CN112769093A - Current-limiting control circuit, chip and power supply - Google Patents
Current-limiting control circuit, chip and power supply Download PDFInfo
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02H—EMERGENCY PROTECTIVE CIRCUIT ARRANGEMENTS
- H02H3/00—Emergency protective circuit arrangements for automatic disconnection directly responsive to an undesired change from normal electric working condition with or without subsequent reconnection ; integrated protection
- H02H3/08—Emergency protective circuit arrangements for automatic disconnection directly responsive to an undesired change from normal electric working condition with or without subsequent reconnection ; integrated protection responsive to excess current
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02H—EMERGENCY PROTECTIVE CIRCUIT ARRANGEMENTS
- H02H9/00—Emergency protective circuit arrangements for limiting excess current or voltage without disconnection
- H02H9/02—Emergency protective circuit arrangements for limiting excess current or voltage without disconnection responsive to excess current
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02H—EMERGENCY PROTECTIVE CIRCUIT ARRANGEMENTS
- H02H9/00—Emergency protective circuit arrangements for limiting excess current or voltage without disconnection
- H02H9/02—Emergency protective circuit arrangements for limiting excess current or voltage without disconnection responsive to excess current
- H02H9/025—Current limitation using field effect transistors
Abstract
The application discloses current-limiting control circuit, chip and power relates to protection circuit design technical field. The current-limiting control circuit comprises an input interface, an output interface, a current sampling circuit, a differential amplification circuit, a current-limiting protection circuit and a power control circuit. When the current-limiting control circuit provided by the application supplies power to a load, the current sampling circuit samples the current of an electric signal input by the input interface, the sampling result is amplified by the differential amplification circuit and then input to the current-limiting protection circuit, and once the amplified signal input to the current-limiting protection circuit reaches a current-limiting point, the current-limiting protection circuit controls the power control circuit to be switched off so as to realize the current-limiting control of the current output to the output interface.
Description
Technical Field
The application relates to the technical field of protection circuit design, in particular to a current-limiting control circuit, a chip and a power supply.
Background
The overcurrent protection circuit is an indispensable component in products such as power supplies and can be generally divided into an off-type overcurrent protection circuit and a current-limiting overcurrent protection circuit. When a fault exists in the current-limiting type overcurrent protection circuit and the current-limiting point is reached, the output voltage of the circuit is reduced along with the fault so as to realize current-limiting protection. Meanwhile, the current-limiting type overcurrent protection circuit can be automatically recovered after the fault is eliminated, and the current-limiting type overcurrent protection circuit is widely applied based on the current-limiting type overcurrent protection circuit.
However, although the current-limiting overcurrent protection circuit has a better current-limiting protection performance, the voltage ranges of the input end and the output end are limited.
Disclosure of Invention
The embodiment of the application provides a current-limiting control circuit, includes:
an input interface, and an output interface;
the input end of the current sampling circuit is connected with the input interface so as to sample the current of the input electric signal;
the first input end of the differential amplifying circuit is connected with the input interface, and the second input end of the differential amplifying circuit is connected with the output end of the current sampling circuit so as to amplify a differential pressure signal existing at the two ends of the current sampling circuit;
a current-limiting protection circuit, a first input end of which is connected with the input interface, a second input end of which is connected with the output end of the differential amplification circuit, and a third input end of which acquires reference voltage;
the first input end of the power control circuit is connected with the output end of the current sampling circuit, the second input end of the power control circuit is connected with the output end of the current limiting protection circuit, and the output end of the power control circuit is connected with the output interface;
when the magnitude of the electric signal input to the current-limiting protection circuit by the differential amplification circuit reaches a current-limiting point realized in the current-limiting protection circuit based on the reference voltage, the current-limiting protection circuit controls the power control circuit to be switched off so as to realize current-limiting control on the output current of the current-limiting control circuit.
The embodiment of the application also provides a chip, and the current-limiting control circuit is integrated on the chip.
The embodiment of the application also provides a power supply, which comprises the current-limiting control circuit.
The embodiment of the application adopts at least one technical scheme which can achieve the following beneficial effects:
in the current-limiting control circuit, the chip and the power supply provided by the embodiment of the application, through the ingenious design of the current-limiting control circuit, the current-limiting control circuit can realize the current-limiting protection function of the circuit and ensure the safety of the circuit when in short circuit or overcurrent, and can also ensure a wider voltage range between an input end and an output end.
Drawings
The accompanying drawings, which are included to provide a further understanding of the application and are incorporated in and constitute a part of this application, illustrate embodiment(s) of the application and together with the description serve to explain the application and not to limit the application. In the drawings:
fig. 1 is a schematic circuit diagram of a conventional linear current-limiting protection circuit.
