阅读说明：本技术 多段式温度检测电路及温度检测方法 (Multi-section temperature detection circuit and temperature detection method ) 是由 张吉儒 叶兆屏 于 2020-12-02 设计创作，主要内容包括：本发明涉及温度检测技术领域,具体来说是一种多段式温度检测电路及温度检测方法,包括至少两个调控单元,一个比较单元和一个分压电阻串单元,比较单元包括两个比较器,两个比较器的正相输入端分别连接至分压电阻串单元中以获取分压电压值,两个比较器的反相输入端分别连接两个调控单元,调控单元用于调整两个比较器的正向输入端的电压值。本发明可以减少热敏电阻器RTC和比较器的使用,仅使用一个热敏电阻器RTC和两个比较器,降低了应用成本、减小了PCB面积、减少了采集芯片的引脚数量并降低了应用电路的复杂度；引入N个开关和N个栅端控制信号,并将栅端控制信号同时作为开关的通断控制信号,通过控制采集周期就能降采集电路的功耗,实现低功耗。(The invention relates to the technical field of temperature detection, in particular to a multi-section temperature detection circuit and a temperature detection method. The invention can reduce the use of the RTC and the comparator, only uses one RTC and two comparators, reduces the application cost, reduces the PCB area, reduces the pin number of the acquisition chip and reduces the complexity of the application circuit; n switches and N grid end control signals are introduced, the grid end control signals are simultaneously used as on-off control signals of the switches, the power consumption of the acquisition circuit can be reduced by controlling the acquisition period, and low power consumption is achieved.)

1. The utility model provides a multistage formula temperature detect circuit which characterized in that, includes two at least regulation and control units, a comparing element and a divider resistance string unit, the comparing element include two comparators, the normal phase input of two comparators be connected to the divider resistance string respectively and in order to obtain the partial pressure voltage value, the inverting input of two comparators connect two regulation and control units respectively, regulation and control unit be used for adjusting the voltage value of the positive input of two comparators, divider resistance string unit including two at least divider resistance of series connection for provide the voltage value for the normal phase input of comparator.

2. The multi-stage temperature sensing circuit of claim 1,

each regulating unit comprises an NMOS (N-channel metal oxide semiconductor) tube, a NOT gate and a PMOS (P-channel metal oxide semiconductor) tube, wherein the gate end of the NMOS tube is connected with a gate end control signal and the input end of the NOT gate, the source end of the NMOS tube is connected with the drain end of the PMOS tube and a peripheral circuit, and the gate end of the PMOS tube is connected with the output end of the NOT gate;

the comparison unit comprises a comparator 1 and a comparator 2, wherein the inverting input end of the comparator 1 is connected with a switch in series and then is connected to the front end of any one divider resistor, the inverting input end of the comparator 2 is connected with at least one switch, and the at least one switch is respectively connected to the front ends of the rest divider resistors; the number of the voltage dividing resistors and the total number of the switches correspond to the number of the regulating units;

and the drain terminals of the NMOS transistors of all the control units are connected to the VCC terminal, the source terminals of the PMOS transistors of all the control units are connected to one end of the voltage dividing resistor string, the drain terminal of any one PMOS transistor is connected to the inverted input terminal VT1 of the comparator 1, and the drain terminal of any other PMOS transistor is connected to the inverted input terminal VT2 of the comparator 2.

3. The multi-stage temperature detecting circuit according to claim 2, wherein only one thermistor RTC is provided in the peripheral circuit.

4. The multi-stage temperature detecting circuit according to claim 3, wherein the peripheral circuit further includes at least two peripheral resistors corresponding to the control units, one end of each of the at least two peripheral resistors is connected to the same end of the thermistor RTC, and the other ends of the at least two peripheral resistors are respectively connected to the corresponding control units.

5. The multi-stage temperature detecting circuit according to claim 2, wherein the source terminal lead-out pin of the NMOS transistor serves as the connection terminal of the peripheral circuit.

