CN117650483A - Over-temperature detection circuit of high-side switch and switching power supply - Google Patents
Over-temperature detection circuit of high-side switch and switching power supply Download PDFInfo
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- CN117650483A CN117650483A CN202410122448.4A CN202410122448A CN117650483A CN 117650483 A CN117650483 A CN 117650483A CN 202410122448 A CN202410122448 A CN 202410122448A CN 117650483 A CN117650483 A CN 117650483A
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01K—MEASURING TEMPERATURE; MEASURING QUANTITY OF HEAT; THERMALLY-SENSITIVE ELEMENTS NOT OTHERWISE PROVIDED FOR
- G01K13/00—Thermometers specially adapted for specific purposes
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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
- G01K7/01—Measuring temperature based on the use of electric or magnetic elements directly sensitive to heat ; Power supply therefor, e.g. using thermoelectric elements using semiconducting elements having PN junctions
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02H—EMERGENCY PROTECTIVE CIRCUIT ARRANGEMENTS
- H02H1/00—Details of emergency protective circuit arrangements
- H02H1/0007—Details of emergency protective circuit arrangements concerning the detecting means
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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
- H02H5/044—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 semiconductor device to sense the temperature
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02H—EMERGENCY PROTECTIVE CIRCUIT ARRANGEMENTS
- H02H7/00—Emergency protective circuit arrangements specially adapted for specific types of electric machines or apparatus or for sectionalised protection of cable or line systems, and effecting automatic switching in the event of an undesired change from normal working conditions
- H02H7/10—Emergency protective circuit arrangements specially adapted for specific types of electric machines or apparatus or for sectionalised protection of cable or line systems, and effecting automatic switching in the event of an undesired change from normal working conditions for converters; for rectifiers
- H02H7/12—Emergency protective circuit arrangements specially adapted for specific types of electric machines or apparatus or for sectionalised protection of cable or line systems, and effecting automatic switching in the event of an undesired change from normal working conditions for converters; for rectifiers for static converters or rectifiers
- H02H7/1203—Circuits independent of the type of conversion
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
- H02M1/00—Details of apparatus for conversion
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Abstract
The invention relates to the technical field of power integrated circuits, and discloses an over-temperature detection circuit of a high-side switch and a switching power supply, wherein the over-temperature detection circuit comprises a triode Q1 and a current source, a collector electrode of the triode Q1 is electrically connected with a power supply VCC, and a base electrode of the triode Q1 is electrically connected with an emitter electrode of the triode Q1 and the current source respectively; when the temperature sensor is actually used, the temperature detection is carried out by utilizing the characteristic that the saturation current of the collector junction of the triode rises along with the temperature index, and when the temperature changes, the saturation current of the collector junction of the triode also changes, so that the saturation current of the collector junction of the triode is compared with the current of a current source to generate an over-temperature protection signal, and the influence of noise and voltage drop on the accuracy of over-temperature protection detection is avoided; in addition, because the current detection is realized in a current mode, the invention is not only applicable to intelligent power integrated circuits, but also applicable to high-voltage power integrated circuits, and has good compatibility.
Description
Technical Field
The invention relates to the technical field of power integrated circuits, in particular to an over-temperature detection circuit of a high-side switch and a switching power supply.
Background
The high-side switch, which is a switch circuit commonly applied in production and manufacture, has wide application in electronic equipment such as automobile control and industrial illumination because of cost saving and realization of economical and efficient high-current load control.
Because the high-side switch is widely used for power supply occasions of high-current loads, the loss of the power tube mainly radiates to the surrounding in a heat mode, and therefore the working temperature of the high-side switch is high. In addition, if abnormal conditions such as short circuit or overload occur, the high-side switch has the risk of overheating damage. Therefore, real-time monitoring of temperature and protection of the circuit is critical to normal use of the high-side switch.
At present, the high-side switch is divided into an intelligent power integrated circuit and a high-voltage power integrated circuit according to whether a control chip and a power tube are integrated together, wherein the control chip of the intelligent power integrated circuit and the power tube are integrated together, and the control chip of the high-voltage power integrated circuit and the power tube are arranged separately. For an intelligent power integrated circuit, although the requirements on the flow sheet process are high, a traditional over-temperature protection circuit can be adopted for over-temperature detection protection; for a high-voltage power integrated circuit, the control chip and the power tube can be manufactured by adopting the process with lower cost, but an over-temperature protection circuit is not designed well.