Fig. 2 is a block diagram of a current limit control circuit according to an embodiment of the present disclosure.
Fig. 3 is a schematic circuit structure diagram of a current sampling circuit according to an embodiment of the present disclosure.
Fig. 4 is a schematic circuit structure diagram of a differential amplifier circuit according to an embodiment of the present disclosure.
Fig. 5 is a schematic circuit structure diagram of a current limiting protection circuit according to an embodiment of the present disclosure.
Fig. 6 is a schematic circuit structure diagram of a power control circuit according to an embodiment of the present disclosure.
Fig. 7 is a schematic circuit diagram of a reference voltage generating circuit according to an embodiment of the present disclosure.
Fig. 8 is a schematic circuit structure diagram of a current limit control circuit according to an embodiment of the present disclosure.
Fig. 9 is a schematic block diagram of a current limit control circuit according to a second embodiment of the present disclosure.
Fig. 10 is a schematic circuit structure diagram of a self-latching reset circuit according to a second embodiment of the present application.
Fig. 11 is a schematic circuit structure diagram of a current limit control circuit according to a second embodiment of the present disclosure.
Fig. 12 is a schematic circuit structure diagram of a current limit control circuit according to a third embodiment of the present application.
Detailed Description
In order to make the objects, technical solutions and advantages of the present application more apparent, the technical solutions of the present application will be described in detail and completely with reference to the following specific embodiments of the present application and the accompanying drawings. It should be apparent that the described embodiments are only some of the embodiments of the present application, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present application.
Through research, the current-limiting overcurrent protection circuit is mainly adopted to realize the current-limiting protection of the circuit at present, but the practical application of the current-limiting overcurrent protection circuit has different limits. For example, referring to fig. 1, fig. 1 shows a current limiting type overcurrent protection circuit implemented based on an LDO (Low Dropout Regulator) chip, which has the advantages of simple circuit structure and Low manufacturing cost. However, in practical applications, the current-limiting overcurrent protection circuit has the following disadvantages:
(1) a large voltage difference exists between the input and the output of the circuit;
(2) when the current-limiting output voltage is reduced or short-circuited, the LDO has high power consumption;
(3) because the LDO chip has the limitation of the voltage difference of input and output, the circuit is not suitable for designing high-voltage output, and meanwhile, the voltage ranges of the input end and the output end of the circuit are limited;
(4) the current limiting precision is lower.
In view of this, the embodiments of the present application provide a current-limiting control circuit, a chip, and a power supply, where through a smart design of a circuit structure, an output current can be timely turned off or reduced under the condition of overload or short circuit of a circuit, so as to implement current-limiting protection on a load. Meanwhile, a wider voltage range can be ensured between the input end and the output end. The technical solution provided by the present application is explained in detail below with reference to the accompanying drawings, and the content is as follows.
Note that "In 1, In2, and In 3" In the following drawings denote a first input terminal, a second input terminal, and a third input terminal, respectively, "Out" denotes an output terminal, and "GND" denotes a ground, which will not be described In the following embodiments.
Example one
The current limiting control circuit 10 in the first embodiment may include, but is not limited to, the input interface Vin, the output interface Vout, the current sampling circuit 11, the differential amplifying circuit 12, the current limiting protection circuit 13, and the power control circuit 14 shown in fig. 2. The input end of the current sampling circuit 11 is connected to the input interface Vin, the output end of the current sampling circuit is connected to the second input end of the differential amplifying circuit 12 and the first input end of the power control circuit 14, the first input end of the differential amplifying circuit 12 is connected to the input interface Vin, the output end of the differential amplifying circuit 12 is connected to the second input end of the current limiting protection circuit 13, the first input end of the current limiting protection circuit 13 is connected to the input interface Vin, the third input end of the current limiting protection circuit obtains the reference voltage Vref, the output end of the current limiting protection circuit is connected to the second input end of the power control circuit 14, the output end of the power control circuit 14 is connected to the output interface Vout, the input interface Vin is used for external electrical signals, such as voltage.
While the load connected at the output interface Vout is supplied with power by the above-described current limit control circuit 10, the current sampling circuit 11 performs current sampling on the electric signal input from the input interface Vin, and inputs the sampling result into the differential amplification circuit 12 to amplify the sampling result. When the magnitude of the amplified signal input to the current limiting protection circuit 13 by the differential amplification circuit 12 reaches a current limiting point realized in the current limiting protection circuit 13 based on the reference voltage Vref, the current limiting protection circuit 13 controls the power control circuit 14 to be turned off to realize current limiting control.
