CN116048178A - Current-limiting protection circuit, chip and electronic equipment based on temperature - Google Patents

Current-limiting protection circuit, chip and electronic equipment based on temperature Download PDF

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Publication number
CN116048178A
CN116048178A CN202310086237.5A CN202310086237A CN116048178A CN 116048178 A CN116048178 A CN 116048178A CN 202310086237 A CN202310086237 A CN 202310086237A CN 116048178 A CN116048178 A CN 116048178A
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temperature
signal
unit
current limiting
current
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吴文海
叶峥杰
吴传奎
宋志军
曾文君
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Shanghai Awinic Technology Co Ltd
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Shanghai Awinic Technology Co Ltd
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Priority to CN202310086237.5A priority Critical patent/CN116048178A/en
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    • G—PHYSICS
    • G05—CONTROLLING; REGULATING
    • G05F—SYSTEMS FOR REGULATING ELECTRIC OR MAGNETIC VARIABLES
    • G05F1/00—Automatic systems in which deviations of an electric quantity from one or more predetermined values are detected at the output of the system and fed back to a device within the system to restore the detected quantity to its predetermined value or values, i.e. retroactive systems
    • G05F1/10—Regulating voltage or current
    • G05F1/46—Regulating voltage or current wherein the variable actually regulated by the final control device is dc
    • G05F1/56—Regulating voltage or current wherein the variable actually regulated by the final control device is dc using semiconductor devices in series with the load as final control devices
    • G05F1/565—Regulating voltage or current wherein the variable actually regulated by the final control device is dc using semiconductor devices in series with the load as final control devices sensing a condition of the system or its load in addition to means responsive to deviations in the output of the system, e.g. current, voltage, power factor
    • G05F1/567—Regulating voltage or current wherein the variable actually regulated by the final control device is dc using semiconductor devices in series with the load as final control devices sensing a condition of the system or its load in addition to means responsive to deviations in the output of the system, e.g. current, voltage, power factor for temperature compensation
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02D—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN INFORMATION AND COMMUNICATION TECHNOLOGIES [ICT], I.E. INFORMATION AND COMMUNICATION TECHNOLOGIES AIMING AT THE REDUCTION OF THEIR OWN ENERGY USE
    • Y02D10/00—Energy efficient computing, e.g. low power processors, power management or thermal management

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  • Physics & Mathematics (AREA)
  • Electromagnetism (AREA)
  • General Physics & Mathematics (AREA)
  • Radar, Positioning & Navigation (AREA)
  • Automation & Control Theory (AREA)
  • Continuous-Control Power Sources That Use Transistors (AREA)

Abstract

The application is applied to the technical field of integrated circuits, and provides a temperature-based current limiting protection circuit, a chip and electronic equipment, wherein the circuit comprises a feedback control unit, a reference voltage unit, a temperature regulating unit and a power unit, and the temperature regulating unit is used for generating a pull-down signal according to the current temperature; the reference voltage unit is used for determining a reference signal according to the pull-down signal; the feedback control unit is used for comparing the reference signal with the sampling signal of the power unit and determining a control signal of the power unit according to a comparison result; the power unit is used for determining an output signal according to the control signal. Therefore, after the current limiting state is entered, the current limiting threshold value is not triggered to turn back immediately, and the output current capacity is not reduced. The current limiting threshold value is further reduced along with the increase of the input-output voltage difference, so that the junction temperature of the chip is reduced, and the circuit or the chip can work in a current limiting state for a long time without being burnt by power consumption generated by current limiting.

Description

Current-limiting protection circuit, chip and electronic equipment based on temperature
Technical Field
The present invention relates to the field of integrated circuits, and in particular, to a temperature-based current limiting protection circuit, a chip, and an electronic device.
Background
In order to protect the chip from being burnt out due to an excessively high current value under the condition that the load is instantaneously weighted or short circuit occurs, a current limiting protection circuit is added into the chip. The current limiting protection circuit generally samples the output current/voltage in the output circuit of the chip, compares the sampled output current/voltage with the reference current/voltage, and limits the output current of the output circuit according to the comparison result.
However, the reference current/voltage of the current limiting protection circuit is a fixed value, that is, the current limiting threshold is a fixed value. Furthermore, the output current of the chip is unchanged when the current limiting protection circuit is in a current limiting state, but as the difference value between the input voltage and the output voltage is increased, the power loss of the chip is also increased, and the junction temperature of the chip is increased. Most chips are also provided with an over-temperature protection circuit, and the power path of the load is cut off when the temperature of the chip is too high. If the junction temperature of the chip is higher and higher, the threshold value point of the over-temperature protection circuit in the chip is exceeded, so that the over-temperature protection circuit can cut off a power path connected with a load, the load is powered down, and the normal operation of equipment is affected.
Disclosure of Invention
The application provides a current-limiting protection circuit, chip and electronic equipment based on temperature, can not trigger current-limiting threshold immediately after entering current-limiting state and turn back, can not lead to output current ability to reduce. The current limiting threshold value is further reduced along with the increase of the input-output voltage difference, so that the junction temperature is reduced, and the circuit or the chip can work in a current limiting state for a long time without being burnt by power consumption generated by current limiting.
