A temperature-based current limiting protection circuit, chip and electronic device

Abstract

The present application is applied to the field of integrated circuit technology, and provides a temperature-based current limiting protection circuit, chip and electronic device, wherein the circuit includes a feedback control unit, a reference voltage unit, a temperature adjustment unit and a power unit, the temperature adjustment unit is used to generate a pull-down signal according to the current temperature; the reference voltage unit is used to determine the reference signal according to the pull-down signal; the feedback control unit is used to compare the reference signal with the sampling signal of the power unit, and determine the control signal of the power unit according to the comparison result; the power unit is used to determine the output signal according to the control signal. In this way, after entering the current limiting state, the current limiting threshold value will not be triggered immediately, and the output current capacity will not be reduced. As the input-output voltage difference increases, the current limiting threshold value will be further reduced, thereby reducing the chip junction temperature, so that the circuit or chip can work in the current limiting state for a long time without being burned by the power consumption generated by the current limiting.

Description

Technical Field

[0001] The present invention relates to the technical field of integrated circuits, and in particular to a temperature-based current limiting protection circuit, a chip and an electronic device. Background Art

[0002] In order to protect the chip from being burned out due to excessive current when the load is increased instantly or a short circuit occurs, a current limiting protection circuit is added to the chip. The current limiting protection circuit usually samples the output current / voltage in the chip output circuit, compares the sampled output current / voltage with the reference current / voltage, and then limits the output current of the output circuit based on the comparison result.

[0003] However, the reference current / voltage of the current limiting protection circuit is currently a fixed value, that is, the current limiting threshold is a fixed value. As a result, when the current limiting protection circuit is in the current limiting state, the output current of the chip remains unchanged, but as the difference between the input voltage and the output voltage increases, the chip power loss also increases, which will cause the chip junction temperature to become higher and higher. Most chips are also equipped with an over-temperature protection circuit, which will cut off the power path of the load when the chip temperature is too high. If the chip junction temperature becomes higher and higher and exceeds the threshold point of the over-temperature protection circuit in the chip, the over-temperature protection circuit will shut down the power path connected to the load, causing the load to lose power and affecting the normal operation of the equipment. Summary of the invention

[0004] The present application provides a temperature-based current limiting protection circuit, chip, and electronic device, which can not immediately trigger the current limiting threshold foldback after entering the current limiting state, and will not cause the output current capacity to decrease. As the input-output voltage difference increases, the current limiting threshold will be further reduced, thereby reducing the junction temperature, so that the circuit or chip can work in the current limiting state for a long time without being burned by the power consumption generated by the current limiting.

[0005] In a first aspect, a temperature-based current limiting protection circuit is provided, which includes a feedback control unit, a reference voltage unit, a temperature adjustment unit and a power unit, wherein the temperature adjustment unit is used to generate a pull-down signal according to the current temperature; the reference voltage unit is used to determine a reference signal according to the pull-down signal; the feedback control unit is used 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; the power unit is used to determine an output signal according to the control signal.

[0006] In the above scheme, the pull-down signal can be a pull-down voltage or a pull-down current, the reference signal can be a reference voltage or a reference current, the output signal can be an output voltage or an output current, and the sampling signal can be a sampling voltage or a sampling current. The circuit can adjust the reference voltage according to the temperature, and then adjust the current limiting threshold, so that after entering the current limiting state, the current limiting threshold will be lowered after the chip temperature reaches the junction temperature, so that the circuit or chip can work in the current limiting state for a long time without being burned by the power consumption generated by the current limiting.

[0007] In combination with the first aspect, in some implementations, the circuit further includes a sampling unit, wherein the sampling unit is used to collect an output signal of the power unit to obtain a sampling signal.

[0008] In combination with the first aspect, in some implementations, the feedback control unit is used to compare a 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 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; wherein the first control signal makes the output signal of the power unit less than a set threshold, and the second control signal makes the output signal of the power unit equal to the set threshold.

[0009] In combination with the first aspect, in some implementations, the temperature adjustment unit is used to generate a temperature reference signal according to the temperature; the temperature adjustment unit is also used to determine a pull-down signal according to the temperature reference signal and a reference signal, and the pull-down signal is used to indicate whether the temperature reference signal reaches the reference signal.