As an alternative implementation, referring to fig. 3, the current sampling circuit 11 may include a first resistor R1 and a second resistor R2 that are arranged in parallel, wherein one end of the first resistor R1 and one end of the second resistor R2 are respectively connected to the input interface Vin, and the other end of the first resistor R1 and one end of the second resistor R2 are respectively connected to the first input terminal of the power control circuit 14 and the first input terminal of the differential amplifying circuit 12.
During the actual operation of the circuit, when the current limiting control circuit 10 is idle, the voltage difference between the two ends of the first resistor R1 and the second resistor R2 is zero, that is, the voltage between the two ends of the first resistor R1 (sampling resistor) is equal to the voltage between the two ends of the second resistor R2. When the current limiting control circuit 10 is not idle, a voltage difference is generated across the first resistor R1 and the second resistor R2, and the voltage difference can be amplified by the differential amplifier circuit 12. Note that, in order to make the voltage drop between the input and the output of the current limit control circuit 10 small, resistors with small resistance values may be used as the first resistor R1 and the second resistor R2.
Since the current-limiting control circuit 10 provided in the first embodiment adopts the input positive terminal current sampling, the input interface Vin and the output interface Vout can be grounded respectively to realize the common ground of the input and the output of the current-limiting control circuit 10, so that a loop is formed between the input and the output of the circuit and the ground GND, and further the electromagnetic harmonic interference generated in the working process of the circuit is transferred, and the circuit precision is improved.
In addition, because the voltage input at the input interface Vin fluctuates or when the load is connected to the output interface Vout, the current output to the load fluctuates, and thus the ripple phenomenon occurs to the circuit voltage, in order to avoid the ripple phenomenon and improve the stability of the circuit, in a possible implementation manner, a first filter capacitor for filtering the electric signal input by the input interface Vin may be connected between the input interface Vin and the ground, and a second filter capacitor for filtering the electric signal output by the output interface Vout may be connected between the output interface Vout and the ground.
Further, as an alternative implementation, as shown in fig. 4, the differential amplifying circuit 12 may include, but is not limited to, a third resistor R3, a fourth resistor R4, a fifth resistor R5, a twenty-third resistor R23, and a first operational amplifier U1. One end of the third resistor R3 is connected to the input interface Vin, the other end of the third resistor R3 is connected to the positive input terminal of the first operational amplifier U1 and one end of the twenty-third resistor R23, and the other end of the twenty-third resistor R23 is grounded; one end of the fourth resistor R4 is connected to the output end of the current sampling circuit 11, and the other end is connected to the inverting input end of the first operational amplifier U1; the two ends of the fifth resistor R5 are connected across the inverting input terminal and the output terminal of the first operational amplifier U1, and the output terminal of the first operational amplifier U1 is further connected to the second input terminal of the current limiting protection circuit 13.
In practical implementation, the implementation process of the differential amplifier circuit 12 shown in fig. 4 is as follows: when the current-limiting control circuit 10 is idle, and the ratio of the twenty-third resistor R23 to the third resistor R3 is equal to the ratio of the fifth resistor R5 to the fourth resistor R4, because zero voltage difference exists between the two ends of the first resistor R1 and the second resistor R2, the voltages at the two ends of the third resistor R3 and the fourth resistor R4 are also equal, the voltages at the two ends of the twenty-third resistor R23 and the fifth resistor R5 are also equal, and therefore the voltages at the positive input end and the negative input end of the first operational amplifier U1 are equal, that is, the output end of the first operational amplifier U1 is zero.
When the current-limiting control circuit 10 is not idle, and the ratio of the twenty-third resistor R23 to the third resistor R3 is equal to the ratio of the fifth resistor R5 to the fourth resistor R4, a voltage difference exists between two ends of the first resistor R1 and the second resistor R2, and a voltage difference also exists between the positive input end and the negative input end of the first operational amplifier U1, so that the first operational amplifier U1 may amplify the voltage difference signal according to a preset multiple (e.g., 10 times, 20 times, etc.) and then input the amplified voltage difference signal into the current-limiting protection circuit 13. It should be noted that in the present embodiment, the amplification factor of the differential amplification circuit 12 when amplifying the differential signal may be adjusted by adjusting the ratio of the twenty-third resistor R23 to the third resistor R3 (the ratio of the fifth resistor R5 to the fourth resistor R4), for example, when R23/R3 is R5/R4 is 10, then the first operational amplifier U1 may amplify the differential signal by 10 times and input the amplified differential signal into the current limiting protection circuit 13.
