CN108666973B - High-precision over-temperature protection circuit with adjustable threshold - Google Patents
High-precision over-temperature protection circuit with adjustable threshold Download PDFInfo
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- CN108666973B CN108666973B CN201810527534.8A CN201810527534A CN108666973B CN 108666973 B CN108666973 B CN 108666973B CN 201810527534 A CN201810527534 A CN 201810527534A CN 108666973 B CN108666973 B CN 108666973B
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02H—EMERGENCY PROTECTIVE CIRCUIT ARRANGEMENTS
- H02H5/00—Emergency protective circuit arrangements for automatic disconnection directly responsive to an undesired change from normal non-electric working conditions with or without subsequent reconnection
- H02H5/04—Emergency protective circuit arrangements for automatic disconnection directly responsive to an undesired change from normal non-electric working conditions with or without subsequent reconnection responsive to abnormal temperature
- H02H5/047—Emergency protective circuit arrangements for automatic disconnection directly responsive to an undesired change from normal non-electric working conditions with or without subsequent reconnection responsive to abnormal temperature using a temperature responsive switch
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Abstract
A high-precision over-temperature protection circuit with an adjustable threshold belongs to the technical field of electronic circuits. The temperature sensing module comprises a diode type NTC thermistor, the cathode of the diode type NTC thermistor is used as a temperature detection end, and the anode of the diode type NTC thermistor is connected with a first reference current; the subtractor module is used for subtracting the cathode voltage of the diode NTC thermistor from the anode voltage of the diode NTC thermistor to obtain a temperature measurement voltage; the input end of the threshold setting module is connected with a reference voltage, and the output end of the threshold setting module outputs a threshold voltage; the threshold setting module comprises a trimming module, the trimming module is used for generating a trimming code value, and the trimming code value is used for adjusting the threshold voltage; the control output module is used for comparing the temperature measuring voltage with the threshold voltage and generating an over-temperature signal according to the comparison result. The over-temperature protection circuit provided by the invention has the advantages of high detection precision, high detection speed and simple circuit structure, and meanwhile, the protection threshold value of the circuit can be adjusted.
Description
Technical Field
The invention relates to the electronic circuit technology, in particular to a high-precision over-temperature protection circuit with an adjustable threshold value, which can be used for a motor drive circuit.
Background
Because many high power circuits are integrated in an integrated circuit, when the ambient temperature is too high or a power supply short circuit, an internal short circuit, and the like occur, the power consumption of the circuit is increased rapidly, and the chip temperature is also too high to cause the rapid aging or permanent loss of the chip, so that an over-temperature protection circuit is often required to be arranged for the chip to prevent the situations.
Taking a motor driving circuit as an example, a power MOS is generally used as a switching tube in the motor driving circuit, the current is large when the motor works, generally reaching dozens of amperes, and the current is larger once the stalling or short circuit occurs, so that the power MOS must flow large current when working, the temperature of a device can be increased, and the circuit can be damaged if the power MOS cannot be controlled in time. Therefore, in the application of power devices, precise over-temperature protection of circuits is required rapidly.
The traditional over-temperature protection circuit is generally manufactured in a driving chip or is connected with a temperature-sensitive resistor in series on a power MOS. If the temperature sampling module is arranged in the chip, the temperature of the power MOS cannot be accurately sensed, a large error is generated, and if a temperature-sensitive resistor is connected in series with the source end or the drain end of the power MOS, the power is increased, and larger heat is generated.
Disclosure of Invention
Aiming at the defects of large error, inaccurate measurement and the like of the traditional over-temperature protection circuit, the invention provides the high-precision over-temperature protection circuit with the adjustable threshold, which has the advantages of accurate and quick temperature sampling, high precision, adjustable threshold, simple circuit structure and the like.
The technical scheme of the invention is as follows:
a high-precision over-temperature protection circuit with adjustable threshold comprises a temperature sensing module, a subtracter module, a threshold setting module and a control output module,
the temperature sensing module comprises a diode type NTC thermistor D1, the cathode of the diode type NTC thermistor D1 is used as a temperature detection end, and the anode of the diode type NTC thermistor D1 is connected with a first reference current Iref 1;
the subtractor module is used for subtracting the cathode voltage V2 of the diode NTC thermistor D1 from the anode voltage V1 of the diode NTC thermistor D1 to obtain a temperature measurement voltage;
the input end of the threshold setting module is connected with a reference voltage Vref0, and the output end of the threshold setting module outputs a threshold voltage Vref 1;
the threshold setting module comprises a trim module to generate a trim value to adjust the threshold voltage Vref 1;
the control output module is used for comparing the temperature measurement voltage with the threshold voltage Vref1 and generating an over-temperature signal VOUT according to the comparison result.