In a first aspect, a temperature-based current limiting protection circuit is provided, the circuit comprising a feedback control unit, a reference voltage unit, a temperature regulation unit and a power unit, wherein the temperature regulation unit is used for generating a pull-down signal according to the current temperature; the reference voltage unit is used for determining a reference signal according to the pull-down signal; the feedback control unit is used for comparing the reference signal with the sampling signal of the power unit and determining a control signal of the power unit according to a comparison result; the power unit is used for determining an output signal according to the control signal.
In the above scheme, the pull-down signal may be a pull-down voltage or a pull-down current, the reference signal may be a reference voltage or a reference current, the output signal may be an output voltage or an output current, and the sampling signal may be a sampling voltage or a sampling current. The circuit can adjust the reference voltage according to the temperature, and then can adjust the current limiting threshold value, so that after the current limiting state is entered, the current limiting threshold value can be adjusted down after the temperature of the chip reaches the junction temperature, and the circuit or the chip can work in the current limiting state for a long time without being burnt by the power consumption generated by the current limiting.
With reference to the first aspect, in some implementations, the circuit further includes a sampling unit, where the sampling unit is configured to collect an output signal of the power unit to obtain a sampled signal.
With reference to the first aspect, in some implementations, the feedback control unit is configured to compare the reference signal with a sampling signal corresponding to the output signal, and when the sampling signal does not reach the reference signal, the feedback control unit determines the control signal as the first control signal; when the sampling signal reaches the reference signal, the feedback control unit determines the control signal as a second control signal; the first control signal enables the output signal of the power unit to be smaller than a set threshold value, and the second control signal enables the output signal of the power unit to be equal to the set threshold value.
With reference to the first aspect, in some implementations, the temperature adjustment unit is configured to generate a temperature reference signal according to a temperature; the temperature adjusting unit is also used for determining a pull-down signal according to the temperature reference signal and the reference signal, wherein the pull-down signal is used for indicating whether the temperature reference signal reaches the reference signal.
With reference to the first aspect, in some implementations, when the temperature reference signal does not reach the base signal, the temperature adjustment unit determines the pull-down signal as the first pull-down signal; when the temperature reference signal reaches the reference signal, the temperature adjusting unit determines the pull-down signal as a second pull-down signal; the reference signal determined by the reference voltage unit according to the second pull-down signal is smaller than the reference signal determined by the reference voltage unit according to the first pull-down signal.
With reference to the first aspect, in some implementations, the temperature adjustment unit includes a temperature acquisition element for generating a temperature reference signal that is positively or negatively correlated with the current temperature.
With reference to the first aspect, in some implementations, the temperature acquisition element is one or more transistors.
With reference to the first aspect, in some implementations, the temperature adjustment unit further includes an operational amplifier for determining the pull-down signal based on the temperature reference signal and the reference signal.
With reference to the first aspect, in some implementations, the temperature adjustment unit is further configured to determine that the pull-down signal is not zero based on the sample signal reaching the reference signal and the temperature reference signal reaching the reference signal.
In a second aspect, a chip is provided, in which the temperature-based current limiting protection circuit according to any of the first aspects is formed.
In a third aspect, an electronic device is provided, the electronic device comprising a chip having a temperature-based current limiting protection circuit according to any of the first aspects formed therein.
Drawings
In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings that are required to be used in the description of the embodiments will be briefly described below.
Fig. 1 is a schematic circuit diagram of a current limiting protection circuit with a fixed current limiting threshold according to an embodiment of the present application;
fig. 2 is a schematic structural diagram of a field effect transistor according to an embodiment of the present application;
fig. 3 is a schematic diagram of an output current curve of a current limiting protection circuit with a fixed current limiting threshold according to an embodiment of the present application;
FIG. 4 is a schematic circuit diagram of a current limiting protection circuit with reduced current limiting threshold after an output current reaches the current limiting threshold according to an embodiment of the present application;
FIG. 5 is a schematic diagram of a current limiting protection circuit according to an embodiment of the present disclosure, wherein the current limiting threshold is reduced after the output current reaches the current limiting threshold;
FIG. 6 is a schematic diagram of an output current of a temperature-based current limiting protection circuit according to an embodiment of the present disclosure;
fig. 7 is a schematic structural diagram of a temperature-based current limiting protection circuit according to an embodiment of the present application;
fig. 8 is a schematic circuit diagram of a temperature-based current limiting protection circuit according to an embodiment of the present application.
Detailed Description
Illustrative embodiments of the present application include, but are not limited to, a temperature-based current limiting protection circuit, chip, and electronic device.
