection voltage signal to make the detection voltage signal meet an input range of the ADC module;
and the ADC module is used for reversely deducing the temperature according to the detection voltage signal when the detection voltage signal meets the input range of the ADC module.
2. The temperature detecting circuit according to claim 1, wherein the input terminals of the current source branches of the controllable current source module are connected to a point to form a first common terminal, the first common terminal is connected to a power source, the output terminals of the current source branches are connected to a point to form a second common terminal, and the second common terminal is connected to the thermistor.
3. The temperature detection circuit according to claim 2, wherein one of the plurality of current source branches is a reference branch, an output current of the reference branch is a reference current, a part of the remaining current source branches increases the output current in sequence with reference to the reference current, and another part of the remaining current source branches decreases the output current in sequence with reference to the reference current.
4. The temperature detection circuit according to claim 3, wherein the current source branch comprises a current source and an N-type MOS transistor, an input end of the current source is connected to the power supply, an output end of the current source is connected to a drain of the N-type MOS transistor, a gate of the N-type MOS transistor is connected to the control signal output by the current source regulation module, and a source of the N-type MOS transistor is connected to the thermistor.
5. The temperature detection circuit of claim 4, wherein the current source adjustment module comprises a first voltage comparator, a second voltage comparator, and a logic operation unit,
the first voltage comparator is configured to compare the detection voltage signal with a first threshold signal, and when the detection voltage signal is smaller than the first threshold signal, the first voltage comparator outputs a high level signal, and when the detection voltage signal is larger than the first threshold signal, the first voltage comparator outputs a low level signal;
the second voltage comparator is configured to compare the detection voltage signal with a second threshold signal, and output a high level signal when the detection voltage signal is greater than the second threshold signal, and output a low level signal when the detection voltage signal is less than the second threshold signal, where the first threshold signal is less than the second threshold signal;
the logic operation unit is configured to generate a control signal including a set of level signals according to the level signal output by the first voltage comparator and the level signal output by the second voltage comparator, where the control signal is used to turn on one of the current source branches.
6. The temperature detection circuit according to claim 5,
the logic operation unit is further configured to output a control signal including a set of level signals under a default condition, and the control signal is used to turn on the reference branch.
7. The temperature sensing circuit of claim 1, wherein the controllable current source module and the current source regulation module are integrated in a single chip.
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| CN113218527B (en) * | 2021-05-12 | 2023-01-31 | 展讯通信（上海）有限公司 | Thermistor-based temperature detection method, device, equipment, medium and system |
| CN114028657A (en) * | 2021-11-16 | 2022-02-11 | 全鼎电子(苏州)有限公司 | Infusion heating control technology |
| CN117232678A (en) * | 2022-06-06 | 2023-12-15 | 深圳英集芯科技股份有限公司 | Temperature detection circuit, related chip and related charging device |
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