[0010] In combination with the first aspect, in some implementations, when the temperature reference signal does not reach the reference 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 adjustment unit determines the pull-down signal as the second pull-down signal; wherein the reference signal determined by the reference voltage unit based on the second pull-down signal is less than the reference signal determined by the reference voltage unit based on the first pull-down signal.

[0011] In combination with the first aspect, in some implementations, the temperature adjustment unit includes a temperature acquisition element, the temperature acquisition element is used to generate a temperature reference signal, and the temperature reference signal is positively correlated or negatively correlated with the current temperature.

[0012] In combination with the first aspect, in some implementations, the temperature collection element is one or more transistors.

[0013] In combination with the first aspect, in some implementations, the temperature adjustment unit further includes an operational amplifier, and the operational amplifier is used to determine the pull-down signal according to the temperature reference signal and the reference signal.

[0014] In combination with the first aspect, in some implementations, based on the sampling signal reaching the reference signal and the temperature reference signal reaching the base signal, the temperature adjustment unit is further configured to determine that the pull-down signal is not zero.

[0015] In a second aspect, a chip is provided, in which a temperature-based current limiting protection circuit as described in any one of the first aspects is formed.

[0016] According to a third aspect, an electronic device is provided, the electronic device comprising a chip, wherein the temperature-based current limiting protection circuit as described in any one of the first aspects is formed in the chip. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the following briefly introduces the drawings required for describing the embodiments.

[0018] Figure 1 It is a circuit diagram of a current limiting protection circuit with a fixed current limiting threshold provided in an embodiment of the present application;

[0019] Figure 2 is a schematic diagram of the structure of a field effect transistor provided in an embodiment of the present application;

[0020] Figure 3 It is a schematic diagram of an output current curve of a current limiting protection circuit with a fixed current limiting threshold provided in an embodiment of the present application;

[0021] Figure 4 It is a circuit diagram of a current limiting protection circuit provided in an embodiment of the present application, in which the current limiting threshold is reduced after the output current reaches the current limiting threshold;

[0022] Figure 5 It is a curve diagram showing a decrease in a current limiting threshold of a current limiting protection circuit provided in an embodiment of the present application after the output current reaches the current limiting threshold;

[0023] Figure 6 is a curve diagram of an output current of a temperature-based current limiting protection circuit provided in an embodiment of the present application;

[0024] Figure 7 is a schematic diagram of a structure of a temperature-based current limiting protection circuit provided in an embodiment of the present application;

[0025] Figure 8 This is a circuit diagram of a temperature-based current limiting protection circuit provided in an embodiment of the present application. DETAILED DESCRIPTION

[0026] The illustrative embodiments of the present application include, but are not limited to, a temperature-based current limiting protection circuit, a chip, and an electronic device.

[0027] In order to protect the chip from being burned out due to excessive current when the load increases suddenly or a short circuit occurs, a current limiting protection circuit is added to the chip, such as an operational amplifier output short-circuit current limiting circuit, a low-dropout linear regulator, etc. In order to avoid the chip being damaged due to a sudden increase in the current in the chip due to a sudden decrease in the circuit load, or a short circuit at the output of the chip, a current limiting protection circuit needs to be integrated inside the chip. The function of the current limiting protection circuit is that when the current on the protected device exceeds the set current limiting threshold, it will enter the current limiting state and limit the output current of the power tube to the current limiting threshold. When the output current of the power tube gradually decreases, the system automatically returns to normal working state, thereby protecting the chip.

[0028] For example, Figure 1 As shown, Figure 1 The circuit diagram of a current limiting protection circuit with a fixed current limiting threshold is shown. The current limiting protection circuit includes metal-oxide-semiconductor field-effect transistors (MOSFET, MOS tube for short) M0, M1 and M2, operational amplifiers (operational amplifier, OP amp for short) csamp and main_amp, resistor R SET , R L , capacitor C L Among them, M0 is an output tube, that is, a power tube, specifically an N-channel MOS tube (negative channel MOS, NMOS tube) in a MOS tube. The structure of the NMOS tube is as follows Figure 2 As shown by Figure 2 It can be seen that the NMOS tube includes a drain (drain pole, D pole), a gate (G pole) and a source (S pole). M1 is a sampling tube, specifically also an NMOS tube. The size ratio coefficient of the power tube M0 and the sampling tube M1 is K:1. csamp is a clamping op amp, and main_amp is a current limiting regulation main op amp.