Specifically, when the over-temperature protection circuit is used for detecting a motor driving circuit, the cathode of the diode type NTC thermistor D1 is tightly connected with the drain of a power MOS tube VD1 of the motor driving circuit.
Specifically, the threshold setting module further includes a first operational amplifier OP1, a first NMOS tube NM1, a second NMOS tube NM2, a third NMOS tube NM3, a fourth NMOS tube NM4, a fifth NMOS tube NM5, a first resistor R1, a second resistor R2, a third resistor R3, a fourth resistor R4, and a fifth resistor R5,
a positive input end of the first operational amplifier OP1 is connected to the reference voltage Vref0, a negative input end thereof is connected to the source of the first NMOS transistor NM1 and one end of the first resistor R1, and an output end thereof is connected to the gate of the first NMOS transistor NM 1; the drain electrode of the first NMOS tube NM1 is connected with a power supply voltage VCC;
one end of the second resistor R2 is connected to the other end of the first resistor R1 and the drain of the second NMOS transistor NM2, and the other end thereof is connected to one end of the third resistor R3 and the drain of the third NMOS transistor NM 3;
one end of the fourth resistor R4 is connected to the other end of the third resistor R3 and the drain of the fourth NMOS transistor NM4, and the other end thereof is connected to the drain of the fifth NMOS transistor NM5 and grounded through the fifth resistor R5;
the trimming module generates a four-bit trimming code value which is respectively connected with the grids of a second NMOS tube NM2, a third NMOS tube NM3, a fourth NMOS tube NM4 and a fifth NMOS tube NM5, and the sources of the second NMOS tube NM2, the third NMOS tube NM3, the fourth NMOS tube NM4 and the fifth NMOS tube NM5 are interconnected and used as the output end of the threshold setting module to output the threshold voltage Vref 1.
Specifically, the threshold setting module further includes a first operational amplifier OP1, a first NMOS tube NM1, a sixth NMOS tube NM6, a seventh NMOS tube NM7, an eighth NMOS tube NM8, a ninth NMOS tube NM9, a sixth resistor R6, a seventh resistor R7, an eighth resistor R8, a ninth resistor R9, and a tenth resistor R10, the trimming module generates a four-bit trimming value to connect the gates of the sixth NMOS tube NM6, the seventh NMOS tube NM7, the eighth NMOS tube NM8, and the ninth NMOS tube NM9, respectively,
a positive input end of the first operational amplifier OP1 is connected to the reference voltage Vref0, a negative input end thereof is connected to the source of the first NMOS transistor NM1, the drain of the sixth NMOS transistor NM6 and one end of the sixth resistor R6, and an output end thereof is connected to the gate of the first NMOS transistor NM 1; the drain electrode of the first NMOS tube NM1 is connected with a power supply voltage VCC;
one end of the seventh resistor R7 is connected to the source of the sixth NMOS transistor NM6, the drain of the seventh NMOS transistor NM7, and the other end of the sixth resistor R6, and the other end thereof is connected to the source of the seventh NMOS transistor NM7, the drain of the eighth NMOS transistor NM8, and one end of the eighth resistor R8, and outputs the threshold voltage Vref1 as the output end of the threshold setting module;
one end of the ninth resistor R9 is connected to the source of the eighth NMOS transistor NM8, the drain of the ninth NMOS transistor NM9, and the other end of the eighth resistor R8, and the other end thereof is connected to the source of the ninth NMOS transistor NM9 and grounded through the tenth resistor R10;
the trimming module generates a four-bit trimming code value to be connected with the gates of a sixth NMOS transistor NM6, a seventh NMOS transistor NM7, an eighth NMOS transistor NM8 and a ninth NMOS transistor NM9, respectively.