The conventional over-temperature protection circuit usually drops voltage V through BE junction of triode BE To detect temperature and to set the threshold for over-temperature protection using a voltage reference or a resistive divider. A circuit of a conventional over-temperature protection circuit is shown in FIG. 1, in which the BE junction voltage drop of a triode Q1 is used for detectionAnd the resistor R1 and the resistor R2 form a voltage dividing circuit for measuring temperature. From the Shockley equation I of PN junction C =I S *[exp(V BE /V T )-1]It can be seen that the pressure drop V BE The calculation formula of (2) is V BE =V T *ln[（I C /I S ）+1]Wherein I S Is the saturation current of the collector, V T Is an electron thermal voltage, exhibits negative temperature characteristics, and V when the temperature increases BE When the voltage drop on the resistor R1 is larger than the starting threshold value of the triode Q1, the triode Q1 is conducted, and an over-temperature protection signal is output. In fig. 1, the base of the transistor Q1 should be at the same potential as one end of the resistor R1, and the emitter of the transistor Q1 should be at the same potential as the other end of the resistor R1, so that the over-temperature protection threshold will be changed due to the voltage difference.
For the traditional over-temperature protection circuit, if the over-temperature protection circuit is applied to a high-voltage power integrated circuit, namely the triode Q1 is placed on a power tube, in the high-current application, the electric potentials at two ends of the resistor R1 and the triode Q1 are unequal due to the large voltage drop of the power tube, so that the threshold value of over-temperature protection is directly influenced.
The over-temperature insulation circuit in the high-voltage power integrated circuit is shown in fig. 2, an NTC resistor is directly used as a temperature detection device in the circuit, the resistance value of the NTC resistor is reduced along with the temperature rise until the comparator turns over and outputs an OTP signal when (RNTC/R) < (R2/R1). For the circuit shown in fig. 2, the cost of the circuit is high because of the need to design a special comparator and the need for an NTC resistor; in addition, when the circuit is applied to an intelligent power integrated circuit, due to the existence of material thermal resistance, accurate over-temperature protection is difficult to be provided for a large-area power tube.
In combination with the above, when the existing two over-temperature protection circuits perform over-temperature protection detection, the over-temperature detection is realized by comparing the voltages, so that each over-temperature protection circuit is only applicable to the corresponding high-side switch and has poor compatibility; and because the voltage mode is adopted for detection, noise and voltage drop in the circuit environment can bring detection errors and interference, and the over-temperature detection precision is affected.
Disclosure of Invention
In view of the shortcomings of the background technology, the invention provides an over-temperature detection circuit and a switching power supply of a high-side switch, and aims to solve the technical problems that the existing over-temperature protection circuit is poor in compatibility and can only be applied to the corresponding high-side switch, and due to the fact that detection is carried out in a voltage mode, noise and voltage drop in a circuit environment can bring detection errors and interference, and over-temperature detection precision is affected.
In order to solve the technical problems, in a first aspect, the invention provides an over-temperature detection circuit of a high-side switch of a first structure, which comprises a triode Q1 and a current source, wherein a collector of the triode Q1 is electrically connected with a power supply VCC, and a base of the triode Q1 is electrically connected with an emitter of the triode Q1 and the current source respectively;
when the current ICB flowing through the triode Q1 is larger than the current of the current source, the emitter of the triode Q1 outputs a high-level detection signal; when the current ICB flowing through the transistor Q1 is smaller than the current of the current source, the emitter of the transistor Q1 outputs a detection signal of low level.
In a certain implementation manner of the first aspect, the current source includes an NMOS transistor M1 and a resistor R1, where a drain of the NMOS transistor M1 is electrically connected to an emitter of the triode Q1, a source of the NMOS transistor M1 is electrically connected to one end of the resistor R1, and a gate of the NMOS transistor M1 is electrically connected to the other end of the resistor R1 and is grounded.
In a certain implementation manner of the first aspect, the present invention further includes a schmitt trigger SMIT1 and a signal processing unit, where an emitter of the triode Q1 is electrically connected to an input terminal of the schmitt trigger SMIT1, and an output terminal of the schmitt trigger SMIT1 is electrically connected to the signal processing unit, and the signal processing unit is configured to perform inverse processing on an output signal of the schmitt trigger SMIT 1.