[0029] The power supply terminal of the current limiting regulator main op amp main_amp is connected to the input voltage V IN , the negative input terminal is connected to the reference voltage V REF , the positive input terminal and the D pole of M2 are connected with a resistor R SET One end of the resistor R SET The other end of the main_amp is connected to the G pole of the power tube M0 and the sampling tube M1. The S pole of the power tube M0 and the sampling tube M1 is connected to the input voltage V IN , the D pole of the power tube M0 is connected to the positive input terminal of the clamping amplifier csamp, the resistor R L One end of the capacitor CL One end and the output voltage V OUT . Resistance R L The other end and capacitor C L The other end is grounded. The D pole of the sampling tube M1 is connected to the negative input terminal of the clamping amplifier csamp and the S pole of M2. The G pole of M2 is connected to the output terminal of the clamping amplifier csamp.

[0030] From the above circuit structure, it can be seen that the D-pole current of M0 is the output current I L , the output current is connected to the positive input of the clamp op amp csamp and the resistor R L , capacitor C L The corresponding output voltage is V OUT M0 is a power tube, and the circuit part where it is located is the power path. When the input voltage V IN and output voltage V OUT When the difference increases, the output current I L The clamping op amp csamp and M2 can make the D-pole voltage of M0 and M1 equal. When the size ratio coefficient of M0 and M1 is K:1, the sampling current I SET Also increases proportionally, among which, I SET =I L / K. Then, the resistance R SET The upper voltage, that is, the voltage at point A, gradually increases until the voltage at point A gradually approaches the reference voltage V REF When the current limiting regulator is on, it will cause the voltage change of the output terminal of the main operational amplifier main_amp, and then main_amp can regulate the output of the G pole of the power tube M0, so that the output current I L The circuit's current limit threshold I LIMIT1 Among them, I LIMIT1 =K*V REF / R SET .

[0031] However, as the output voltage V OUT Further reducing the input voltage V IN and output voltage V OUT The difference continues to increase, due to the output current I L Maintained at the current limiting threshold I LIMIT The size of the chip power loss P = I LIMIT *(V IN -V OUT) will also increase, making the chip junction temperature higher and higher, which may burn the chip. In order to protect the chip from being burned, some chips are also equipped with over-temperature protection circuits, which will cut off the power path of the load when the chip temperature is too high. However, if the chip junction temperature gets higher and higher and exceeds the threshold point of the over-temperature protection circuit in the chip, the over-temperature protection circuit will shut off the power path connected to the load, causing the load to lose power, which will affect the normal operation of the device.

[0032] That is to say, if Figure 3 As shown in the figure, when the chip is in normal working state, as the difference between the input voltage and the output voltage increases, the output current will gradually increase. The current limiting protection circuit of the chip can maintain the output current unchanged when the output current increases to the current limiting threshold, that is, the output current of the chip remains unchanged after entering the current limiting state.

[0033] However, after the chip enters the current limiting state, as the difference between the input voltage and the output voltage becomes larger and larger, the chip power loss becomes larger and larger, and the chip junction temperature becomes higher and higher, which may burn the chip or cause the load to lose power.

[0034] In some examples, in order to solve the problem that the chip power loss is getting bigger and bigger and the chip junction temperature is getting higher and higher after the chip enters the current limiting state, a current limiting protection circuit with an adjustable current limiting threshold is also provided. After the chip enters the current limiting state, the current limiting threshold can be lowered so that the output current is also reduced. The output current of the chip is maintained at the lowered current limiting threshold, and then even if the difference between the input voltage and the output voltage becomes larger and larger, the chip power loss will not increase. This circuit can protect the chip from being damaged by excessive output current, while effectively reducing chip heating.

[0035] For example, Figure 4 As shown, Figure 4 A current limiting protection circuit with an adjustable current limiting threshold is shown. The current limiting protection circuit includes a feedback control circuit, a clamping circuit, and a power MOS tube M OUT , Induction MOS tube M SNS , foldback resistor R FB And the reference current source I SET . M OUT It is a large-size power MOS tube, namely M OUT and M SNS The size ratio coefficient is M:1, where M is a large positive number.