6. The multi-stage temperature sensing circuit of claim 5,

the power supply circuit comprises N NMOS tubes, wherein N is a natural number which is more than or equal to 2, gate ends of N NMOS tubes NM1-NMN are respectively connected with gate end control signals phi 1-phi N and are respectively connected with input ends of NAND gates 1-NOT gates N, drain ends of N NMOS tubes NM1-NMN are connected to a power supply VCC end in parallel, source ends of N NMOS tubes NM1-NMN are respectively connected with drain ends of N PMOS tubes PM1-PMN and are connected to chip pins PT1-PTN, gate ends of N PMOS tubes PM1-PMN are respectively connected with output ends of NOT gates 1-NOT gates N, source ends of N PMOS tubes PM1-PMN are connected to one end of a resistor RFN in parallel, the other end of the RFN is connected with other RF resistors in series, the last RF resistor is grounded, and drain ends of N PMOS tubes PM1-PMN are respectively connected with source ends of N NMOS tubes 1-NMN and are connected to chip pins PT 1-PTN;

the positive phase input end of the comparator 1 is connected to the switch S1 and then connected to the front end of the resistor RF1, the negative phase input end of the comparator 1 is connected to the chip pin PT2, the positive phase input end of the comparator 2 is connected to the resistors RF2-RFN after being connected with the switches S2-SN connected in parallel, and the negative phase input end of the comparator 2 is connected to the chip pin PT 1.

7. The multi-stage temperature detecting circuit according to claim 1, wherein the at least two regulating units, the comparing unit and the voltage dividing resistor string unit are integrated in an integrated circuit.

8. A temperature detecting method using the multi-stage temperature detecting circuit according to claim 1, wherein the operating signals are sequentially inputted to the at least two control units to perform multi-stage temperature detection.

9. A temperature detecting method using the multi-stage temperature detecting circuit according to claim 2, wherein the operating signals are sequentially inputted to the at least two regulating units to perform multi-stage temperature detection, and the gate control signal is simultaneously used as an on-off control signal of the switch corresponding to the regulating unit, when the gate control signal of any regulating unit is at a high level, the switch corresponding to any regulating unit is turned on, the gate control signals of the other regulating units are at a low level, and the switches corresponding to the other regulating units are turned off.

10. The temperature detecting method of the multi-stage temperature detecting circuit according to claim 8 or 9, wherein the resistance value of the thermistor RTC when the regulating unit connected to the comparator 2 operates is obtained according to the following formula:

wherein VT1 is the voltage value of the inverting input terminal of the comparator 1, VR1 is the voltage value of the non-inverting input terminal of the comparator 1, R1 is the resistance value of the peripheral resistor corresponding to the regulation and control unit connected to the comparator 2, and V1 is the voltage value of the source terminal of the NMOS transistor of the regulation and control unit connected to the comparator 2;

the resistance value of the thermistor RTC when any other regulating and controlling unit works is obtained according to the following formula:

wherein VT2 is the voltage value of the inverting input terminal of the comparator 2, VRi is the voltage value of the non-inverting input terminal of the comparator 2, Ri is the resistance value of the peripheral resistor corresponding to any of the other regulating units, and Vi is the voltage value of the source terminal of the NMOS transistor of any of the other regulating units.

Technical Field

The invention relates to the technical field of temperature detection, in particular to a multi-section temperature detection circuit and a temperature detection method.

Background

Temperature sensing circuits are an important component of some electronic systems. In practical application, the temperature detection technology can detect the temperature of a PCB, the temperature of a battery, the temperature of electronic components, a chip and the like. In the technologies such as sensor and internet of things application, the temperature detection technology is also an important component.

A thermistor is a temperature-sensitive electronic component that exhibits different resistance values at different temperatures. The thermistors are classified into a positive temperature coefficient thermistor (PTC) having a higher resistance value at a higher temperature and a negative temperature coefficient thermistor (NTC) having a lower resistance value at a higher temperature, according to the temperature coefficient. Since the resistance value of the thermistor changes depending on the temperature, it can be used for a temperature detection circuit.