In order to protect the chip from being burnt out due to excessively high current value under the condition of instant load aggravation or short circuit occurrence, a current limiting protection circuit, such as an operational amplifier output short circuit current limiting circuit, a low dropout linear voltage regulator and the like, is added into the chip. In order to avoid the situation that the current in the chip suddenly increases or the chip is damaged due to short circuit of the output end of the chip and the like caused by suddenly reducing the load of the circuit, a current limiting protection circuit is required to be integrated inside the chip. The current limiting protection circuit has the function that when the current on the protected device exceeds a set current limiting threshold value, the current limiting protection circuit enters a current limiting state, the output current of the power tube is limited to the size of the current limiting threshold value, and when the output current of the power tube is gradually reduced, the system automatically returns to a normal working state, so that the function of protecting a chip is achieved.
Illustratively, as shown in fig. 1, fig. 1 shows a circuit diagram of a current limiting protection circuit with a fixed current limiting threshold. The current-limiting protection circuit comprises Metal-Oxide-semiconductor field effect transistors (MOSFET, MOS tube for short) M0, M1 and M2, an operational amplifier (operational amplifier, operational amplifier for short) csamp and main_amp, and a resistor R SET 、R L Capacitance C L . Wherein M0 is an output tube, namely a power tube, in particular an N-channel MOS (N-channel MOS, NM) tube in the MOS tubeThe structure of the NMOS transistor is shown in fig. 2, and it can be seen from fig. 2 that the NMOS transistor includes a drain (D-pole), a Gate (G-pole), and a source (S-pole). M1 is a sampling tube, and specifically is an NMOS tube. The size proportionality coefficient of the power tube M0 and the sampling tube M1 is K:1.csamp is a clamp operational amplifier, main_amp is a current limiting and regulating main operational amplifier.
The power end of the current-limiting regulating main operational amplifier main_amp is connected with the input voltage V IN The negative input end is connected with the reference voltage V REF Positive input and M2D pole connection resistor R SET One end of the resistor R SET The other end of which is grounded. The output end of main_amp is connected with the G pole of the power tube M0 and the G pole of the sampling tube M1. The S electrode of the power tube M0 and the sampling tube M1 are connected with an input voltage V IN The D pole of the power tube M0 is connected with the positive input end of the clamp operational amplifier csamp and the resistor R L One end of (C) capacitor L And output voltage V OUT . Resistor R L And the other end of (C) and the capacitor C L The other end of which is grounded. The D pole of the sampling tube M1 is connected with the negative input end of the clamp operational amplifier csamp and the S pole of the sampling tube M2. The G pole of M2 is connected with the output end of the clamp operational amplifier csamp.
As can be seen from the above circuit structure, the D-pole current of M0 is the output current I L The output current is simultaneously connected with the positive input end of the clamp operational amplifier csamp and the resistor R L Capacitance C L Corresponding to one end of the output voltage V OUT . M0 is used as a power tube, the circuit part is a power path, and when the voltage V is input in the power path IN And output voltage V OUT When the difference of (1) increases, the output current I L Increasing. The clamping operational amplifier csamp and M2 can make the D pole voltages of M0 and M1 equal, and can make the sampling current I when the size proportionality coefficient of M0 and M1 is K:1 SET Also increase in equal proportion, wherein I SET ＝I L and/K. Further, the resistor R is made SET The upper voltage, i.e. the voltage at point A, gradually increases until the voltage at point A gradually approaches the reference voltage V REF When the current is changed, the voltage of the output end of the main operational amplifier is regulated, and the main operational amplifier can regulate the output of the G pole of the power tube M0, so that the output current I L Will not exceed the current limiting threshold I of the circuit LIMIT1 . Wherein I is LIMIT1 ＝K*V REF /R SET 。
However, with the output voltage V OUT Further decrease of input voltage V IN And output voltage V OUT And the difference of (2) continues to increase due to the output current I L Is always maintained at the current limiting threshold I LIMIT Chip power loss p=i LIMIT *(V IN -V OUT ) And the temperature of the chip junction is increased, so that the chip can be burnt. Some chips are also provided with an over-temperature protection circuit to protect the chip from being burned out, and the power path of the load is cut off when the chip temperature is too high. However, if the junction temperature of the chip is higher and higher, the threshold point of the over-temperature protection circuit in the chip is exceeded, so that the over-temperature protection circuit turns off a power path connected with the load, the load is powered down, and the normal operation of the equipment is affected.
That is, as shown in fig. 3, in the normal operation state of the chip, as the difference between the input voltage and the output voltage is larger, the output current is gradually increased. The current limiting protection circuit of the chip can maintain the output current unchanged when the output current increases to the current limiting threshold, namely the output current is unchanged after the chip enters the current limiting state.
However, after the chip is in a current-limiting state, as the difference between the input voltage and the output voltage is larger and larger, the power loss of the chip is larger and larger, and the junction temperature of the chip is higher and higher, so that the chip may be burnt or the load may be powered down.
In some examples, in order to solve the problem that the power loss of the chip is larger and the junction temperature of the chip is higher after the chip enters the current-limiting state, a current-limiting protection circuit capable of adjusting the current-limiting threshold value is further provided. After the chip enters a current limit state, the current limit threshold may be lowered so that the output current is also lowered. The output current of the chip is maintained at the reduced current limiting threshold value, so that even if the difference value between the input voltage and the output voltage is larger and larger, the power loss of the chip is not increased. The circuit can protect the chip from being damaged by the excessively high output current, and simultaneously effectively reduces the heating of the chip.