Optionally, as a possible implementation scheme, referring to fig. 4 again, the differential amplifying circuit 12 may further include a sixth resistor R6 and a first capacitor C1, two ends of the sixth resistor R6 are respectively connected to the first operational amplifier U1 and the input interface Vin, one end of the first capacitor C1 is grounded, and the other end is connected between the sixth resistor R6 and the first operational amplifier U1. In this implementation scheme, the sixth resistor R6 and the first capacitor C1 are provided, so that the isolation and filtering effects on the differential amplifier circuit 12 can be achieved, and the circuit performance can be improved.
Further, as an optional implementation scheme, the current-limiting protection circuit 13 may include a seventh resistor R7, an eighth resistor R8, a ninth resistor R9, a tenth resistor R10, a second operational amplifier U2, a first transistor Q1, a second transistor Q2, and a third transistor Q3 as shown in fig. 5.
One end of the seventh resistor R7 is externally connected with a reference voltage Vref, and the other end is respectively connected with the reverse input end of the second operational amplifier U2, the base b of the first triode Q1 and the base b of the third triode Q3; the positive input end of the second operational amplifier U2 is connected with the output end of the differential amplification circuit 12, and the output end is connected with the base b of the first triode Q1 and the base b of the third triode Q1 respectively; one end of the eighth resistor R8 is connected with the input interface Vin, the other end is respectively connected with the collector c of the first triode Q1 and the base b of the second triode Q2, and the emitter e of the first triode Q1 is grounded; one end of the ninth resistor R9 is connected to the second input end of the power control circuit 14, the other end is connected to the collector c of the second triode Q2, and the emitter e of the second triode Q2 is grounded; one end of the tenth resistor R10 is used for obtaining the reference voltage Vref, and the other end is connected to the collector c of the third transistor Q3, the collector c of the third transistor Q3 is also used for externally connecting the reference voltage Vs, and the emitter e is grounded, where 0< Vs < Vref.
When the current limiting control circuit 10 is not idle, the amplified signal output by the differential amplifying circuit 12 is input to the positive input terminal of the second operational amplifier U2, at this time, the third transistor Q3 is turned off, and the reference voltage Vs is equal to the reference voltage Vref, so that when the reference signal Vref input to the inverting input terminal of the second operational amplifier U2 reaches the reference voltage Vs, it outputs a high level to the base of the first transistor Q1 to drive the first transistor Q1 to be turned on, and further pulls down the base current of the second transistor Q2 to turn off the second transistor Q2, thereby controlling the power control circuit 14 to be turned off to limit the output current of the current limiting control circuit 10.
In addition, when the current limit control circuit 10 reaches the current limit state, the high level output by the second operational amplifier U2 drives the third transistor Q3 to turn on, so that when the reference voltage Vs drops, the reference voltage Vref input to the second operational amplifier U2 changes, and the output current drops to zero.
In a possible implementation manner, the current-limiting protection circuit 13 may further include a fourth capacitor C4 and a diode D as shown in fig. 5, an anode of the diode D is connected to the output terminal of the differential amplification circuit 12, a cathode of the diode D is connected to the base b of the third transistor Q3 and one end of the fourth capacitor C4, respectively, and the other end of the fourth capacitor C4 is grounded. The fourth capacitor C4 is used to ensure that the action of the third transistor Q3 lags behind the action of the first transistor Q1, and the diode D is used to realize circuit isolation.
In yet another possible implementation manner, the current-limiting protection circuit 13 may further include an eleventh resistor R11, a twelfth resistor R12, a thirteenth resistor R13, a fourteenth resistor R14, a second capacitor C2, and a third capacitor C3 as shown in fig. 5, where the second capacitor C2 and the third capacitor C3 are used as filter capacitors, and the eleventh resistor R11, the twelfth resistor R12, the thirteenth resistor R13, and the fourteenth resistor R14 are used as voltage-dropping resistors, so as to implement protection of the lower-stage input circuit. It should be noted that the connection relationship between the devices may be, but is not limited to, as shown in fig. 5.
Further, as shown in fig. 6, the power control circuit 14 may include a power switch device M, a source s of the power switch device M is connected as a first input end to the output end of the current sampling circuit 11, a gate g is connected as a second input end to the output end of the current limiting protection circuit 13, and a drain d is connected as an output end to the output interface Vout. The power switch device M may be, but is not limited to, a P-type MOS transistor.
As a possible implementation, the power control circuit 14 may further include a soft-start control branch, which includes the zener diode ZD shown in fig. 6, a fifth capacitor C5 and a fifteenth resistor R15. Two ends of the zener diode ZD, two ends of the fifth capacitor C5, and two ends of the fifteenth resistor R15 are all connected across the source s and the gate g of the power switch device M.