In a certain implementation manner of the first aspect, the invention further comprises an NMOS tube M2, a resistor R2 and a switch tube M3; the drain electrode of the NMOS tube M2 is electrically connected with the input end of the Schmidt trigger SMIT1, the source electrode of the NMOS tube M2 is electrically connected with one end of a resistor R2, the grid electrode of the NMOS tube M2 is respectively electrically connected with the other end of the resistor R2 and the input end of a switch tube M3, the output end of the switch tube M3 is grounded, the control end of the switch tube M3 is electrically connected with the output end of the Schmidt trigger SMIT1, the switch tube M3 is conducted when the output end of the Schmidt trigger SMIT1 outputs a high level signal, and the switch tube M3 is turned off when the output end of the Schmidt trigger SMIT1 outputs a low level signal.
In certain embodiments of the first aspect, the NMOS transistor M1 and the NMOS transistor M2 are both depletion NMOS transistors.
In a second aspect, the present invention further provides an over-temperature detection circuit of a high-side switch with another structure, which includes a triode Q2, a bias current generating unit and a current comparing unit; the collector electrode of the triode Q2 is used for being connected with a power supply VCC, and the base electrode of the triode Q2 is electrically connected with the emitter electrode of the triode Q2; the current comparison unit is electrically connected with the bias current generation unit and the emitter of the triode Q2 respectively, and is used for comparing the bias current generated by the bias current generation unit with the current flowing through the triode Q2 and outputting an over-temperature detection signal based on the comparison result.
In an embodiment of the second aspect, the current comparing unit outputs the low-level over-temperature detection signal when the current flowing through the transistor Q2 is greater than the bias current generated by the bias current generating unit, and outputs the high-level over-temperature detection signal when the current flowing through the transistor Q2 is less than the bias current generated by the bias current generating unit.
In a certain embodiment of the second aspect, the present invention further includes a schmitt trigger SMIT2, and the over-temperature detection signal output terminal of the current comparing unit is electrically connected to the input terminal of the schmitt trigger SMIT 2.
In some embodiment of the second aspect, the current comparing unit includes a current mirror, an NMOS transistor N11, an NMOS transistor N12, an NMOS transistor N13, a switching transistor N14, a resistor R11, a resistor R12, a resistor R13, a resistor R14, and an inverter INV2;
the current mirror comprises a main branch, a first slave branch, a second slave branch and a third slave branch, and the first slave branch, the second slave branch and the third slave branch replicate the current flowing through the main branch according to the mirror proportion respectively;
the bias current generating unit is electrically connected with the main branch, and the first auxiliary branch is respectively and electrically connected with the drain electrode of the NMOS tube N11 and the grid electrode of the NMOS tube N13, and provides a first replication current for the drain electrode of the NMOS tube N11; the second slave branch is respectively and electrically connected with the drain electrode of the NMOS tube N12, the grid electrode of the NMOS tube N12 and the grid electrode of the NMOS tube N11, and provides a second replication current for the drain electrode of the NMOS tube N12; the third slave branch is electrically connected with the drain electrode of the NMOS tube N13, and provides a third replication current for the drain electrode of the NMOS tube N13, and the drain electrode of the NMOS tube N13 is an over-temperature detection signal output end of the current comparison unit;
the source electrode of the NMOS tube N11 is grounded through a resistor R11 and is respectively and electrically connected with the emitter electrode of the triode Q2 and one end of a resistor R14, the other end of the resistor R14 is electrically connected with the input end of a switch tube N14, the output end of the switch tube N1 is grounded, the control end of the switch tube N14 is electrically connected with the output end of an inverter INV2, and the input end of the inverter INV2 is electrically connected with the output end of a Schmidt trigger SMIT 2; the source electrode of the NMOS tube N12 is grounded through a resistor R12, and the source electrode of the NMOS tube N13 is grounded through a resistor R13.
In a certain embodiment of the second aspect, the switching tube N14 is an NMOS tube.
In a third aspect, the present invention further provides a switching power supply, including an over-temperature detection circuit of the high-side switch.
Compared with the prior art, the invention has the following beneficial effects: according to the invention, the temperature detection is carried out by utilizing the characteristic that the saturation current of the collector junction of the triode rises along with the temperature index, and when the temperature changes, the saturation current of the collector junction of the triode also changes, so that the saturation current of the collector junction of the triode is compared with the current of a current source to generate an over-temperature protection signal, and the influence of noise and voltage drop on the accuracy of over-temperature protection detection is avoided;
in addition, the current detection is realized in a current mode, so that the invention is not only applicable to intelligent power integrated circuits, but also applicable to high-voltage power integrated circuits, and has good compatibility;
and finally, the invention has simple integral structure, is easy to integrate, and is beneficial to reducing the cost of the integral application scheme.