Usually, the temperature detection circuit is integrated into a chip, a chip pin is externally connected with a thermistor RTC, and the temperature of the measured point is detected by using the characteristic that the resistance of the thermistor RTC changes with the temperature. Under different application scenes, the adaptive requirements on the temperature range are different, and the temperature to be detected is higher or lower. Once a peripheral device is determined, the traditional temperature detection technology can only detect a single temperature point, and cannot carry out temperature adjustment and temperature detection according to practical application scenes, and the multi-section temperature detection circuit can detect the temperature of a detected point, can detect a more specific temperature range, and carries out temperature protection, temperature compensation and the like on the detected point.

The existing multi-section temperature detection circuit is shown in fig. 1, and a dotted line frame is an internal circuit of a chip, which includes 2 comparators, a comparator 1 and a comparator 2; 3 resistors, resistor RF1, resistor RF2 and resistor RF 3; the periphery of the chip is provided with 2 resistors, namely a resistor R1 and a resistor R2; 2 thermistors, thermistor RTC1 and thermistor RTC 2.

Specifically, the positive phase input end of the comparator 1 is connected with one end of a resistor RF1, and the positive phase input voltage is VR 1; the inverting input of comparator 1 is connected to chip pin PT 3; the output voltage of the comparator 1 is VO 1. The positive phase input end of the comparator 2 is connected with one end of a resistor RF3, and the positive phase input voltage is VR 2; the inverting input of comparator 2 is connected to chip pin PT 2; the output voltage of the comparator 2 is VO 2. The three resistors RF1, RF2 and RF3 inside the chip are connected in series in sequence, one end of the series is connected with voltage VR, and the other end is grounded. A resistor R1 of the chip peripheral resistor is connected in series with a thermistor RTC1 to a chip pin PT1, wherein one end of the thermistor RTC1 is connected with a pin PT 3; the resistor R2 and the thermistor RTC2 are connected in series to a chip pin PT1, wherein one end of the thermistor RTC2 is connected to a pin PT 2.

The working process of the multi-section temperature detection circuit is as follows: according to the principle of series resistance voltage division, voltage VR is divided by series resistance, and the voltage value of voltage VR1 is obtained as follows:

note: the voltage VR1 has a value equal to the sum of the resistances of the resistors RF1, RF1, RF2, and RF3 multiplied by the voltage VR. The voltage at the non-inverting input of comparator 1 is VR 1.

The voltage value of the inverting input terminal voltage VT1 of the comparator 1 is:

note: the voltage VT1 has a voltage value equal to the thermistor R_RTC1Is divided by the thermistor R_RTC1Is compared with the resistance of the resistor R1 and multiplied by the voltage VR.

When the voltage VT1 at the inverting input end of the comparator 1 is larger than the voltage VR1 at the non-inverting input end of the comparator 1, starting the temperature protection circuit; when the inverting input terminal voltage VT1 of the comparator 1 is smaller than the non-inverting input terminal voltage VR1 of the comparator 1, the temperature protection circuit cannot be started without reaching the temperature point at which the temperature protection circuit is started.

When the temperature protection circuit is started, the inverting input voltage VT1 of the comparator 1 is made equal to the non-inverting input voltage VR1 of the comparator 1, that is:

the VR1 voltage value is obtained by proportionally and serially connecting resistors inside the chip for voltage division, the resistance value of the peripheral resistor R1 can be set and adjusted, and the VR voltage value is set to be known.

Under the condition that the VR1 voltage, the VR voltage and the resistance of the peripheral resistor R1 are known, the resistance R of the thermistor RTC1 can be obtained according to the formula (3)_RTC1Then, according to the relationship between the resistance and the temperature of the thermistor RTC1, the temperature point of the corresponding thermistor RTC1 at that time, i.e. the first collected temperature point, can be obtained.

According to the principle of series resistance voltage division, voltage VR is divided by series resistance, and the voltage value of voltage VR2 is obtained as follows:

note: the voltage VR2 is equal to the sum of the resistances of the resistors RF1 and RF2 divided by the sum of the resistances of the resistors RF1, RF2 and RF3 multiplied by the voltage VR.