Specifically, the subtractor module includes a second operational amplifier OP2, an eleventh resistor R11, a twelfth resistor R12, a thirteenth resistor R13, a fourteenth resistor R14 and a tenth NMOS transistor NM10,
an eleventh resistor R11 and a twelfth resistor R12 are connected in series and in parallel between the subtracted input end of the subtractor module and the ground, and the series point of the eleventh resistor R11 and the twelfth resistor R12 is connected with the positive input end of a second operational amplifier OP 2;
a thirteenth resistor R13 and a fourteenth resistor R14 are connected in series and in parallel between the subtracting input end of the subtractor module and the source of a tenth NMOS tube NM10, and the series point of the thirteenth resistor R13 and the fourteenth resistor R14 is connected with the negative input end of a second operational amplifier OP 2;
the gate of the tenth NMOS transistor NM10 is connected to the output terminal of the second operational amplifier OP2, the drain thereof is connected to the power voltage VCC, and the source thereof is used as the output terminal of the subtractor module to output the temperature measurement voltage and is connected to the second reference current Iref 2.
Specifically, the control output module includes a comparator COMP1, a first inverter INV1, a second inverter INV2, a third inverter INV3, a first PMOS transistor PM1, an eleventh NMOS transistor NM11, a twelfth NMOS transistor NM12, a first schmitt trigger, and a first capacitor C1,
the positive input end of the comparator COMP1 is connected with the threshold voltage Vref1, the negative input end thereof is connected with the temperature measurement voltage, and the output end thereof is connected with the input end of the first inverter INV 1;
the grid electrode of the first PMOS pipe PM1 is connected with the grid electrode of an eleventh NMOS pipe NM1 and the output end of the first inverter INV1, the source electrode of the first PMOS pipe PM1 is connected with the third reference current Iref3, the drain electrode of the first PMOS pipe PM3 is connected with the drain electrodes of the eleventh NMOS pipe NM11 and the twelfth NMOS pipe NM12 and the input end of the first Schmidt trigger, and the first PMOS pipe PM1 is grounded after passing through the first capacitor C1;
the sources of the eleventh NMOS transistor NM11 and the twelfth NMOS transistor NM12 are grounded;
an input end of the third inverter INV3 is connected to the enable signal EN, and an output end thereof is connected to the gate of the twelfth NMOS tube NM 12;
an input end of the second inverter INV2 is connected to an output end of the first schmitt trigger, and an output end thereof outputs the over-temperature signal VOUT.
Specifically, the temperature sensing module further includes a fifteenth resistor R15, and an anode of the diode-type NTC thermistor D1 is connected to the subtractor module through the fifteenth resistor R15.
The invention has the beneficial effects that: the over-temperature protection circuit provided by the invention has the advantages of high detection precision, high detection speed and simple circuit structure, and meanwhile, the protection threshold value of the circuit can be adjusted.
Drawings
Fig. 1 is a structural diagram of an implementation of a high-precision over-temperature protection circuit with adjustable threshold according to the present invention.
Fig. 2 is a schematic diagram of a trimming module.
Fig. 3 is a schematic diagram of another implementation structure of a threshold setting module in a high-precision over-temperature protection circuit with an adjustable threshold according to the present invention.
Detailed Description
The working principle of the present invention will be described in detail below with reference to the accompanying drawings and embodiments.
The invention provides a high-precision over-temperature protection circuit with an adjustable threshold, which comprises a temperature sensing module, a subtracter module, a threshold setting module and a control output module, wherein the temperature sensing module comprises a diode NTC thermistor D1, the characteristic that the conduction voltage drop of the diode NTC thermistor D1 is reduced along with the rise of temperature is utilized, the cathode of the diode NTC thermistor D1 is used as a temperature detection end, the anode of the diode NTC thermistor D1 is connected with a constant first reference current Iref1, and a reference circuit generating the first reference current Iref1 is used for carrying out temperature compensation on the first reference current Iref1, so that the first reference current Iref1 does not change along with the temperature, and the voltage error at two ends of the diode NTC thermistor D1 caused by the change of current is eliminated.
Taking a motor driving circuit as an example, because a power MOS transistor VD1 is generally used as a switching transistor in the motor driving circuit, and the drain temperature of the power MOS transistor VD1 is generally the highest, and the drain material is generally metal and has good thermal conductivity, the cathode of the diode NTC thermistor D1 is tightly connected with the drain of the power MOS transistor VD1 of the motor driving circuit to detect the temperature of the power MOS transistor VD1, and the temperature sensing module can be tightly arranged with the circuit to be detected and located outside a chip integrated by the subtractor module, the threshold setting module and the control output module, so that the temperature detected by the temperature sensing module is more accurate. When the voltage at two ends of the diode type NTC thermistor D1 is low and cannot be compared with the threshold voltage Vref1, a fifteenth resistor R15 can be arranged in the temperature sensing module according to different application conditions, and the anode of the diode type NTC thermistor D1 is connected with the subtractor module after passing through the fifteenth resistor R15, so that protective measures can be taken for circuits at different temperature points according to requirements, so that over-temperature protection is more flexible and accurate, and the fifteenth resistor R15 has a very low temperature coefficient, so that the voltage at two ends of the diode type NTC thermistor does not change along with the temperature, and the error is reduced.