Drawings
FIG. 1 is a circuit diagram of an over-temperature protection circuit for use in a smart power integrated circuit;
FIG. 2 is a circuit diagram of an over-temperature protection circuit for use in a high voltage power integrated circuit;
fig. 3 is a schematic diagram of an over-temperature detection circuit in the first embodiment;
FIG. 4 is a waveform diagram of the output versus temperature of the circuit of FIG. 3;
FIG. 5 is a circuit diagram of an over-temperature detection circuit in the first embodiment;
fig. 6 is a schematic diagram of an over-temperature detection circuit in the second embodiment;
fig. 7 is a circuit diagram of an over-temperature detection circuit in the second embodiment.
Detailed Description
The invention will now be described in further detail with reference to the accompanying drawings. The drawings are simplified schematic representations which merely illustrate the basic structure of the invention and therefore show only the structures which are relevant to the invention.
Example 1
As shown in fig. 3, an over-temperature detection circuit of a high-side switch comprises a triode Q1 and a current source IA, wherein a collector of the triode Q1 is electrically connected with a power supply VCC, and a base of the triode Q1 is electrically connected with an emitter of the triode Q1 and the current source IA respectively;
when the current ICB flowing through the triode Q1 is larger than the current of the current source IA, the emitter of the triode Q1 outputs a high-level detection signal; when the current ICB flowing through the transistor Q1 is smaller than the current of the current source IA, the emitter of the transistor Q1 outputs a low-level detection signal; the current ICB flowing through the transistor Q1 is the saturation current of the collector junction of the transistor Q1.
For the over-temperature detection circuit in this embodiment, the saturation current of the collector junction of the triode Q1 is detected by utilizing the characteristic that the saturation current of the collector junction of the triode Q1 rises along with the temperature index, and when the temperature changes, the saturation current of the collector junction of the triode Q1 also changes, so that the saturation current of the collector junction of the triode Q1 is compared with the current of the current source IA to generate an over-temperature protection signal, and thus, the influence of noise and voltage drop on the accuracy of over-temperature protection detection is not worried.
The relationship between the detection signal output in the embodiment and the saturation current of the collector junction of the triode Q1 and the temperature is shown in fig. 4, when the temperature rises, the current ICB increases exponentially with the temperature, and when the current ICB is greater than the current generated by the current source IA, the current ICB pulls up the emitter potential of the triode Q1 to a high level state, so as to realize over-temperature detection.
Specifically, an implementation circuit diagram of the over-temperature detection circuit in this embodiment is shown in fig. 5, wherein the current source IA includes an NMOS tube M1 and a resistor R1, a drain electrode of the NMOS tube M1 is electrically connected to an emitter electrode of the triode Q1, a source electrode of the NMOS tube M1 is electrically connected to one end of the resistor R1, a gate electrode of the NMOS tube M1 is electrically connected to the other end of the resistor R1, and the drain electrode is grounded; wherein the NMOS tube M1 is a depletion type NMOS tube.
In actual use, the pull-down current Id generated by the current source IA is calculated as follows: id= -Vth/R1, vth is the threshold voltage of NMOS transistor M1.
In some embodiments, other existing current generation circuits may be used for the current source IA, and the current source IA only needs to generate a pull-down current for pulling down the emitter of the transistor Q1. One embodiment of current source IA may be such as to generate a reference current by having a reference voltage applied across a reference resistor and then replicate the reference current using a current mirror cell, which may be in the form of an NMOS tube.
In actual use, although a high-level detection signal can be generated by comparing the magnitude of the current ICB with the magnitude of the current Id, if the emitter signal of the triode Q1 is directly output, the waveform of the output detection signal fluctuates, based on which, in order to ensure the waveform stability of the detection signal, in fig. 5, the invention further includes a schmitt trigger SMIT1 and a signal processing unit, the emitter of the triode Q1 is electrically connected with the input terminal of the schmitt trigger SMIT1, the output terminal of the schmitt trigger SMIT1 is electrically connected with the signal processing unit, and the signal processing unit is used for performing inverse processing on the output signal of the schmitt trigger SMIT 1.