Illustratively, as shown in FIG. 4, FIG. 4 showsA current limiting protection circuit with an adjustable current limiting threshold is provided. The current-limiting protection circuit comprises a feedback control circuit, a clamping circuit and a power MOS tube M OUT Induction MOS tube M SNS A foldback resistor R FB Reference current source I SET 。M OUT Is a large-size power MOS tube, namely M OUT And M SNS The size ratio coefficient of (2) is M1, M is a larger positive number.
The structure of the clamp control circuit can refer to the connection of M2 and the clamp operational amplifier csamp in fig. 1. The feedback control circuit comprises a power MOS tube, and the G pole (connecting point 1) and M pole of the MOS tube OUT And M SNS G pole connection of (C). M is M SNS S pole connection R of (2) FB Is one end of M SNS The D pole of (c) is connected to the inductor current connection point 4 in the clamp control circuit. R is R FB Is connected with M at the other end OUT S pole of (2), input voltage V IN And a current source I SET Is provided. Current source I SET The output end of the (2) is connected with a mirror current connection point (3) in the clamp control circuit and a differential current delta I connection point (2) in the feedback control circuit. M is M OUT The D pole of (c) is connected to the output current connection point 5 in the clamp control circuit.
As can be seen from the above circuit structure, when M OUT Output current I of D pole of (2) OUT When gradually becoming larger, corresponding V OUT Descending. And because the clamp control circuit can maintain V SNS ＝V OUT And generate mirror current I SNS . When the mirror current I SNS Exceeding current source I SET Then, delta I is not zero, and the feedback control circuit is further caused to change M OUT The G-pole voltage Vg of (2) is further continuously adjusted to M OUT Current between S and D poles (source leakage current) to finally result in output current I OUT Will not continue to rise.
However, because of M OUT The chip can reach the current limiting threshold I faster LIMIT2 Wherein I LIMIT2 ＝(M+N)*I SET ，N＝R FB /R OUT ，R OUT Is M OUT Source-drain equivalent impedance in normal operating conditions. And with V OUT Further decrease of input voltage V IN And output voltage V OUT The difference of (c) continues to increase, M OUT Will enter the saturation region, the foldback resistor R FB Will cause the chip output current to be limited by a defined threshold I LIMIT2 Reduce to I LIMIT3 And constant current output is always maintained.
That is, as shown in FIG. 5, the chip is in a normal operation state along with the input voltage V IN And output voltage V OUT The difference is larger and larger, and the output current is gradually increased. After the output current reaches the current limiting threshold, the current limiting threshold is also regulated down through the foldback resistor, so that the output current of the chip is maintained at the reduced current limiting threshold. Furthermore, the circuit can protect the chip from being damaged by the excessively high output current, and simultaneously effectively reduce the heating of the chip.
However, in the current limiting protection circuit with foldback characteristics, the current limiting threshold after the decrease is also a fixed value. And, to prevent the input voltage V of the power path IN And output voltage V OUT The difference value of (2) is further increased to trigger an internal over-temperature protection circuit or burn out a chip, and the reduced current limiting threshold is usually lower, namely I LIMIT3 Lower values of (c) result in reduced chip carrying capacity.
On the other hand, some loads are provided with external switches which can adjust the current limiting threshold, so that the chip is applied in the scene of lower current limiting threshold, even if the input voltage V IN And output voltage V OUT The difference in (c) reaches a limit value, for example in the case of a short circuit, the chip will not burn out due to too high a power loss. Under the scene, the output current is reduced by reducing the current limiting threshold value, which is unfavorable for fully playing the chip carrying capacity and limits the applicable scenes of the chip.
In order to solve the problem that the chip junction temperature is reduced by reducing the current limiting threshold value to influence the chip carrying capacity, the application provides a temperature-based current limiting protection circuit which comprises a temperature adjusting unit, a feedback control unit and a power unit. The temperature adjusting unit is connected with the feedback control unit, and the feedback control unit is connected with the power unit. The temperature adjusting unit is used for generating a pull-down signal according to the current temperature, and the pull-down signal is used for adjusting the reference signal; the feedback control unit is used for comparing the reference signal with the sampling signal of the power unit to obtain a comparison result, and generating a control signal for adjusting the output signal according to the comparison result.
The circuit can also comprise a sampling unit and a reference voltage unit, wherein the sampling unit is connected with the power unit and the feedback control unit, and the reference voltage unit is connected with the temperature adjusting unit and the feedback control unit, and the sampling unit is used for collecting output signals of the power unit to obtain sampling signals; the reference voltage unit is used for determining the reference signal according to the pull-down signal.