[0036] The structure of the clamp control circuit can be referred to Figure 1 The feedback control circuit includes a power MOS tube, the G pole (connection point 1) of the MOS tube is connected to M OUT and M SNS The G pole is connected to the M SNS The S pole is connected to RFB One end, M SNS The D pole is connected to the inductive current connection point 4 in the clamp control circuit. FB The other end is connected to M OUT S pole, input voltage V IN and current source I SET The current source I SET The output end of M is connected to the mirror current connection point 3 in the clamp control circuit and the difference current ΔI connection point 2 in the feedback control circuit. OUT The D pole is connected to the output current connection point 5 in the clamp control circuit.

[0037] From the above circuit structure, it can be seen that when M OUT The output current I of the D pole OUT As it gradually increases, the corresponding V OUT Drop. And because the clamp control circuit will keep V SNS =V OUT , and generates a mirror current I SNS When the mirror current I SNS Exceeding the current source I SET After that, △I is not zero, which prompts the feedback control circuit to change M OUT The G pole voltage Vg is then continuously adjusted OUT The current between the S and D poles (source-drain current) eventually makes the output current I OUT It will not continue to rise.

[0038] However, because M OUT The chip can reach the current limit threshold I faster because of its larger size. LIMIT2 , where I LIMIT2 =(M+N)*I SET , N=R FB / R OUT , R OUT M OUT The source-drain equivalent impedance in normal working state. OUT Further reducing the input voltage V IN and output voltage V OUT The difference continues to increase, M OUT It will enter the saturation region, and the return resistance R FB The chip output current will be limited by the threshold I LIMIT2 Reduce to I LIMIT3 , and maintain constant current output.

[0039] That is to say, if Figure 5 As shown, the chip is in normal working condition, as the input voltage V IN and output voltage V OUTAs the difference gets bigger, the output current will also gradually increase. After the output current reaches the current limit threshold, the current limit threshold will be lowered through the foldback resistor, so that the output current of the chip is maintained at the lowered current limit threshold. In turn, this circuit can protect the chip from being damaged by excessive output current and effectively reduce chip heating.

[0040] However, the current limiting threshold of the above-mentioned current limiting protection circuit with foldback characteristics is also a fixed value after being reduced. In addition, in order to prevent the input voltage V IN and output voltage V OUT The difference between the current limit and the current limit of the chip increases further, triggering the internal over-temperature protection circuit or burning the chip. The lowered current limit threshold is often lower, that is, I LIMIT3 The value is low, which reduces the chip's load capacity.

[0041] On the other hand, some loads have external switches with adjustable current limit thresholds. Therefore, when this chip is used in scenarios with lower current limit thresholds, even if the input voltage V IN and output voltage V OUT When the difference reaches the limit value, for example, in the case of a short circuit, the chip will not burn out due to excessive power loss. In this scenario, lowering the output current by lowering the current limiting threshold is not conducive to fully utilizing the chip's load capacity and limits the chip's applicable scenarios.

[0042] In order to solve the problem that lowering the chip junction temperature by lowering the current limiting threshold will affect the chip load capacity, the present application provides a temperature-based current limiting protection circuit, which includes a temperature adjustment unit, a feedback control unit and a power unit. The temperature adjustment unit is connected to the feedback control unit, and the feedback control unit is connected to the power unit. Among them, the temperature adjustment unit is used to generate a pull-down signal according to the current temperature, and the pull-down signal is used to adjust the reference signal; the feedback control unit is used to compare the reference signal with the sampling signal of the power unit to obtain a comparison result, and according to the comparison result, generate a control signal for adjusting the output signal.

[0043] The circuit may also include a sampling unit and a reference voltage unit, the sampling unit is connected to the power unit and the feedback control unit, and the reference voltage unit is connected to the temperature adjustment unit and the feedback control unit, wherein the sampling unit is used to collect the output signal of the power unit to obtain a sampling signal; and the reference voltage unit is used to determine the reference signal according to the pull-down signal.

[0044] The feedback control unit generates a control signal for adjusting the output signal based on the comparison result, specifically including: 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; wherein the first control signal makes the output signal of the power unit less than a set threshold, and the second control signal makes the output signal of the power unit equal to the set threshold.

[0045] The temperature adjustment unit is used to generate a pull-down signal according to the current temperature, specifically including: 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 adjustment unit determines the pull-down signal as a second pull-down signal; wherein the reference signal determined by the reference voltage unit according to the second pull-down signal is less than the reference signal determined by the reference voltage unit according to the first pull-down signal.