Specifically, the signal processing unit is an inverter INV1. During actual use, the schmitt trigger SMIT1 performs primary inversion on the detection signal, and the inverter INV1 performs secondary inversion on the detection signal, so that the waveform of the finally output signal OTP is ensured to be the same as that of the detection signal output by the emitter of the triode Q1, and the signal OTP is free from floating, thereby being beneficial to actual application.
In addition, in actual use, if the temperature detection point is only set as one detection point, when the temperature is frequently changed near the detection point, the output signal OTP has oscillation conditions, which is unfavorable for actual application, and based on the invention, the invention also comprises an NMOS tube M2, a resistor R2 and a switch tube M3; the drain electrode of the NMOS tube M2 is electrically connected with the input end of the Schmidt trigger SMIT1, the source electrode of the NMOS tube M2 is electrically connected with one end of a resistor R2, the grid electrode of the NMOS tube M2 is respectively electrically connected with the other end of the resistor R2 and the input end of a switch tube M3, the output end of the switch tube M3 is grounded, the control end of the switch tube M3 is electrically connected with the output end of the Schmidt trigger SMIT1, the switch tube M3 is conducted when the output end of the Schmidt trigger SMIT1 outputs a high level signal, and the switch tube M3 is turned off when the output end of the Schmidt trigger SMIT1 outputs a low level signal. Wherein the NMOS transistors M2 are depletion type NMOS transistors.
Specifically, in this embodiment, the switching tube M3 is an NMOS tube, the drain electrode of the NMOS tube is the input end of the switching tube M3, the source electrode of the NMOS tube is the output end of the switching tube M3, and the gate electrode of the NMOS tube is the control end of the switching tube M3.
In actual use, different temperature detection points can be set by controlling the on-off of the switch tube M3.
In this example, in order to improve the accuracy of the over-temperature detection point, the temperature characteristics of the resistors R1 and R2 are the same as the Vth of the NMOS transistor M1 and the temperature characteristics of the NMOS transistor M2.
The circuit shown in fig. 5 is analyzed, and when the switching tube M3 is turned on, a current ihsy=vth/R2 flowing through the resistor R2;
when the temperature rises from low to high, the signal VTOP is initially in a low level state, the Schmitt trigger SMIT1 outputs a high level to enable the switching tube M3 to be conducted, and the signal OTP output by the inverter INV1 is still in a low level; when ICB > (Id+Ihsy), namely when the temperature T reaches an over-temperature protection point, the signal VOTP is turned to a high level, the Schmidt trigger SMIT1 outputs a low level signal to turn off the switching tube M3, the inverter INV1 outputs a high level signal OTP, and the control chip of the high-side switch can stop working due to the high level signal OTP;
then the temperature of the control chip starts to decrease until ICB < Id, namely the temperature T reaches an over-temperature protection recovery point; then the signal VOTP is pulled down to a low level, the Schmidt trigger SMIT1 outputs a high level, the switching tube M3 is conducted, the signal OTP output by the inverter INV1 returns to the low level, and the control chip of the high-side switch is enabled to work again.
Example two
As shown in fig. 6, the present invention further provides an over-temperature detection circuit of a high-side switch with another structure, which comprises a triode Q2, a bias current generating unit 1 and a current comparing unit 2; the collector electrode of the triode Q2 is used for being connected with a power supply VCC, and the base electrode of the triode Q2 is electrically connected with the emitter electrode of the triode Q2; the current comparing unit 2 is electrically connected to the bias current generating unit 1 and the emitter of the transistor Q2, respectively, for comparing the bias current generated by the bias current generating unit with the current flowing through the transistor Q2, and outputting an over-temperature detection signal based on the comparison result.
Specifically, in the present embodiment, the current comparing unit 2 outputs the over-temperature detection signal of a low level when the current flowing through the transistor Q2 is larger than the bias current generated by the bias current generating unit, and outputs the over-temperature detection signal of a high level when the current flowing through the transistor Q2 is smaller than the bias current generated by the bias current generating unit.
Specifically, in this embodiment, the bias current generating unit 1 is an existing current generating circuit, and only needs to generate one bias current, where the bias current I is a negative temperature characteristic or a zero temperature characteristic, and the specific embodiment may be set according to actual requirements.