The feedback control unit generates a control signal for adjusting the output signal according to the comparison result specifically includes: when the sampling signal does not reach the reference signal, the feedback control unit determines the control signal as a first control signal; when the sampling signal reaches the reference signal, the feedback control unit determines the control signal as a second control signal; the first control signal enables the output signal of the power unit to be smaller than a set threshold value, and the second control signal enables the output signal of the power unit to be equal to the set threshold value.
The temperature adjusting unit is used for generating a pull-down signal according to the current temperature, and specifically comprises the following steps: when the temperature reference signal does not reach the reference signal, the temperature adjusting unit determines the pull-down signal as a first pull-down signal; when the temperature reference signal reaches the reference signal, the temperature adjusting unit determines the pull-down signal as a second pull-down signal; the reference signal determined by the reference voltage unit according to the second pull-down signal is smaller than the reference signal determined by the reference voltage unit according to the first pull-down signal.
It should be appreciated that the pull-down signal may be a pull-down voltage or a pull-down current, the reference signal may be a reference voltage or a reference current, the output signal may be an output voltage or an output current, and the sampling signal may be a sampling voltage or a sampling current.
The following description will exemplify the pull-down signal as a pull-down current, the reference signal as a reference voltage, the output signal as an output current, and the sampling signal as a sampling current.
The temperature regulating unit can generate pull-down current with adjustable reference voltage according to the temperature of the chip, so as to regulate the current limiting threshold value. The feedback control unit is used for adjusting the output current of the power unit according to the reference voltage so that the output current is smaller than the current limiting threshold value.
Specifically, the feedback control unit obtains a corresponding sampling voltage according to a sampling current obtained by sampling the output current of the power tube, compares the sampling voltage with a reference voltage through the operational amplifier, adjusts the G-pole voltage of the power tube according to a comparison result, and then adjusts the output current of the power tube, so that the output current is stabilized at a current limiting threshold. Meanwhile, if the output current is unchanged, the input voltage V IN And output voltage V OUT The difference between the base (B pole) and the emitter (E pole) of the triode is increased, so that the junction temperature of the chip is increased, and the temperature regulating unit can also regulate the junction temperature by the voltage difference V between the base (B pole) and the emitter (E pole) of the triode BE The characteristic of negative correlation with temperature is used for generating pull-down current influencing the magnitude of the reference voltage, so that after the output current reaches the current limiting threshold value, the current limiting protection circuit can adjust the magnitude of the reference voltage only when the junction temperature of the chip is raised enough to enable the temperature adjusting unit to generate pull-down current, namely, the junction temperature of the chip reaches the temperature threshold value, and then the magnitude of the current limiting threshold value is adjusted.
Thus, the current limit threshold of the circuit is required to be lowered when the junction temperature of the chip is raised after the output current exceeds the current limit threshold. After the output current of the chip rises to the current limiting threshold, the output current can be kept constant within the current limiting threshold, and when the junction temperature rises to the temperature threshold, the output current can be reduced along with the reduction of the current limiting threshold.
The following describes the operation state of the temperature-based current limiting protection circuit provided in the present application with reference to fig. 6, where the operation state of the temperature-based current limiting protection circuit includes a normal operation state, a fixed current limiting state, and a foldback current limiting state as shown in fig. 6.
The normal working mode means that the output current of the power tube does not reach the current limiting threshold, the feedback control unit is not triggered to adjust the grid voltage of the power tube at the moment, the chip cannot enter the current limiting mode, and the feedback control unit inputs a first control signal to the G electrode of the power tube at the moment. Meanwhile, the junction temperature of the chip is insufficient to trigger the temperature adjusting unit to work, and the pull-down signal generated by the temperature adjusting unit is a first pull-down signal.
The fixed current-limiting working mode refers to that the output current of the power tube reaches a current-limiting threshold I LIMIT4 And triggering the feedback control unit to adjust the grid voltage of the power tube, wherein the feedback control unit inputs a second control signal to the G electrode of the power tube. However, the junction temperature of the chip is insufficient to trigger the temperature adjusting unit, the temperature adjusting unit will not generate a pull-down current, and the pull-down signal generated by the temperature adjusting unit is the first pull-down signal, so that the output current is maintained at the current limiting threshold I LIMIT4 A kind of electronic device.
The foldback current limiting mode refers to the power path current reaching the current limiting threshold, and then following the input voltage V IN And output voltage V OUT The difference of (2) is further increased, and the junction temperature of the chip is increased to trigger the temperature regulating unit to work. At this time, the temperature adjusting unit adjusts the reference voltage through the triode, and then the current limiting threshold will be reduced, so that the power loss of the chip is approximately constant, and the junction temperature of the chip is in an equilibrium state. At this time, the feedback control unit inputs a second control signal to the G pole of the power tube, and the pull-down signal generated by the temperature adjusting unit is the second pull-down signal.
The description of the temperature-based current limiting protection circuit in each operating state will be further described in detail below in connection with the circuit connection of the temperature-based current limiting protection circuit, and will not be repeated here.