At this time, the voltage value of the non-inverting input terminal voltage of the comparator 2 is VR2, and the voltage value of the inverting input terminal voltage VT2 of the comparator 2 is:

note: the voltage VT2 has a voltage value equal to the thermistor R_RTC2Is divided by the thermistor R_RTC2Is compared with the resistance of the resistor R2 and multiplied by the voltage VR.

When the inverting input terminal voltage VT2 of the comparator 2 is larger than the non-inverting input terminal voltage VR2 of the comparator 2, starting the temperature protection circuit; when the inverting input terminal voltage VT2 of the comparator 2 is smaller than the non-inverting input terminal voltage VR2 of the comparator 2, the temperature protection circuit cannot be started without reaching the temperature point at which the temperature protection circuit is started.

When the temperature protection circuit is activated, the inverting input voltage VT2 of the comparator 2 is made equal to the non-inverting input voltage VR2 of the comparator 2, that is:

the VR2 voltage value is obtained by proportionally and serially connecting resistors inside the chip for voltage division, the resistance value of the peripheral resistor R2 can be set and adjusted, and the VR voltage value is set to be known.

Under the condition that the VR2 voltage, the VR voltage and the resistance of the peripheral resistor R2 are known, the resistance R of the thermistor RTC2 can be obtained according to the formula (6)_RTC2Then, according to the relationship between the resistance and the temperature of the thermistor RTC2, the temperature point of the corresponding thermistor RTC2 at that time, i.e. the second collected temperature point, can be obtained.

Based on the principle and the like, the working process of the conventional multi-section temperature detection circuit is described by taking two temperature points as an example, and based on the principle, the acquisition of N temperature points can be realized by using N peripheral resistors R1-Ri, i is more than or equal to 2 and less than or equal to N, N thermistors RTC1-RTCi, i is more than or equal to 2 and less than or equal to N, and N comparators 1-i, i is more than or equal to 2 and less than or equal to N. Wherein, i represents the number of the device, N represents the number of the device, which are all natural numbers, and the value ranges are that i is more than or equal to 2 and less than or equal to N.

Therefore, the current circuit for realizing multi-section temperature detection needs a plurality of thermistors RTCs and a plurality of comparators to acquire a plurality of temperature points, which causes the problems of high cost, high power consumption and large occupied area.

Disclosure of Invention

The invention aims to solve the problem that a plurality of thermistors RTC and a plurality of comparators are required to be arranged when a plurality of temperature points are collected by the conventional multi-stage temperature detection circuit, and provides a multi-stage temperature detection circuit and a temperature detection method.

In order to achieve the above object, a multi-stage temperature detection circuit is designed, which includes a comparison unit, a voltage dividing resistor string unit and at least two control units, wherein the comparison unit includes only two comparators, positive phase input terminals of the two comparators are connected to the voltage dividing resistor string respectively to obtain a divided voltage value, negative phase input terminals of the two comparators are connected to the two control units respectively, the control units are used for adjusting voltage values of positive phase input terminals of the two comparators according to a gate terminal control signal, and the voltage dividing resistor string unit includes at least two voltage dividing resistors connected in series and used for providing a voltage value for the positive phase input terminals of the comparators.

Preferably, each of the regulation units respectively comprises an NMOS transistor, a not gate and a PMOS transistor, wherein a gate terminal of the NMOS transistor is connected to a gate terminal control signal and an input terminal of the not gate, a source terminal of the NMOS transistor is connected to a drain terminal of the PMOS transistor and a peripheral circuit, and a gate terminal of the PMOS transistor is connected to an output terminal of the not gate; the comparison unit comprises a comparator 1 and a comparator 2, wherein the inverting input end of the comparator 1 is connected with a switch in series and then is connected to the front end of any one divider resistor, the inverting input end of the comparator 2 is connected with at least one switch, and the at least one switch is respectively connected to the front ends of the rest divider resistors; the voltage dividing resistor string unit comprises at least two voltage dividing resistors which are connected in series, one end of each resistor which is connected in series is grounded GND, the other end of each resistor is connected with voltage VR, and the number of the voltage dividing resistors and the total number of the switches correspond to the number of the regulating units; and the drain terminals of the NMOS transistors of all the control units are connected to the VCC terminal, the source terminals of the PMOS transistors of all the control units are connected to one end of the voltage dividing resistor string, the drain terminal of any one PMOS transistor is connected to the inverted input terminal VT1 of the comparator 1, and the drain terminal of any other PMOS transistor is connected to the inverted input terminal VT2 of the comparator 2.