[0046] It should be understood 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.

[0047] The following example takes the pull-down signal as the pull-down current, the reference signal as the reference voltage, the output signal as the output current, and the sampling signal as the sampling current as an example.

[0048] The temperature adjustment unit can generate a pull-down current with an adjustable reference voltage according to the chip temperature, thereby adjusting the current limiting threshold. The feedback control unit is used to adjust the output current of the power unit according to the reference voltage so that the output current is less than the current limiting threshold.

[0049] Specifically, the feedback control unit obtains the corresponding sampling voltage based on the sampling current obtained by sampling the output current of the power tube, and then compares the sampling voltage with the reference voltage through the operational amplifier, and adjusts the G pole voltage of the power tube according to the comparison result, thereby adjusting the output current of the power tube so that the output current is stable at the current limiting threshold. At the same time, if the output current remains unchanged, the input voltage V IN and output voltage V OUT The difference is further increased, causing the chip junction temperature to rise. The temperature adjustment unit also passes through the voltage difference V between the base (base, B pole) and the emitter (emitter, E pole) of the transistor. BE The characteristic of being negatively correlated with temperature is used to generate a pull-down current that affects the size of the reference voltage, so that after the output current reaches the current limiting threshold, the current limiting protection circuit will adjust the size of the reference voltage and then adjust the size of the current limiting threshold only when the chip junction temperature rises to a level sufficient to cause the temperature adjustment unit to generate a pull-down current, that is, when the chip junction temperature reaches the temperature threshold.

[0050] In this way, after the output current of the circuit exceeds the current limit threshold, the current limit threshold of the circuit will decrease when the junction temperature of the chip rises. After the output current of the chip rises to the current limit threshold, it can be stabilized within the current limit threshold first, and when the junction temperature rises to the temperature threshold, the output current will decrease as the current limit threshold decreases.

[0051] Combine the following Figure 6 The working state of the temperature-based current limiting protection circuit provided by this application is introduced, such as Figure 6 The working states of the temperature-based current limiting protection circuit include a normal working state, a fixed current limiting state, and a foldback current limiting state.

[0052] Normal working mode means that the output current of the power tube does not reach the current limiting threshold. At this time, the feedback control unit will not be triggered to adjust the gate voltage of the power tube, and the chip will not enter the current limiting mode. At this time, the feedback control unit inputs the first control signal to the G pole of the power tube. At the same time, the chip junction temperature is not enough to trigger the temperature adjustment unit to work. At this time, the pull-down signal generated by the temperature adjustment unit is the first pull-down signal.

[0053] Fixed current limiting mode means that the output current of the power tube reaches the current limiting threshold I LIMIT4 , and the feedback control unit is triggered to adjust the gate voltage of the power tube. At this time, the feedback control unit inputs the second control signal to the G pole of the power tube. However, the chip junction temperature is not enough to trigger the temperature adjustment unit, and the temperature adjustment unit will not generate a pull-down current. At this time, the pull-down signal generated by the temperature adjustment unit is the first pull-down signal, so that the output current is maintained at the current limiting threshold I LIMIT4 of.

[0054] The foldback current limiting mode means that after the power path current reaches the current limit threshold, the input voltage V IN and output voltage V OUT The difference further increases, and the junction temperature of the chip rises to trigger the temperature adjustment unit to work. At this time, the temperature adjustment unit will adjust the reference voltage through the transistor, and then the current limiting threshold will decrease, so that the chip power loss is approximately constant and the chip junction temperature is in a balanced state. At this time, the feedback control unit inputs the second control signal to the G pole of the power tube, and the pull-down signal generated by the temperature adjustment unit is the second pull-down signal.

[0055] The description of the temperature-based current limiting protection circuit in each working state will be described in detail later in conjunction with the circuit connection of the temperature-based current limiting protection circuit, which will not be repeated here.

[0056] In summary, the temperature-based current limiting protection circuit provided by the present application can prevent the risk of load power failure caused by triggering over-temperature protection in the current limiting state. After entering the current limiting state, this solution will not immediately trigger the current limiting threshold foldback, will not cause the output current capacity to decrease, and will greatly broaden the chip application scenarios. As the input-output voltage difference increases, the current limiting threshold will be further reduced, thereby reducing the chip junction temperature, so that the chip can work in the current limiting state for a long time without being burned by the power consumption generated by the current limiting.