The current of the power MOS transistor is composed of two parts, one part is the motor current, and the other part is the first reference current Iref1 flowing through the diode type NTC thermistor D1. Because the first reference current Iref1 can be negligibly small relative to the current flowing through the power MOS transistor VD1, the extra power consumption generated on the diode-type NTC thermistor D1 is very small, and the extra heat will not be added to the power MOS transistor VD1 due to the excessive power. Meanwhile, the cathode metal of the diode NTC thermistor D1 is directly attached to the drain metal of the power MOS tube VD1, the metal has good heat conduction, and the temperature of the power MOS tube VD1 can be transmitted to the diode NTV thermistor D1 more quickly and accurately, so that the sampling is more accurate and faster.
The working principle of the temperature sensing module is as follows: the grid drive signal VON is used for controlling the power MOS tube VD1, and the drain current of the power MOS tube VD1 is IDThe temperature of the power MOS transistor VD1 will increase with the increase of power, and the constant first reference current Iref1 is inputted to the anode of the diode NTC thermistor D1, and the voltage drop across the diode NTC thermistor will decrease with the increase of temperature.
The subtractor module is used for calculating the conduction voltage drop of the diode-type NTC thermistor D1, the input end of the subtractor module is connected with the anode voltage V1 of the diode-type NTC thermistor D1, the input end of the subtractor module is connected with the cathode voltage V2 of the diode-type NTC thermistor D1, the output end of the subtractor module obtains temperature measurement voltage, namely the sum of the voltages at the two ends of the diode-type NTC thermistor D1 (a fifteenth resistor R15 is also protected in some embodiments), the interference of the voltage between the source and the drain of the power MOS tube VD1 on temperature sampling is eliminated, and a pure voltage value at the two ends of the diode-type NTC thermistor D1 which changes linearly along with the temperature is obtained. As shown in fig. 1 and fig. 3, a circuit implementation structure of the subtractor module is provided, resistance values of the eleventh resistor R11, the twelfth resistor R12, the thirteenth resistor R13 and the fourteenth resistor R14 may be set as required, in some embodiments, the eleventh resistor R11, the twelfth resistor R12, the thirteenth resistor R13 and the fourteenth resistor R14 are set to be identical and have larger resistance values, and due to a clamping effect of the operational amplifier input terminal, voltages at positive and negative input terminals of the second operational amplifier OP2 are equal. The anode voltage of the diode type NTC thermistor D1 is input to the positive input terminal of the subtractor module second operational amplifier OP2 through the eleventh resistor R11, the drain voltage of the power MOS transistor VD1 is input to the negative input terminal of the second operational amplifier OP2 through the thirteenth resistor R13, and the temperature measurement voltage is output to the negative input terminal of the comparator COMP1 of the control output module through the source of the tenth NMOS 10.
Keeping the voltage at the anode of the diode NTC thermistor D1 as V1 and the voltage at the drain of the power MOS transistor VD1 as V2, according to the characteristics of the operational amplifier, it can be derived that the voltage at the forward input terminal of the second operational amplifier is V1/2, so the voltage drop at the thirteenth resistor R13 is V2-V1/2, i.e. the voltage drop at the both ends of the fourteenth resistor R14 is V2-V1/2, so the voltage at the source of the tenth NMOS transistor NM10 is:
that is, the voltage drop across the diode-type NTC thermistor D1 (which may also include a fifteenth resistor R15 in some embodiments) is output to the negative input terminal of the second operational amplifier OP2 of the subtractor module.