Preferably, in said peripheral circuit, only one thermistor RTC is provided.

Preferably, the peripheral circuit further includes at least two peripheral resistors corresponding to the control unit, one end of each of the at least two peripheral resistors is connected to the same end of the thermistor RTC, and the other ends of the at least two peripheral resistors are respectively connected to the corresponding control units.

Preferably, a pin led out from a source end of the NMOS transistor is used as a connection end of the peripheral circuit.

Preferably, the multi-stage temperature detection circuit comprises N NMOS tubes, N is a natural number greater than or equal to 2, the grid ends of the N NMOS tubes NM1-NMN are respectively connected with grid end control signals phi 1-phi N, and the input ends of the NAND gates 1-the NOT gates N are connected respectively, the drain ends of the N NMOS tubes NM1-NMN are connected in parallel to a power supply VCC end, the source ends of the N NMOS tubes NM1-NMN are connected with the drain ends of the N PMOS tubes PM1-PMN respectively and connected to a chip pin PT1-PTN, the gate ends of the N PMOS tubes PM1-PMN are connected with the output ends of the NOT gates 1-the NOT gates N respectively, the source ends of the N PMOS tubes PM1-PMN are connected in parallel to one end of a resistor RFN, the other end of the RFN is connected in series with other RF resistors, the last RF resistor is grounded, and the drain terminals of the N PMOS tubes PM1-PMN are respectively connected with the source terminals of the N NMOS tubes NM1-NMN to chip pins PT 1-PTN; the positive phase input end of the comparator 1 is connected to the switch S1 and then connected to the front end of the resistor RF1, the negative phase input end of the comparator 1 is connected to the chip pin PT2, the positive phase input end of the comparator 2 is connected to the resistors RF2-RFN after being connected with the switches S2 ᄀ -SN connected in parallel, and the negative phase input end of the comparator 2 is connected to the chip pin PT 1.

Preferably, the at least two regulating units, one comparing unit and one voltage dividing resistor string unit are integrated in an integrated circuit.

The invention also relates to a temperature detection method adopting the multi-section temperature detection circuit, which inputs working signals to the at least two regulating units in sequence to carry out multi-section temperature detection.

Preferably, the temperature detection method uses the gate terminal control signal as an on-off control signal of a switch corresponding to the regulation and control unit, when the gate terminal control signal of any regulation and control unit is at a high level, the switch corresponding to any regulation and control unit is turned on, the gate terminal control signals of the other regulation and control units are at a low level, and the switches corresponding to the other regulation and control units are turned off.

Preferably, the temperature detection method obtains the resistance value of the thermistor RTC when the regulation and control unit connected to the comparator 2 works according to the following formula:

wherein VT1 is the voltage value of the inverting input terminal of the comparator 1, VR1 is the voltage value of the non-inverting input terminal of the comparator 1, R1 is the resistance value of the peripheral resistor corresponding to the regulation and control unit connected to the comparator 2, and V1 is the voltage value of the source terminal of the NMOS transistor of the regulation and control unit connected to the comparator 2;

and the resistance value of the thermistor RTC when any other regulating and controlling unit works is obtained according to the following formula:

wherein VT2 is the voltage value of the inverting input terminal of the comparator 2, VRi is the voltage value of the non-inverting input terminal of the comparator 2, Ri is the resistance value of the peripheral resistor corresponding to any of the other regulating units, and Vi is the voltage value of the source terminal of the NMOS transistor of any of the other regulating units.