[0057] The structure of the temperature-based current limiting protection circuit provided by the present application is introduced below. Figure 7 As shown, the temperature-based current limiting protection circuit includes a sampling unit, a temperature adjustment unit, a feedback control unit, a reference voltage unit, a power unit and a load unit.

[0058] Among them, the power unit includes a power tube, and the power tube is connected to the load unit. The sampling unit is used to collect the output current of the power tube in the power unit and transmit the sampled current to the feedback control module. The temperature adjustment unit can generate a pull-down current with an adjustable reference voltage according to the chip temperature. The reference voltage unit determines the reference voltage according to the pull-down current and the reference voltage. The feedback control unit is used to compare the reference voltage with the voltage corresponding to the sampled current, and adjust the G pole voltage of the power tube according to the comparison result, thereby adjusting the output current of the circuit.

[0059] Combine the following Figure 8 The specific circuit diagram of the above-mentioned temperature-based current limiting protection circuit is described.

[0060] The power unit includes a power tube M0, and the sampling unit includes a sampling tube M1. The size ratio coefficient of the power tube M0 and the sampling tube M1 is K:1. Therefore, the current I sampled by the sampling tube M1 is SET =I L / K. The load unit includes a resistor R L and capacitor C L The feedback control unit includes MOS tube M2, resistor R SET , op amps csamp and main_amp, where csamp is a clamp op amp and main_amp is a current limiting regulator main op amp. In addition to the negative input of main_amp connected to the reference voltage V REF_OC In addition, the connection of power unit, sampling unit, load unit and feedback control unit can refer to the above Figure 1 The related descriptions will not be repeated here.

[0061] The reference voltage unit includes an operational amplifier buf_amp, a MOS tube M2, and resistors R1 and R2. The temperature adjustment unit includes an operational amplifier temp_amp, a transistor Q1, a current source I B , MOS tube M3.

[0062] The negative input terminal of buf_amp in the reference voltage unit is connected to the reference voltage V REF and the positive input of temp_amp, the positive input is connected to the D pole of M2 and one end of R1, the output is connected to the G pole of M2, and the positive power supply is connected to the input voltage V IN and the S pole of M2. The other end of R1 is connected to one end of R2, the D pole of M3 and the negative output terminal of main_amp, and the other end of R2 is grounded.

[0063] The current source I in the temperature control unit B The input terminal is connected to the input voltage V IN The output end is connected to the B pole, the collecting electrode (C pole) of the transistor Q1 and the negative input end of the temp_amp. The E pole of the transistor Q1 is grounded. The output end of the temp_amp is connected to the G pole of M3, and the S pole of M3 is grounded.

[0064] It should be understood that Figure 8 This is only one implementation of the temperature-based current limiting protection circuit. In other embodiments, the temperature adjustment unit may also add multiple transistors to ensure the accuracy of temperature detection. Alternatively, in other embodiments, other devices may also be used in the temperature adjustment unit, such as a device whose output signal is positively correlated with the temperature. Alternatively, in other embodiments, the voltage of the output tube may also be sampled. This application does not specifically limit the specific structure and components of the circuit.

[0065] The following is combined with the above Figures 6 to 8 The working state of the temperature-based current limiting protection circuit provided in this application is introduced in detail.

[0066] (1) Normal working mode

[0067] When the input voltage V IN and output voltage V OUT The difference is getting bigger and bigger, and the output current I L When the output current I L When the current limiting threshold is not reached, the sampling current I collected by the sampling tube M1 in the sampling unit SET Smaller, among which, I SET =I L / K. Then the sampling current I SET Flowing through resistor R SET , the voltage V generated at point A A Smaller, among which, V A =R SET *I SET. Make the reference voltage V at the negative input terminal of main_amp in the feedback control unit REF_OC Always greater than V A , where V REF_OC =V REF *R2 / (R1+R2). At this time, the main_amp in the feedback control unit will not be triggered to adjust the G pole voltage of the power tube M0.

[0068] Moreover, the junction temperature of the chip is not high at this time, so the voltage difference V BE Always greater than the reference voltage V REF Therefore, the pull-down voltage V pull It is always at a lower potential and will not activate the pull-down tube M3. Then the pull-down current I pull In this state, the reference voltage is a constant value, and the current limit threshold is also a constant value.