The threshold setting module generates a threshold voltage Vref1 according to a reference voltage Vref0 and adjusts the threshold voltage Vref1 according to a trimming code value generated by the trimming module, and the specific steps are that a positive input end of a first operational amplifier OP1 is connected with a fixed reference voltage Vref0, the reference voltage Vref0 is subjected to resistance voltage division, and the trimming module controls the conduction of MOS switch-on light therein to adjust the generated threshold voltage Vref 1. As shown in fig. 2, a circuit implementation structure for generating a one-bit trimming code value in the trimming module includes a sixteenth resistor R16, a fuse Pfuse, a second PMOS transistor MP2, a third PMOS transistor PM3, a thirteenth NMOS transistor NM13, a fourteenth NMOS transistor NM14, a fifteenth NMOS transistor NM15, a second schmitt trigger and a D flip-flop, a gate-drain of the thirteenth NMOS transistor NM13 is interconnected and connected to gates of the fourteenth NMOS transistor NM14 and the fifteenth NMOS transistor NM15 and a fourth reference current ref l 4, and a source thereof is connected to sources of the fourteenth NMOS transistor NM14 and the fifteenth NMOS transistor NM15 and grounded; the grid and the drain of the second PMOS pipe PM2 are interconnected and connected with the drain of a fourteenth NMOS pipe NM14 and the grid of a third PMOS pipe PM3, and the source of the second PMOS pipe PM2 is connected with a power supply voltage VCC after passing through a sixteenth resistor R16; the drain of the third PMOS transistor PM3 is connected to the drain of the fifteenth NMOS transistor NM15 and the input terminal of the second schmitt trigger, and the source thereof is connected to one end of the fuse Pfuse and serves as a fuse control terminal; the other end of the fuse Pfuse is connected with a power supply voltage VCC; the data input end of the D trigger is connected with the output end of the second Schmitt trigger, the clock input end of the D trigger is connected with the clock signal CK, the reset end of the D trigger is connected with the enable signal EN, and the Q output end or the Q non-output end of the D trigger outputs a one-bit trimming code value.
The principle of the trimming module is a current comparator, wherein the fuse wire Pfuse is a current fuse wire, the fuse wire Pfuse can be blown out by increasing a high level on the fuse wire control end Pad, and before the fuse wire Pfuse is not blown out, the resistance R of the fuse wire PfusePfuseApproximately 0, resistance R of fuse Pfuse after blowingPfuseClose to infinity, i.e., open circuit. The fourteenth NMOS transistor NM14 and the fifteenth NMOS transistor NM15 have the same aspect ratio, and when the fuse Pfuse is not blown, R is not blownPfuseR16, VO1 has a tendency to reduce the current flowing through the PM3 of the third PMOS transistor, so that the output of VO1 is high, and when the fuse Pfuse is blown, R is blownPfuse> R16, VO1 tends to increase the current through the third PMOS transistor PM3, and the output of VO1 is low. If a multi-bit trimming code value is needed, a plurality of code value generating circuits are connected in parallel.
As shown in fig. 1, which shows a schematic structural diagram of the threshold setting module in the first embodiment, the forward input terminal of the first operational amplifier OP1 is connected to the reference voltage Vref0 at 1.2V, and the first resistor R1-the fifth resistor R5 divide the reference voltage Vref0 into four voltage values, which are:
the four-bit trimming code value output by the trimming module is connected to the grids of the second NMOS tube to the fifth NMOS tube, when the trimming code value is at a high level, the corresponding MOS tube is opened, the output threshold voltage Vref1 is the drain voltage of the tube, but only one bit of the four-bit trimming code value output each time can be high, namely only one corresponding MOS tube can be switched on each time, so that the method only has 4 trimming combinations, but the voltage division method has good linearity and high precision.
Fig. 3 is a schematic structural diagram of a threshold setting module in the second embodiment, and a connection manner of the MOS transistor is different from that of the threshold setting module in the first embodiment. In the second embodiment, the sixth NMOS transistor NM6 to the ninth NMOS transistor NM9 are respectively connected in parallel to two ends of the sixth resistor R6 to the ninth resistor R9. The threshold voltage Vref1 is output from the connection point of the seventh resistor R7 and the eighth resistor R8, and the output voltage depends on the ratio of the resistance of the threshold voltage Vref1 to ground after the trim value is input and the resistance between the inverting input terminal of the first operational amplifier OP1 to ground. When the MOS tube connected in parallel at two ends of the resistor is opened, the resistor is short-circuited, and the trimming code value has 16 combinations, but the linearity of trimming in the mode is not ideal, and the on-resistance of the MOS tube also influences the accuracy of voltage.