Compared with the prior art, the invention has the advantages that: the use of a thermistor RTC and a comparator can be reduced, and the acquisition of N temperature points can be realized according to the characteristic that the resistance of the thermistor RTC changes along with the temperature by only using one thermistor RTC and two comparators, so that the application cost is effectively reduced, the PCB area is reduced, the pin number of an acquisition chip is reduced, and the complexity of an application circuit is reduced; n switches and N grid end control signals are introduced, the grid end control signals are simultaneously used as on-off control signals of the switches to control the on-off of the multi-section temperature detection circuit, the power consumption of the acquisition circuit can be effectively reduced and optimized by controlling the acquisition period, and the low-power-consumption design is realized; meanwhile, the temperature detection circuit is convenient to integrate into an integrated chip, for example, an SoC chip, and only one thermistor RTC and a corresponding peripheral resistor need to be connected through a pin of the integrated chip, so that the structure of the peripheral circuit is simplified, the integration level of the high-temperature detection circuit is improved, and the occupied area is reduced.

Drawings

Fig. 1 is a schematic diagram of a multi-stage temperature detection circuit in the prior art.

FIG. 2 is a schematic diagram of a multi-stage temperature detecting circuit according to the present invention.

FIG. 3 is a diagram of a gate control signal of the multi-stage temperature detection circuit according to the present invention.

Detailed Description

The structure and principles of such circuits and methods will be apparent to those skilled in the art from the following further description of the invention taken in conjunction with the accompanying drawings. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.

This embodiment provides a multistage formula temperature detect circuit, including a comparing element, a divider resistance string unit and two at least regulation and control units, comparing element include two comparators only, the normal phase input of two comparators be connected to divider resistance string respectively in order to obtain the partial pressure voltage value, the inverting input of two comparators connect two regulation and control units respectively, regulation and control unit be used for according to the voltage value of the positive input of grid end control signal adjustment two comparators, divider resistance string unit provide the voltage value for the normal phase input of comparator.

Specifically, each regulating and controlling unit respectively comprises an NMOS (N-channel metal oxide semiconductor) tube, a NOT (not-gate) and a PMOS (P-channel metal oxide semiconductor) tube, the gate end of the NMOS tube is connected with a gate end control signal and the input end of the NOT, the source end of the NMOS tube is connected with the drain end and the peripheral circuit of the PMOS tube, and the gate end of the PMOS tube is connected with the output end of the NOT.

The comparison unit comprises a comparator 1 and a comparator 2, wherein the inverting input end of the comparator 1 is connected with one switch in series and then is connected to the front end of any one divider resistor, the inverting input end of the comparator 2 is connected with at least one switch, the at least one switch is respectively connected to the front ends of the rest divider resistors, and the number of the divider resistors and the total number of the switches correspond to the number of the regulation units.

The voltage dividing resistor string unit comprises at least two voltage dividing resistors which are connected in series, one end of each resistor which is connected in series is grounded GND, and the other end of each resistor is connected with voltage VR, namely the source end of the PMOS tube of the control unit.

And the drain terminals of the NMOS transistors of all the control units are commonly connected to a VCC terminal, the source terminals of the PMOS transistors of all the control units are commonly connected to one end of the voltage dividing resistor string, the drain terminal of any one PMOS transistor is connected to the inverting input terminal VT1 of the comparator 1, and the drain terminal of any other PMOS transistor is connected to the inverting input terminal VT2 of the comparator 2.

When the temperature sensor is used, high-level grid end control signals are sequentially input to the regulating and controlling unit to serve as working signals to switch paths for collecting temperature points, and multi-section temperature detection can be carried out.

The circuit and the method are further illustrated in the following figures and embodiments.

Example 1

As shown in fig. 2, in this embodiment, the multi-stage temperature detection circuit includes an internal circuit and a peripheral circuit, the internal circuit is integrated in an integrated circuit of the control chip, and the internal circuit includes N NMOS transistors: NM1-NMN, N PMOS tubes: PM1-PMN, N NOT gates: not gate 1-not gate N, N RF resistors connected in series in sequence: RF1-RFN, 2 comparators: a comparator 1 and a comparator 2, wherein N is a natural number greater than or equal to 2; the peripheral circuit comprises resistors R1-RN and a thermistor RTC, and the threshold value of each temperature point can be adjusted by independently adjusting the resistance value of the series-connected divider resistors.