In this embodiment, an implementation circuit diagram of the over-temperature detection circuit is shown in fig. 4, wherein the current comparing unit 2 includes a current mirror 20, an NMOS transistor N11, an NMOS transistor N12, an NMOS transistor N13, a switch transistor N14, a resistor R11, a resistor R12, a resistor R13, a resistor R14, and an inverter INV2;
the current mirror 20 comprises a main branch 200, a first slave branch 201, a second slave branch 202 and a third slave branch 203, the first slave branch 201, the second slave branch 202 and the third slave branch 203 reproducing the current flowing through the main branch 200 in mirror proportion, respectively;
the bias current generating unit 1 is electrically connected with the main branch 200, and the first sub-branch 201 is respectively electrically connected with the drain electrode of the NMOS tube N11 and the grid electrode of the NMOS tube N13, and provides a first replication current for the drain electrode of the NMOS tube N11; the second slave branch 202 is electrically connected with the drain electrode of the NMOS transistor N12, the gate electrode of the NMOS transistor N12, and the gate electrode of the NMOS transistor N11, respectively, and provides a second replica current to the drain electrode of the NMOS transistor N12; the third slave branch 203 is electrically connected with the drain electrode of the NMOS tube N13, and provides a third replica current for the drain electrode of the NMOS tube N13, wherein the drain electrode of the NMOS tube N13 is an over-temperature detection signal output end of the current comparison unit 2;
the source electrode of the NMOS tube N11 is grounded through a resistor R11 and is respectively and electrically connected with the emitter electrode of the triode Q2 and one end of a resistor R14, the other end of the resistor R14 is electrically connected with the input end of a switch tube N14, the output end of the switch tube N1 is grounded, the control end of the switch tube N14 is electrically connected with the output end of an inverter INV2, and the input end of the inverter INV2 is electrically connected with the output end of a Schmidt trigger SMIT 2; the source of the NMOS tube N12 is grounded through a resistor R12, and the source of the NMOS tube N13 is grounded through a resistor R13.
In the present embodiment, the magnitude of the bias current I generated by the bias current generating unit 1 is required as follows:
assuming that the gate-source voltage of the NMOS transistor N11 is Vgs1, the gate-source voltage of the NMOS transistor N12 is Vgs2, and the equivalent resistance of the resistor R11 and the resistor R14 connected in parallel is Rz, i= (Vgs 2-Vgs 1)/Rz, the magnitude of the current I can be adjusted by adjusting the magnitudes of the resistors R11 and R14 and by adjusting the dimensions of the NMOS transistor N11 and N12, and the magnitude of the comparison point current can be adjusted by adjusting the magnitude of the current I; in addition, because Vgs2-Vgs1 are positive temperature characteristics and bias current I is zero temperature drift or negative temperature drift characteristics, it is necessary to make resistor R11 and resistor R12 be of the positive temperature drift type;
the current comparing unit 2 outputs the over-temperature detection signal in different level states by comparing the bias current I with the current ICB, so as to realize over-temperature detection, for example, when the temperature is higher than the protection temperature, the signal OTP is the over-temperature detection signal in high level, and when the temperature is lower than the normal temperature, the signal OTP is the over-temperature detection signal in low level due to the existence of the schmitt trigger SMIT 2.
Specifically, in fig. 7, the switching tube N14 is an NMOS tube, and when a high-level signal is input to the gate of the NMOS tube, the NMOS tube is turned on;
in addition, the main branch 200 includes a PMOS pipe P11, the first slave branch 201 includes a PMOS pipe P12, the second slave branch 202 includes a PMOS pipe P13, and the third slave branch includes a PMOS pipe P14; the source electrode of the PMOS tube P11 is respectively and electrically connected with the source electrode of the PMOS tube P12, the source electrode of the PMOS tube P13 and the source electrode of the PMOS tube P14 for accessing the power supply VCC, and the grid electrode of the PMOS tube P11 is respectively and electrically connected with the drain electrode of the PMOS tube P11, the grid electrode of the PMOS tube P12, the grid electrode of the PMOS tube P13 and the source electrode of the PMOS tube P14.
In actual use, the ratio of the width to length ratios of the PMOS transistor P12, the PMOS transistor P13, the PMOS transistor P14 and the PMOS transistor P11 can be adjusted according to actual requirements to adjust the current replication ratios of the first slave branch 201, the second slave branch 202 and the third slave branch 202.