In summary, the temperature-based current limiting protection circuit provided by the application can prevent the risk of load power failure caused by triggering over-temperature protection in a current limiting state. After the scheme enters the current limiting state, the current limiting threshold value is not triggered to turn back immediately, the output current capacity is not reduced, and the application scene of the chip is greatly widened. The current limiting threshold value is further reduced along with the increase of the input-output voltage difference, so that the junction temperature of the chip is reduced, and the chip can work in a current limiting state for a long time without being burnt by power consumption generated by current limiting.
The structure of the temperature-based current limiting protection circuit provided in the present application is described below. As shown in fig. 7, the temperature-based current limiting protection circuit includes a sampling unit, a temperature adjusting unit, a feedback control unit, a reference voltage unit, a power unit and a load unit.
The power unit comprises a power tube, and the power tube is connected with the load unit. The sampling unit is used for collecting the output current of the power tube in the power unit and transmitting the sampled current to the feedback control module. The temperature regulating unit can generate pull-down current with adjustable reference voltage according to the temperature of the chip. The reference voltage unit determines the magnitude of the reference voltage according to the pull-down current and the reference voltage. The feedback control unit is used for comparing the reference voltage with the voltage corresponding to the sampling current, and adjusting the G pole voltage of the power tube according to the comparison result, so as to adjust the output current of the circuit.
A specific circuit diagram of the above-described temperature-based current limiting protection circuit is described below with reference to fig. 8.
The power unit comprises a power tube M0, the sampling unit comprises a sampling tube M1, the size proportionality coefficient of the power tube M0 and the sampling tube M1 is K1, and thus, the sampling tube M1 samples the obtained current I SET ＝I L and/K. The load unit comprises a resistor R L And capacitor C L The feedback control unit comprises a MOS tube M2 and a resistor R SET The system comprises an operational amplifier csamp and a main_amp, wherein the csamp is a clamping operational amplifier, and the main_amp is a current limiting and regulating main operational amplifier. The negative input terminal except main_amp is connected with reference voltage V REF_OC In addition, the connection of the power unit, the sampling unit, the load unit and the feedback control unit may refer to fig. 1 and the related description thereof, and will not be repeated here.
The reference voltage unit comprises an operational amplifier buf_amp, a MOS tube M2 and resistors R1 and R2. The temperature regulating unit comprises an operational amplifier temp_amp, a triode Q1 and a current source I B MOS tube M3.
The negative input end of the buf_amp in the reference voltage unit is connected with the reference voltage V REF And a positive input terminal of temp_amp, the positive input terminal is connected with D pole of M2 and one end of R1, the output terminal is connected with G pole of M2, and the positive power supply terminal is connected with input voltage V IN And an S pole of M2. The other end of R1 is connected with one end of R2, the D pole of M3 and the negative output end of main_amp, and the other end of R2 is grounded.
Current source I in temperature regulating unit B Is connected with an input voltage V IN The output terminal is connected to the negative input terminals of the B pole, collector (collecting electrode, C pole) and temp_amp of transistor Q1. The E pole of the triode Q1 is grounded. the output terminal of temp_amp is connected to the G pole of M3, and the S pole of M3 is grounded.
It should be understood that fig. 8 is only one implementation of the temperature-based current limiting protection circuit, and in other embodiments, the temperature adjustment unit may also add a plurality of transistors to ensure accuracy of temperature detection. Alternatively, in other embodiments, other devices may be used in the temperature regulating unit, such as devices where the output signal is positively correlated to temperature. Alternatively, in other embodiments, the output tube voltage may be sampled. The specific structure and components of the circuit are not particularly limited in this application.
The following describes in detail the operation state of the temperature-based current limiting protection circuit provided in the present application with reference to fig. 6 to 8.
(1) Normal mode of operation
When the input voltage V IN And output voltage V OUT The difference value of the output current I of the power tube M0 is larger and larger L And gradually increases. When the output current I of the power tube M0 L When the current limiting threshold is not reached yet, sampling current I acquired by sampling tube M1 in the sampling unit SET Smaller, where I SET ＝I L and/K. And then sample the current I SET Through resistor R SET Voltage V generated at point A A Smaller, where V A ＝R SET *I SET . So that the reference voltage V of the negative input end in main_amp in the feedback control unit REF_OC Always greater than V A Wherein V is REF_OC ＝V REF * R2/(R1+R2). At this time, main_amp in the feedback control unit is not triggered to adjust the G pole voltage of the power tube M0.
In addition, the junction temperature of the chip is not high at this time, so that the voltage difference output by the triodeV BE Always greater than reference voltage V REF . Thus the pull-down voltage V of temp_amp operational amplifier output pull Always at lower potential, the pull-down tube M3 is not activated, and the pull-down current I in the temperature regulating unit pull Always zero. The reference voltage is a constant value in this state and the current limit threshold is also a constant value.