Specifically, the gate ends of N NMOS transistors NM1-NMN are respectively connected to gate end control signals Φ 1- Φ N, and are respectively connected to the input ends of nand gate 1-not gate N; the drain terminals of the N NMOS tubes NM1-NMN are connected to a power supply VCC terminal in parallel; the source ends of the N NMOS transistors NM1-NMN are respectively connected with the drain ends of the N PMOS transistors PM1-PMN and connected to chip pins PT 1-PTN. The grid ends of N PMOS pipes PM1-PMN are respectively connected with the output ends of the NOT gate 1-NOT gate N; the source ends of the N PMOS tubes PM1-PMN are connected to one end of a resistor RFN in parallel, the other end of the resistor RFN is connected with the rest RF resistors in series, and the last RF resistor RF1 is grounded; the drain terminals of the N PMOS tubes PM1-PMN are respectively connected with the source terminals of the N NMOS tubes NM1-NMN to chip pins PT 1-PTN.

The positive phase input end of the comparator 1 is connected to the switch S1 and then connected to the front end of the resistor RF1, so that the voltage at the positive phase input end of the comparator 1 is VR1, the negative phase input end of the comparator 1 is connected to the chip pin PT2, and the output voltage at the output end of the comparator 1 is V01.

The positive phase input end of the comparator 2 is connected with the parallel switch S2-SN and then is respectively connected to the resistors RF2-RFN, so that the voltages of the positive phase input end are VR2-VRN respectively, the negative phase input end of the comparator 2 is connected to a chip pin PT1, and the output voltage of the output end of the comparator 2 is V02.

In addition, one end of a resistor R1-Ri of the peripheral circuit is respectively connected with a chip pin PT1-PTi, the other end of the resistor R1-Ri is connected with one end of a thermistor RTC in parallel, and the other end of the thermistor RTC is grounded GND.

Example 2

Referring to fig. 2 and 3, VCC provides power for the chip, and the specific working process of the multi-stage temperature detection circuit of this embodiment is as follows:

when the gate control signal Φ 1 is at a high level, the gate control signals Φ i except Φ 1 are at a low level, the NMOS transistor NM1 is turned on, the gate control signal Φ 1 at the high level is changed to a low level through the not gate 1, so that the PMOS transistor PM1 is turned on, and the gate control signal Φ 1 serves as an on-off control signal of the switch S1, and when the gate control signal Φ 1 is at a high level, the switch S1 is turned on. The source terminal voltage of the NMOS transistor NM1 is a voltage value obtained by lowering the high level of the gate terminal control signal Φ 1 by one threshold voltage, i.e., a voltage V1, and is equal to the source-drain voltage of the PMOS transistor PM1, i.e., VR is equal to V1. After the voltage VR passes through the resistor network, according to the principle of voltage division by the series resistors, the voltage value at the positive phase input end of the comparator 1 is obtained as follows:

namely: the voltage VR1 has a value equal to the sum of the resistances of the resistors RF1 divided by the resistances of the resistors RF1-RFi multiplied by the voltage VR.

Meanwhile, when the gate control signal Φ 1 is at a high level and the gate control signal Φ i is at a low level, the NMOS NMi is not turned on, i is greater than or equal to 2 and less than or equal to N, and the voltage of the inverted input terminal voltage VT1 of the comparator 1 is:

namely: the voltage value of the voltage VT1 is equal to the resistance R_RTCIs divided by the resistance R_RTCThe sum of the resistance value and the resistance value of a resistor R1, wherein R_RTCIs the resistance value of the thermistor RTC.

When the voltage VT1 at the inverting input end of the comparator 1 is larger than the voltage VR1 at the non-inverting input end of the comparator 1, starting the temperature protection circuit; when the inverting input terminal voltage VT1 of the comparator 1 is smaller than the non-inverting input terminal voltage VR1 of the comparator 1, the temperature point at which the temperature protection circuit is activated is not reached, and the temperature protection circuit is not activated.