The control output module is used for comparing the temperature measurement voltage output by the subtractor module with a threshold voltage Vref1 generated by the threshold setting module, when the temperature is higher than the set threshold, the temperature measurement voltage is lower than the threshold voltage Vref1, the comparator COMP1 outputs a high voltage, the first inverter INV1 outputs a low voltage, and the overtemperature signal VOUT is output after time delay and shaping. The positive input terminal of the comparator COMP1 in the control output module is connected to a preset threshold voltage Vref1, and the negative input terminal voltage is the voltage difference between two terminals of the diode-type NTC thermistor D1 (some embodiments further include a fifteenth resistor R15). The third reference current Iref3, the first NMOS transistor PM1, the eleventh NMOS transistor NM1 and the first capacitor C1 form a delay loop, a certain signal delay is generated, the enable signal EN enables the control output module, and the first Schmitt trigger shapes the waveform and outputs the waveform. Initially, the temperature is low, the voltage drop across the diode NTC thermistor D1 is large, the output of the comparator COMP1 is low, the low voltage is input to the gates of the first PMOS transistor PM1 and the eleventh NMOS transistor NM11 through the first inverter INV1, the eleventh NMOS transistor NM11 is turned on, the first PMOS transistor PM1 is turned off, the drain voltage of the eleventh NMOS transistor NM11 is changed from high to low, the first capacitor C1 discharges, and the drain voltage is low. When the temperature is too high, the voltage difference between two ends of the diode-type NTC thermistor D1 is reduced, when the temperature measurement voltage V1-V2 is smaller than the threshold voltage Vref1, the output of the comparator COMP1 is high, the temperature measurement voltage V1-V2 is input to the gates of the first PMOS transistor PM1 and the eleventh NMOS transistor NM11 through the first inverter INV1, the first PMOS transistor PM1 is turned on, the eleventh NMOS transistor NM11 is turned off, the drain voltage of the first PMOS transistor PM1 changes from low to high, the third reference current Iref3 starts to charge the first capacitor C1, the drain voltage of the first PMOS transistor PM 35 1 rises slowly, after the drain voltage is shaped by the first schmitt trigger, the rising edge of the drain of the first PMOS transistor PM1 generates a certain delay and then outputs the over-temperature signal VOUT to the driving circuit, and corresponding protection measures are taken, such as being input to the motor driving circuit to turn off the MOS VD transistor 1, so that the motor driving.
In summary, the over-temperature protection circuit provided by the invention integrates the subtractor module, the threshold setting module and the control output module into a chip, the temperature sensing module detects the temperature change by using the temperature-sensitive source diode type NTC resistor D1, and the diode type NTC resistor D1 is arranged outside the chip and is tightly attached to the element to be detected, so that the detection precision is higher, the speed is higher, and the circuit structure is simpler; in addition, the over-temperature protection circuit provided by the invention can adjust the threshold voltage according to the actual condition, adjust the protection threshold of the circuit by adjusting the resistance value of the fifteenth resistor R15 and the trimming code value generated by the trimming module, and can be suitable for any circuit needing temperature protection.
Those skilled in the art can make various other specific changes and combinations based on the teachings of the present invention without departing from the spirit of the invention, and these changes and combinations are within the scope of the invention.