(2) Fixed current limiting state
When the input voltage V IN And output voltage V OUT The difference of the output current I of the power tube M0 is further increased L Reaching the current limiting threshold I LIMIT4 When I LIMIT4 ＝K*V REF_OC /R SET Sampling current I collected by sampling tube M1 in sampling unit SET Reach V REF_OC /R SET . Sampling current I SET Through resistor R SET Voltage V generated at point A A Reaching the reference voltage V of the negative input end of main_amp in the feedback control unit REF_OC Thereby triggering main_amp in the feedback control unit to regulate the grid voltage of the power tube M0, so that the output current I of the power tube M0 L Stabilized at I LIMIT4 。
With input voltage V IN And output voltage V OUT Further increase in difference in chip power loss p=i LIMIT4 *(V IN -V OUT ) With a consequent increase in the junction temperature of the chip. But if the current limiting threshold I is set LIMIT4 At lower level, even V IN And V OUT The pressure difference reaching a limit (e.g. V OUT Short to ground), chip junction temperature ψ J ＝ψ T +ψ JA * P is not too high, wherein ψ T For the ambient temperature, ψ, of the chip during operation JA The thermal resistance of the die to the surrounding environment for a particular package form.
At this time, the junction temperature of the chip is not high, so that the voltage difference V output by the triode BE Always greater than reference voltage V REF . Thus the pull-down voltage V of temp_amp op-amp pull Is always at lower potential, does not activate the pull-down tube M3, and pulls down the current I in the temperature regulating unit pull Always zero. The reference voltage is constant in this state, the current is limitedThe threshold value is also constant, and the current I is output L And thus also a constant value.
(3) Foldback current limiting state
When the input voltage V IN And output voltage V OUT The difference of (2) continues to increase since the output current is constant at I at this time LIMIT4 Chip power loss p=i LIMIT4 *(V IN -V OUT ) With a consequent increase in the junction temperature of the chip. But if the current limiting threshold I is set LIMIT4 At higher chip junction temperature ψ J ＝ψ T +ψ JA * P will be higher, wherein ψ T For the ambient temperature, ψ, of the chip during operation JA The thermal resistance of the die to the surrounding environment for a particular package form.
If the junction temperature of the chip increases, the current I flowing through the triode B Fixed, triode V BE The voltage decreases with increasing temperature, so that the negative input terminal V of the operational amplifier temp_amp in the temperature regulating unit BE Reaching the reference voltage V of the positive input end REF The reference voltage V REF The output voltage V of temp_amp operation amplifier does not change with temperature pull Will rise to the activation of pull-down tube M3, pull-down branch current I in the temperature regulating unit pull Flows through R1 in the voltage dividing resistor string in the reference voltage unit to enable the reference voltage V at the reverse end of the main_amp of the operational amplifier REF_OC And (3) lowering.
At this time V REF_OC ＝(V REF *R2-I pull * R2)/(R1+R2), and the current limit threshold becomes I LIMIT5 ＝K*V REF_OC /R SET ＝K*(V REF *R2-I pull *R2)/[(R1+R2)*R SET ]. Wherein I is pull ＝G m *(V REF -V BE )，G m The transconductance of the operational amplifier temp_amp in the temperature regulating unit.
Thus, the input voltage V IN And output voltage V OUT The larger the difference value of the transistor V, the higher the junction temperature of the chip BE The lower the voltage, the lower the pull-down branch current I in the temperature regulating unit pull The larger the reverse end reference voltage V of the operational amplifier main_amp REF_OC Lower the chip internal current limit I LIMIT5 Return to a lower current limit value so that the chip power loss p=i LIMIT5 *(V IN -V OUT ) Approximately constant, chip junction temperature ψ J ＝ψ T +ψ JA * P is in an equilibrium state and is set so that it is always below the internal over-temperature protection threshold point.
In summary, the temperature-based current limiting protection circuit provided by the application can prevent the risk of load power failure caused by triggering over-temperature protection in a current limiting state. In addition, after the current limiting protection circuit enters a current limiting state, the current limiting threshold value is not triggered to turn back immediately, the output current capacity is not reduced, and the application scene of the chip is greatly widened. The current limiting threshold value is further reduced along with the increase of the input-output voltage difference, so that the junction temperature of the chip is reduced, and the chip can work in a current limiting state for a long time without being burnt by power consumption generated by current limiting.
On the other hand, the embodiment of the invention also provides a chip, which is formed with the temperature-based current limiting protection circuit in any embodiment. The chip may be an analog-to-digital conversion chip, an interface chip or a power management chip.
On the other hand, the embodiment of the invention also provides electronic equipment, which can comprise the chip. The electronic device may be a cell phone, tablet, wearable device, vehicle-mounted device, notebook, ultra mobile personal computer, netbook or specialized camera (e.g., single-lens reflex, card-type camera), etc.
In the present specification, each embodiment is described in a progressive manner, or a parallel manner, or a combination of progressive and parallel manners, and each embodiment is mainly described as a difference from other embodiments, and identical and similar parts between the embodiments are all enough to refer to each other.
It should be noted that, in the description of the present invention, it should be understood that the directions or positional relationships indicated by the terms "upper", "lower", "top", "bottom", "inner", "outer", etc. are based on the directions or positional relationships shown in the drawings, are merely for convenience of describing the present invention and simplifying the description, and do not indicate or imply that the devices or elements to be referred to must have a specific orientation, be configured and operated in a specific orientation, and thus should not be construed as limiting the present invention. When an element is referred to as being "connected" to another element, it can be directly connected to the other element or intervening elements may also be present.