In addition, in fig. 7, the present invention further includes a schmitt trigger SMIT2, and the over-temperature detection signal output terminal of the current comparing unit 2 is electrically connected to the input terminal of the schmitt trigger SMIT 2. In actual use, the overtemperature detection signal output by the current comparison unit 2 can be shaped through the schmitt trigger SMIT2, so that the fluctuation of the overtemperature detection signal is small, and two temperature detection points are arranged to avoid the oscillation of the overtemperature detection signal.
In addition, compared with the circuit of fig. 5 in the first embodiment, the output of the schmitt trigger SMIT2 can be turned over when the voltage fluctuation with mv level is present on the resistor R4 of the circuit in the first embodiment, so that the response speed is faster, and the circuit can be suitable for high-response application occasions, and the PMOS transistor P11, the PMOS transistor P12, the PMOS transistor P13, the PMOS transistor P14, the NMOS transistor N11, the NMOS transistor N12, the NMOS transistor N13 and the NMOS transistor N14 in fig. 7 are all enhancement type MOS transistors.
In summary, as can be obtained from the first embodiment and the second embodiment, the present invention performs temperature detection by utilizing the characteristic that the saturation current of the collector junction of the triode Q1 rises along with the temperature index, when the temperature changes, the saturation current of the collector junction of the triode Q1 also changes, so that the saturation current of the collector junction of the triode Q1 is compared with the current of the current source IA to generate an overtemperature protection signal, and thus, the influence of noise and voltage drop on the precision of the overtemperature protection detection is not worried;
in addition, the current detection is realized in a current mode, so that the invention is not only applicable to intelligent power integrated circuits, but also applicable to high-voltage power integrated circuits, and has good compatibility;
and finally, the invention has simple integral structure, is easy to integrate, and is beneficial to reducing the cost of the integral application scheme.
Example III
The embodiment provides a switching power supply, which comprises an over-temperature detection circuit of a high-side switch in the first embodiment or the second embodiment.
The present invention has been made in view of the above-described circumstances, and it is an object of the present invention to provide a portable electronic device capable of performing various changes and modifications without departing from the scope of the technical spirit of the present invention. The technical scope of the present invention is not limited to the description, but must be determined according to the scope of claims.
Claims (10)
1. The over-temperature detection circuit of the high-side switch is characterized by comprising a triode Q1 and a current source, wherein a collector electrode of the triode Q1 is electrically connected with a power supply VCC, and a base electrode of the triode Q1 is electrically connected with an emitter electrode of the triode Q1 and the current source respectively;
when the current ICB flowing through the triode Q1 is larger than the current of the current source, the emitter of the triode Q1 outputs a high-level detection signal; when the current ICB flowing through the transistor Q1 is smaller than the current of the current source, the emitter of the transistor Q1 outputs a detection signal of low level.
2. The over-temperature detection circuit of a high-side switch according to claim 1, wherein the current source comprises an NMOS tube M1 and a resistor R1, a drain electrode of the NMOS tube M1 is electrically connected with an emitter electrode of the triode Q1, a source electrode of the NMOS tube M1 is electrically connected with one end of the resistor R1, a gate electrode of the NMOS tube M1 is electrically connected with the other end of the resistor R1, and the drain electrode is grounded.
3. The over-temperature detection circuit of the high-side switch according to claim 2, further comprising a schmitt trigger SMIT1 and a signal processing unit, wherein an emitter of the triode Q1 is electrically connected with an input end of the schmitt trigger SMIT1, an output end of the schmitt trigger SMIT1 is electrically connected with the signal processing unit, and the signal processing unit is used for performing inverse processing on an output signal of the schmitt trigger SMIT 1.
4. The over-temperature detection circuit of a high-side switch according to claim 3, further comprising an NMOS tube M2, a resistor R2, and a switching tube M3; the drain electrode of the NMOS tube M2 is electrically connected with the input end of the Schmidt trigger SMIT1, the source electrode of the NMOS tube M2 is electrically connected with one end of a resistor R2, the grid electrode of the NMOS tube M2 is respectively electrically connected with the other end of the resistor R2 and the input end of a switch tube M3, the output end of the switch tube M3 is grounded, the control end of the switch tube M3 is electrically connected with the output end of the Schmidt trigger SMIT1, the switch tube M3 is conducted when the output end of the Schmidt trigger SMIT1 outputs a high level signal, and the switch tube M3 is turned off when the output end of the Schmidt trigger SMIT1 outputs a low level signal.
5. The over-temperature detection circuit of claim 4, wherein the NMOS transistor M1 and the NMOS transistor M2 are depletion NMOS transistors.