When the temperature protection circuit is started, the inverting input voltage VT1 of the comparator 1 is made equal to the non-inverting input voltage VR1 of the comparator 1, that is:

the voltage value of VR1 is obtained by proportionally connecting and dividing the voltage of the internal resistor network of the chip in series, the resistance value of the peripheral resistor R1 can be set and adjusted, and the voltage value of V1 is the value of reducing the high level of the gate control signal phi 1 by a threshold voltage. Under the condition that the VR1 voltage, the V1 voltage and the resistance of the peripheral resistor R1 are known, the resistance R of the thermistor RTC can be obtained according to the formula (c)_RTCThen, according to the relationship between the resistance and the temperature of the thermistor RTC, the first temperature point of the corresponding thermistor RTC at that time can be obtained.

When the gate control signal Φ 2 is at a high level, the gate control signals Φ i except Φ 2 are at a low level, the NMOS transistor NM2 is turned on, the gate control signal Φ 2 at the high level is changed to a low level through the not gate 2, so that the PMOS transistor PM2 is turned on, and the gate control signal Φ 2 serves as an on-off control signal of the switch S2, and when the gate control signal Φ 2 is at a high level, the switch S2 is turned on. The source terminal voltage of the NMOS transistor NM2 is a voltage value obtained by lowering the high level of the gate terminal control signal Φ 2 by one threshold voltage, i.e., a voltage V2, and is equal to the source-drain voltage of the PMOS transistor PM2, i.e., VR is equal to V2. After the voltage VR passes through the resistor network, according to the principle of voltage division by the series resistors, the voltage value of VR2 at the positive input end of the comparator 2 is obtained as follows:

namely: the voltage VR2 has a value equal to the sum of the resistances of resistors RF1 and RF2 divided by the sum of the resistances of resistors RF1-RFi multiplied by the voltage VR.

Meanwhile, when the gate control signal Φ 2 is at a high level, the remaining gate control signals Φ i are at a low level, the remaining NMOS transistor NMi is not turned on, i.e., NM1 and NM3-NMN are not turned on, and the voltage of the inverted input terminal voltage VT2 of the comparator 2 is:

when the inverting input terminal voltage VT2 of the comparator 2 is larger than the non-inverting input terminal voltage VR2 of the comparator 2, starting the temperature protection circuit; when the inverting input terminal voltage VT2 of the comparator 2 is smaller than the non-inverting input terminal voltage VR2 of the comparator 2, the temperature point at which the temperature protection circuit is activated is not reached, and the temperature protection circuit is not activated.

When the temperature protection circuit is activated, the inverting input voltage VT2 of the comparator 2 is made equal to the non-inverting input voltage VR2 of the comparator 2, that is:

the voltage value of VR2 is obtained by proportionally connecting and dividing the voltage of the internal resistor network of the chip in series, the resistance value of the peripheral resistor R2 can be set and adjusted, and the voltage value of V2 is the value of reducing the high level of the gate control signal phi 2 by a threshold voltage.

Under the condition that the VR2 voltage, the V2 voltage and the resistance of the peripheral resistor R2 are known, the resistance R of the thermistor RTC can be obtained according to the formula (f)_RTCAccording to the resistance of the thermistor RTCAnd the temperature, the second temperature point of the corresponding thermistor RTC at that time can be obtained.

The working process of the multi-stage temperature detection circuit of the embodiment is described by taking two temperature points as an example, based on the above principle and the like, a high-voltage gate end control signal is sequentially applied to each regulation and control unit, so that multi-stage temperature detection can be realized, that is, the acquisition of N temperature points can be realized by adopting N peripheral resistors R1-RN, one thermistor RTC and two comparators, so that the cost of the temperature detection circuit is reduced, and the occupied area of a chip is smaller.

The multi-section temperature detection circuit is controlled to carry out periodic sampling through the gate end control signals phi 1-phi N. After each cycle of sampling is finished and N temperature points are collected, the sampling device sleeps for a period of time and performs repeated sampling, so that the average current is reduced by introducing time delay, and low power consumption is further realized.