Claims (5)
1. A high-precision over-temperature protection circuit with adjustable threshold is characterized by comprising a temperature sensing module, a subtracter module, a threshold setting module and a control output module,
the temperature sensing module comprises a diode type NTC thermistor (D1), the cathode of the diode type NTC thermistor (D1) is used as a temperature detection end, and the anode of the diode type NTC thermistor is connected with a first reference current (Iref 1);
the subtractor module is used for subtracting the cathode voltage (V2) of the diode NTC thermistor (D1) from the anode voltage (V1) of the diode NTC thermistor (D1) to obtain a temperature measurement voltage;
the input end of the threshold setting module is connected with a reference voltage (Vref 0), and the output end of the threshold setting module outputs a threshold voltage (Vref 1);
the threshold setting module comprises a trim module to generate a trim value to adjust the threshold voltage (Vref 1);
the control output module is used for comparing the temperature measuring voltage with the threshold voltage (Vref 1) and generating an over-temperature signal (VOUT) according to the comparison result;
the control output module comprises a comparator (COMP 1), a first inverter (INV 1), a second inverter (INV 2), a third inverter (INV 3), a first PMOS (PM 1), an eleventh NMOS (NM 11), a twelfth NMOS (NM 12), a first Schmitt trigger and a first capacitor (C1),
the positive input end of the comparator (COMP 1) is connected with the threshold voltage (Vref 1), the negative input end of the comparator is connected with the temperature measurement voltage, and the output end of the comparator is connected with the input end of the first inverter (INV 1);
the grid electrode of the first PMOS tube (PM 1) is connected with the grid electrode of the eleventh NMOS tube (NM 1) and the output end of the first inverter (INV 1), the source electrode of the first PMOS tube is connected with the third reference current (Iref 3), the drain electrode of the first PMOS tube is connected with the drain electrodes of the eleventh NMOS tube (NM 11) and the twelfth NMOS tube (NM 12) and the input end of the first Schmidt trigger, and the first PMOS tube is grounded after passing through the first capacitor (C1);
the sources of the eleventh NMOS transistor (NM 11) and the twelfth NMOS transistor (NM 12) are grounded;
the input end of the third inverter (INV 3) is connected with the enable signal (EN), and the output end of the third inverter is connected with the grid electrode of the twelfth NMOS tube (NM 12);
the input end of the second inverter (INV 2) is connected with the output end of the first Schmitt trigger, and the output end of the second inverter outputs the over-temperature signal (VOUT);
the over-temperature protection circuit is used for detecting a motor driving circuit, and the cathode of the diode type NTC thermistor (D1) is tightly connected with the drain of a power MOS (VD 1) of the motor driving circuit; the source electrode of the power MOS tube (VD 1) is grounded, and the grid electrode of the power MOS tube is connected with a grid electrode driving signal.
2. The threshold-adjustable high-precision over-temperature protection circuit according to claim 1, wherein the threshold setting module further comprises a first operational amplifier (OP 1), a first NMOS transistor (NM 1), a second NMOS transistor (NM 2), a third NMOS transistor (NM 3), a fourth NMOS transistor (NM 4), a fifth NMOS transistor (NM 5), a first resistor (R1), a second resistor (R2), a third resistor (R3), a fourth resistor (R4) and a fifth resistor (R5),
the positive input end of the first operational amplifier (OP 1) is connected with the reference voltage (Vref 0), the negative input end thereof is connected with the source of the first NMOS transistor (NM 1) and one end of the first resistor (R1), and the output end thereof is connected with the grid of the first NMOS transistor (NM 1); the drain electrode of the first NMOS tube (NM 1) is connected with a power supply Voltage (VCC);
one end of the second resistor (R2) is connected with the other end of the first resistor (R1) and the drain electrode of the second NMOS tube (NM 2), and the other end of the second resistor (R2) is connected with one end of the third resistor (R3) and the drain electrode of the third NMOS tube (NM 3);
one end of the fourth resistor (R4) is connected with the other end of the third resistor (R3) and the drain electrode of the fourth NMOS tube (NM 4), and the other end of the fourth resistor (R4) is connected with the drain electrode of the fifth NMOS tube (NM 5) and is grounded after passing through the fifth resistor (R5);
the trimming module generates a four-bit trimming code value which is respectively connected with the grids of a second NMOS (N-channel metal oxide semiconductor) tube (NM 2), a third NMOS tube (NM 3), a fourth NMOS tube (NM 4) and a fifth NMOS tube (NM 5), and only one bit of the four-bit trimming code value is high level;
the sources of the second NMOS transistor (NM 2), the third NMOS transistor (NM 3), the fourth NMOS transistor (NM 4) and the fifth NMOS transistor (NM 5) are interconnected and output the threshold voltage (Vref 1) as the output end of the threshold setting module.