It is further noted that relational terms such as first and second, and the like are used solely to distinguish one entity or action from another entity or action without necessarily requiring or implying any actual such relationship or order between such entities or actions. Moreover, the terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that an article or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such article or apparatus. Without further limitation, an element defined by the phrase "comprising one … …" does not exclude the presence of other like elements in an article or apparatus that comprises such element.
The previous description of the disclosed embodiments is provided to enable any person skilled in the art to make or use the present application. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to other embodiments without departing from the spirit or scope of the application. Thus, the present application is not intended to be limited to the embodiments shown herein but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims (11)

1. A temperature-based current limiting protection circuit is characterized by comprising a feedback control unit, a reference voltage unit, a temperature regulating unit and a power unit, wherein,
the temperature adjusting unit is used for generating a pull-down signal according to the current temperature;
the reference voltage unit is used for determining a reference signal according to the pull-down signal;
the feedback control unit is used for comparing the reference signal with a sampling signal of the power unit and determining a control signal of the power unit according to a comparison result;
the power unit is used for determining an output signal according to the control signal.
2. The temperature-based current limiting protection circuit of claim 1, further comprising a sampling unit, wherein,
the sampling unit is used for collecting the output signal of the power unit so as to obtain the sampling signal.
3. The temperature-based current limiting protection circuit of claim 1, wherein the feedback control unit is configured to compare the reference signal with a sampling signal of the power unit, and determine a control signal for the power unit according to the comparison result, comprising:
the feedback control unit is used for comparing the reference signal with the sampling signal, and when the sampling signal does not reach the reference signal, the feedback control unit determines the control signal as a first control signal; when the sampling signal reaches the reference signal, the feedback control unit determines the control signal as a second control signal; the first control signal enables the output signal of the power unit to be smaller than a set threshold value, and the second control signal enables the output signal of the power unit to be equal to the set threshold value.
4. The temperature-based current limiting protection circuit of claim 1, wherein the temperature adjustment unit is configured to generate a pull-down signal according to temperature, comprising:
the temperature regulating unit is used for generating a temperature reference signal according to the temperature;
the temperature regulating unit is further used for determining the pull-down signal according to the temperature reference signal and the reference signal, wherein the pull-down signal is used for indicating whether the temperature reference signal reaches the reference signal or not.
5. The temperature-based current limiting protection circuit of claim 4, wherein,
when the temperature reference signal does not reach the reference signal, the temperature adjustment unit determines the pull-down signal as a first pull-down signal; when the temperature reference signal reaches the reference signal, the temperature adjusting unit determines the pull-down signal as a second pull-down signal;
the reference signal determined by the reference voltage unit according to the second pull-down signal is smaller than the reference signal determined by the reference voltage unit according to the first pull-down signal.
6. The temperature-based current limiting protection circuit of claim 5, wherein,
the temperature regulating unit comprises a temperature acquisition element which is used for generating the temperature reference signal, wherein the temperature reference signal is positively or negatively related with the current temperature.
7. The temperature-based current limiting protection circuit of claim 6, wherein,
the temperature acquisition element is one or more triodes.
8. The temperature-based current limiting protection circuit of claim 7, wherein the temperature adjustment unit further comprises an operational amplifier for determining the pull-down signal based on the temperature reference signal and the reference signal.
9. The temperature-based current limiting protection circuit of claim 8, wherein,
the temperature adjustment unit is further configured to determine that the pull-down signal is not zero based on the sampling signal reaching the reference signal and the temperature reference signal reaching the reference signal.
10. A chip having the temperature-based current limiting protection circuit of any one of claims 1-9 formed therein.
11. An electronic device comprising a chip having the temperature-based current limiting protection circuit of any one of claims 1-9 formed therein.
CN202310086237.5A 2023-02-01 2023-02-01 Current-limiting protection circuit, chip and electronic equipment based on temperature Pending CN116048178A (en)

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Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN116578154A (en) * 2023-06-13 2023-08-11 陕西四方华能电气设备有限公司 Automatic voltage tracking method and system for voltage regulator
CN116707290A (en) * 2023-08-08 2023-09-05 如果新能源科技(江苏)股份有限公司 Over-temperature protection method for power conversion device and power conversion device

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN116578154A (en) * 2023-06-13 2023-08-11 陕西四方华能电气设备有限公司 Automatic voltage tracking method and system for voltage regulator
CN116578154B (en) * 2023-06-13 2023-11-21 陕西四方华能电气设备有限公司 Automatic voltage tracking method and system for voltage regulator
CN116707290A (en) * 2023-08-08 2023-09-05 如果新能源科技(江苏)股份有限公司 Over-temperature protection method for power conversion device and power conversion device
CN116707290B (en) * 2023-08-08 2023-12-01 如果新能源科技(江苏)股份有限公司 Over-temperature protection method for power conversion device and power conversion device

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