6. The over-temperature detection circuit of the high-side switch is characterized by comprising a triode Q2, a bias current generating unit and a current comparing unit; the collector electrode of the triode Q2 is used for being connected with a power supply VCC, and the base electrode of the triode Q2 is electrically connected with the emitter electrode of the triode Q2; the current comparison unit is electrically connected with the bias current generation unit and the emitter of the triode Q2 respectively, and is used for comparing the bias current generated by the bias current generation unit with the current flowing through the triode Q2 and outputting an over-temperature detection signal based on the comparison result.
7. The over-temperature detection circuit of a high-side switch according to claim 6, wherein the current comparing unit outputs the low-level over-temperature detection signal when the current flowing through the transistor Q2 is larger than the bias current generated by the bias current generating unit, and outputs the high-level over-temperature detection signal when the current flowing through the transistor Q2 is smaller than the bias current generated by the bias current generating unit.
8. The over-temperature detection circuit of a high-side switch according to claim 6 or 7, further comprising a schmitt trigger SMIT2, wherein an over-temperature detection signal output terminal of the current comparison unit is electrically connected to an input terminal of the schmitt trigger SMIT 2.
9. The over-temperature detection circuit of the high-side switch according to claim 8, wherein the current comparison unit comprises a current mirror, an NMOS transistor N11, an NMOS transistor N12, an NMOS transistor N13, a switch transistor N14, a resistor R11, a resistor R12, a resistor R13, a resistor R14, and an inverter INV2;
the current mirror comprises a main branch, a first slave branch, a second slave branch and a third slave branch, and the first slave branch, the second slave branch and the third slave branch replicate the current flowing through the main branch according to the mirror proportion respectively;
the bias current generating unit is electrically connected with the main branch, and the first auxiliary branch is respectively and electrically connected with the drain electrode of the NMOS tube N11 and the grid electrode of the NMOS tube N13, and provides a first replication current for the drain electrode of the NMOS tube N11; the second slave branch is respectively and electrically connected with the drain electrode of the NMOS tube N12, the grid electrode of the NMOS tube N12 and the grid electrode of the NMOS tube N11, and provides a second replication current for the drain electrode of the NMOS tube N12; the third slave branch is electrically connected with the drain electrode of the NMOS tube N13, and provides a third replication current for the drain electrode of the NMOS tube N13, and the drain electrode of the NMOS tube N13 is an over-temperature detection signal output end of the current comparison unit;
the source electrode of the NMOS tube N11 is grounded through a resistor R11 and is respectively and electrically connected with the emitter electrode of the triode Q2 and one end of a resistor R14, the other end of the resistor R14 is electrically connected with the input end of a switch tube N14, the output end of the switch tube N1 is grounded, the control end of the switch tube N14 is electrically connected with the output end of an inverter INV2, and the input end of the inverter INV2 is electrically connected with the output end of a Schmidt trigger SMIT 2; the source electrode of the NMOS tube N12 is grounded through a resistor R12, and the source electrode of the NMOS tube N13 is grounded through a resistor R13.
10. A switching power supply comprising an over-temperature detection circuit of a high-side switch according to any one of claims 1 to 9.
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
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| CN118554928A (en) * | 2024-07-25 | 2024-08-27 | 瓴芯电子科技(无锡)有限公司 | High-side switch circuit |
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| CN101102039A (en) * | 2007-04-12 | 2008-01-09 | 无锡博创微电子有限公司 | MOS type over-temperature protection circuit |
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| CN106055008A (en) * | 2016-06-15 | 2016-10-26 | 泰凌微电子（上海）有限公司 | Current biasing circuit and method for improving positive temperature coefficient |
| CN114353976A (en) * | 2021-12-23 | 2022-04-15 | 普冉半导体(上海)股份有限公司 | Temperature detection circuit |
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| CN101102039A (en) * | 2007-04-12 | 2008-01-09 | 无锡博创微电子有限公司 | MOS type over-temperature protection circuit |
| CN204008833U (en) * | 2014-06-23 | 2014-12-10 | 湖南大学 | A kind of novel triode reverse saturation current tester |
| CN106055008A (en) * | 2016-06-15 | 2016-10-26 | 泰凌微电子（上海）有限公司 | Current biasing circuit and method for improving positive temperature coefficient |
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| CN118554928A (en) * | 2024-07-25 | 2024-08-27 | 瓴芯电子科技(无锡)有限公司 | High-side switch circuit |
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