3. The threshold-adjustable high-precision over-temperature protection circuit according to claim 1, wherein the threshold setting module further comprises a first operational amplifier (OP 1), a first NMOS transistor (NM 1), a sixth NMOS transistor (NM 6), a seventh NMOS transistor (NM 7), an eighth NMOS transistor (NM 8), a ninth NMOS transistor (NM 9), a sixth resistor (R6), a seventh resistor (R7), an eighth resistor (R8), a ninth resistor (R9) and a tenth resistor (R10), the trimming module generates a four-bit trimming code value connected to the gates of the sixth NMOS transistor (NM 6), the seventh NMOS transistor (NM 7), the eighth NMOS transistor (NM 8) and the ninth NMOS transistor (NM 9), respectively,
the positive input end of the first operational amplifier (OP 1) is connected with the reference voltage (Vref 0), the negative input end thereof is connected with the source electrode of the first NMOS tube (NM 1), the drain electrode of the sixth NMOS tube (NM 6) and one end of the sixth resistor (R6), and the output end thereof is connected with the grid electrode of the first NMOS tube (NM 1); the drain electrode of the first NMOS tube (NM 1) is connected with a power supply Voltage (VCC);
one end of the seventh resistor (R7) is connected to the source of the sixth NMOS transistor (NM 6), the drain of the seventh NMOS transistor (NM 7) and the other end of the sixth resistor (R6), and the other end thereof is connected to the source of the seventh NMOS transistor (NM 7), the drain of the eighth NMOS transistor (NM 8) and one end of the eighth resistor (R8) and serves as the output end of the threshold setting module to output the threshold voltage (Vref 1);
one end of the ninth resistor (R9) is connected with the source electrode of the eighth NMOS transistor (NM 8), the drain electrode of the ninth NMOS transistor (NM 9) and the other end of the eighth resistor (R8), and the other end of the ninth resistor (R9) is connected with the source electrode of the ninth NMOS transistor (NM 9) and grounded through the tenth resistor (R10);
the trimming module generates a four-bit trimming code value which is respectively connected with the grids of a sixth NMOS transistor (NM 6), a seventh NMOS transistor (NM 7), an eighth NMOS transistor (NM 8) and a ninth NMOS transistor (NM 9).
4. The threshold-adjustable high-precision over-temperature protection circuit according to claim 1, wherein the subtractor module comprises a second operational amplifier (OP 2), an eleventh resistor (R11), a twelfth resistor (R12), a thirteenth resistor (R13), a fourteenth resistor (R14) and a tenth NMOS transistor (NM 10),
an eleventh resistor (R11) and a twelfth resistor (R12) are connected in series and in parallel between the subtracted input end of the subtractor module and the ground, and the series point of the eleventh resistor and the twelfth resistor is connected with the positive input end of a second operational amplifier (OP 2);
a thirteenth resistor (R13) and a fourteenth resistor (R14) are connected in series and in parallel between the subtracting input end of the subtracter module and the source electrode of a tenth NMOS tube (NM 10), and the series point of the thirteenth resistor and the fourteenth resistor is connected with the negative input end of a second operational amplifier (OP 2);
the grid electrode of the tenth NMOS tube (NM 10) is connected with the output end of the second operational amplifier (OP 2), the drain electrode of the tenth NMOS tube is connected with the power supply Voltage (VCC), and the source electrode of the tenth NMOS tube is used as the output end of the subtracter module to output the temperature measuring voltage and is connected with the second reference current (Iref 2).
5. The threshold-adjustable high-precision over-temperature protection circuit according to claim 1, wherein the temperature sensing module further comprises a fifteenth resistor (R15), and an anode of the diode-type NTC thermistor (D1) is connected to the subtractor module through the fifteenth resistor (R15).
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| CN109801580A (en) * | 2018-12-24 | 2019-05-24 | 惠科股份有限公司 | Display panel and its overcurrent protection method and computer readable storage medium |
| CN109861674A (en) * | 2019-04-09 | 2019-06-07 | 深圳市万微微电子技术有限公司 | A kind of realization circuit of high-precision absolute voltage comparator |
| CN110320952B (en) * | 2019-07-22 | 2024-05-31 | 苏州欧普照明有限公司 | Over-temperature protection circuit and system |
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| CN112068631B (en) * | 2020-09-24 | 2021-06-08 | 电子科技大学 | Anti-interference excess temperature protection circuit of low-power consumption |
| CN113204466B (en) * | 2021-04-29 | 2022-11-18 | 山东英信计算机技术有限公司 | Over-temperature protection method and electronic equipment |
| CN113884208B (en) * | 2021-09-09 | 2023-10-10 | 芯原微电子（成都）有限公司 | High-precision over-temperature detection circuit |
| CN115588965B (en) * | 2022-11-11 | 2023-03-17 | 上海芯龙半导体技术股份有限公司南京分公司 | Over-temperature protection circuit and over-temperature protection chip |
| CN116560344A (en) * | 2023-06-05 | 2023-08-08 | 国网甘肃省电力公司临夏供电公司 | Cloud platform-based remote fault diagnosis system for power grid equipment |
| CN118074065A (en) * | 2024-04-19 | 2024-05-24 | 深圳贝特莱电子科技股份有限公司 | Over-temperature protection circuit and control method |
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