[0069] (2) Fixed current limiting state

[0070] When the input voltage V IN and output voltage V OUT The difference further increases, and the output current I L Reaching the current limit threshold I LIMIT4 When LIMIT4 =K*V REF_OC / R SET , the sampling current I collected by the sampling tube M1 in the sampling unit SET Reach V REF_OC / R SET . Sampling current I SET Flowing through resistor R SET , the voltage V generated at point A A The reference voltage V at the negative input of main_amp in the feedback control unit is reached REF_OC , thereby triggering the main_amp in the feedback control unit to adjust the gate voltage of the power tube M0 so that the output current I L Stable at I LIMIT4 .

[0071] With the input voltage V IN and output voltage V OUT The difference further increases, and the chip power loss P = I LIMIT4 *(V IN -V OUT ) increases accordingly, causing the chip junction temperature to rise. However, if the current limit threshold I LIMIT4 When it is low, even if V IN and V OUT The voltage difference reaches the limit (such as V OUTshort circuit to ground), chip junction temperature ψ J =ψ T +ψ JA *P will not be too high, where ψ T is the ambient temperature when the chip is working, ψ JA It is the thermal resistance from the chip die to the surrounding environment in a specific package.

[0072] At this time, the junction temperature of the chip is not high, so the voltage difference V BE Always greater than the reference voltage V REF Therefore, the pull-down voltage V pull It is always at a low potential and will not activate the pull-down tube M3. The pull-down current I in the temperature adjustment unit pull In this state, the reference voltage is constant, the current limit threshold is also constant, and the output current I L Therefore, it is also a constant value.

[0073] (3) Foldback current limiting state

[0074] When the input voltage V IN and output voltage V OUT The difference continues to increase, because the output current is always constant at I LIMIT4 , chip power loss P = I LIMIT4 *(V IN -V OUT ) increases accordingly, causing the chip junction temperature to rise. However, if the current limit threshold I LIMIT4 When the chip junction temperature is high, J =ψ T +ψ JA *P will be higher, where ψ T is the ambient temperature when the chip is working, ψ JA It is the thermal resistance from the chip die to the surrounding environment in a specific package.

[0075] If the junction temperature of the chip rises, the current I flowing through the transistor B Fixed, transistor V BE The voltage decreases as the temperature increases, making the negative input terminal V BE Reach the positive input reference voltage V REF , the reference voltage V REF Does not change with temperature, then the output voltage V pull It will rise to activate the pull-down tube M3, and the pull-down branch current I in the temperature adjustment unit pull Flows through R1 in the voltage divider resistor string in the reference voltage unit, making the reverse end reference voltage V REF_OC reduce.

[0076] At this time V REF_OC =(V REF *R2-I pull *R2) / (R1+R2), and the current limiting threshold becomes I LIMIT5 =K*V REF_OC / R SET =K*(V REF *R2-I pull *R2) / [(R1+R2)*R SET ]. Among them, I pull =G m *(V REF -V BE ), G m is the transconductance of the operational amplifier temp_amp in the temperature regulation unit.

[0077] Therefore, the input voltage V IN and output voltage V OUT The greater the difference, the higher the chip junction temperature, and the transistor V BE The lower the voltage, the lower the pull-down branch current I in the temperature control unit. pull The larger the voltage, the greater the negative terminal reference voltage V REF_OC The lower the internal current limit of the chip, LIMIT5 It will return to a lower current limit value, making the chip power loss P = I LIMIT5 *(V IN -V OUT ) is approximately constant, the chip junction temperature ψ J =ψ T +ψ JA *P is in a balanced state and is set to always be below the internal over-temperature protection threshold.

[0078] In summary, the temperature-based current limiting protection circuit provided by the present application can prevent the risk of load power failure caused by triggering over-temperature protection in the current limiting state. In addition, after the current limiting protection circuit enters the current limiting state, it will not immediately trigger the current limiting threshold foldback, and will not cause the output current capacity to decrease, greatly broadening the chip application scenarios. As the input-output voltage difference increases, the current limiting threshold will be further reduced, thereby reducing the chip junction temperature, so that the chip can work in the current limiting state for a long time without being burned by the power consumption generated by the current limiting.

[0079] On the other hand, an embodiment of the present invention further provides a chip, which is provided with a temperature-based current limiting protection circuit as described in any of the above embodiments. The chip may be an analog-to-digital conversion chip, an interface chip or a power management chip.

[0080] On the other hand, an embodiment of the present invention further provides an electronic device, which may include the above chip. The electronic device may be a mobile phone, a tablet computer, a wearable device, a vehicle-mounted device, a notebook computer, a super mobile personal computer, a netbook, or a dedicated camera (such as a SLR camera, a card camera), etc.

[0081] The various embodiments in this specification are described in a progressive, parallel, or progressive and parallel manner. Each embodiment focuses on the differences from other embodiments, and the same or similar parts between the various embodiments can be referenced to each other.

[0082] It should be noted that in the description of the present invention, it should be understood that the terms "upper", "lower", "top", "bottom", "inside", "outside" and the like indicate positions or positional relationships based on the positions or positional relationships shown in the drawings, which are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present invention. When a component is considered to be "connected" to another component, it may be directly connected to the other component or there may be a centrally arranged component at the same time.

[0083] It should also be noted that, in this article, relational terms such as first and second, etc. are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "comprises", "comprising" or any other variants thereof are intended to cover non-exclusive inclusion, so that an article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such article or device. In the absence of further restrictions, the elements defined by the sentence "comprising a ..." do not exclude the existence of other identical elements in the article or device including the above elements.

[0084] The above description of the disclosed embodiments enables those skilled in the art to implement or use the present application. Various modifications to these embodiments will be apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present application. Therefore, the present application will not be limited to the embodiments shown herein, but will conform to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A temperature-based current limiting protection circuit, characterized in that: The circuit includes a feedback control unit, a reference voltage unit, a temperature adjustment unit and a power unit, wherein: The temperature adjustment unit is used to generate a pull-down signal according to the current temperature; Wherein, the temperature adjustment unit is used to generate a pull-down signal according to the temperature, including: The temperature adjustment unit is used to generate a temperature reference signal according to the temperature; The temperature adjustment unit is further used to determine the pull-down signal according to the temperature reference signal and the reference signal, wherein the pull-down signal is used to indicate whether the temperature reference signal reaches the reference signal; 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 adjustment unit determines the pull-down signal as a second pull-down signal; wherein the reference signal determined by the reference voltage unit according to the second pull-down signal is less than the reference signal determined by the reference voltage unit according to the first pull-down signal; The reference voltage unit is used to determine a reference signal according to the pull-down signal; The feedback control unit is used to compare the reference signal with the sampling signal of the power unit, and determine the control signal for the power unit according to the comparison result; The power unit is used to determine an output signal according to the control signal.

2. The temperature-based current limiting protection circuit according to claim 1, characterized in that: The circuit further comprises a sampling unit, wherein: The sampling unit is used to collect the output signal of the power unit to obtain the sampling signal.

3. The temperature-based current limiting protection circuit according to claim 1, characterized in that: The feedback control unit is used to compare the reference signal with the sampling signal of the power unit, and determine the control signal for the power unit according to the comparison result, including: The feedback control unit is used to compare the reference signal with the sampling signal. 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; wherein the first control signal makes the output signal of the power unit less than a set threshold, and the second control signal makes the output signal of the power unit equal to the set threshold.

4. The temperature-based current limiting protection circuit according to claim 1, characterized in that: The temperature adjustment unit includes a temperature acquisition element, and the temperature acquisition element is used to generate the temperature reference signal. The temperature reference signal is positively correlated or negatively correlated with the current temperature.

5. The temperature-based current limiting protection circuit according to claim 4, characterized in that: The temperature collection element is one or more triodes.

6. The temperature-based current limiting protection circuit according to claim 5, characterized in that: The temperature adjustment unit further includes an operational amplifier, and the operational amplifier is used to determine the pull-down signal according to the temperature reference signal and the reference signal.

7. The temperature-based current limiting protection circuit according to claim 6, characterized in that: Based on the sampling signal reaching the reference signal and the temperature reference signal reaching the base signal, the temperature adjustment unit is further configured to determine that the pull-down signal is not zero.

8. A chip, characterized in that: The chip is formed with a temperature-based current limiting protection circuit as described in any one of claims 1 to 7.

9. An electronic device, characterized in that: The electronic device comprises a chip, in which the temperature-based current limiting protection circuit as claimed in any one of claims 1 to 7 is formed.

Images