As for the reference voltage Vref referred to in the above current limiting protection circuit 13, in order to realize a high-precision reference, as an alternative implementation, as shown in fig. 7, the reference voltage Vref may be generated by a reference voltage generation circuit 16. The reference voltage generating circuit 16 may include a twenty-second resistor R22, an eighth capacitor C8, and a low dropout regulator LDO. One end of the twenty-second resistor R22 is connected to the input interface Vin, and the other end is connected to the input end of the low dropout regulator LDO and the third input end of the current limiting protection circuit 13; the output end of the low dropout regulator LDO is connected to one end of an eighth capacitor C8 and the third input end of the current limiting protection circuit 13, respectively, and the other end of the eighth capacitor C8 is grounded.
Based on the above description of the current limit control circuit 10, the current limit control circuit 10 shown in fig. 8 is taken as an example, and the operation principle of the current limit control circuit 10 in the first embodiment is described below by taking an example of an input voltage at the input interface Vin being 27.5V, a current limit point being 0.5A, a reference voltage Vref being 2.5V, and an amplification factor of the differential amplification circuit 12 being 10 times. In fig. 10, E1 is a first filter capacitor, and E2 is a second filter capacitor.
(1) When the current-limiting control circuit 10 is idle, and the ratio of the twenty-third resistor R23 to the third resistor R3 is equal to the ratio of the fifth resistor R5 to the fourth resistor R4, the voltage at the two ends of the sampling resistor is equal because the voltage at the two ends of the first resistor R1 and the second resistor R2 in the current sampling circuit 11 is zero-voltage difference, the voltage at the two ends of the sampling resistor is equal, the voltage at R3 is equal to R4 and R23 is equal to R5, the divided voltages are also equal, the input voltage of the first operational amplifier U1 is equal, and the output voltage is 0V.
(2) When the current-limiting control circuit 10 is not idle, and the ratio of the twenty-third resistor R23 to the third resistor R3 is equal to the ratio of the fifth resistor R5 to the fourth resistor, a voltage difference is generated between two ends of the first resistor R1 and the second resistor R2, and when the load current is equal to 0.5A, the voltage difference between two ends of the sampling resistor (the first resistor R1 and the second resistor R2) in the current sampling circuit 11 is equal to 0.25V, and a voltage difference of 0.25V is simultaneously generated between two input ends of the first operational amplifier U1, then, after the voltage amplification is performed by the differential amplification circuit 12, one path of the output voltage passes through the eleventh resistor R11 and is input to the positive input end of the second operational amplifier U2, at this time, since the third triode Q3 is cut off, the reference voltage Vs is equal to 2.5V, and the inverting input of the second operational amplifier U2 is 2.5V. When the input signal of the second operational amplifier U2 reaches the reference voltage Vref (2.5V), the second operational amplifier U2 outputs a high level to drive the first transistor Q1 to be turned on through the thirteenth resistor R13, and further pull down the base current of the second transistor Q2, so that the second transistor Q2 is turned off, and the power switch device M is turned off, thereby realizing the current-limiting control of the output current of the current-limiting control circuit 10.
(3) If the circuit state needs to be maintained, the circuit is continuously repeated, the current of 500MA is continuously flowed through the power switch device M, a large voltage difference occurs between the input and the output of the power switch device M (when the output is short-circuited, the voltage difference is equal to the input voltage), and the loss of the power switch device M is 27.5 × 0.5 — 13W, so that the application of the circuit is limited. In contrast, when the output current reaches the current limit of 0.5A, the other path of the high level output by the second operational amplifier U2 drives the third transistor Q3 to turn on through the diode D and the fourteenth resistor R14, the voltage of the reference voltage Vs drops, the comparison current (the reference voltage Vref) input by the second operational amplifier U2 is changed, and the output current drops to 0.
As can be seen from the above, the current limiting control circuit 10 in the first embodiment has at least the following advantages:
(1) by adopting forward current sampling, input and output common ground and harmonic interference transfer can be realized.
(2) Since the current limiting control circuit 10 provided by the present application is controlled to ground (the first transistor Q1, the second transistor Q2, etc.), as long as the withstand Voltage (VDs) of the power switch M in the power control circuit 14 can be satisfied, the current limiting control circuit 10 is not limited by the magnitude of the input voltage, and the current limiting control circuit 10 is ensured to have a large input voltage range and high current limiting precision.
(3) The circuit is simple, and the differential amplifier circuit 12 can make the input and the output have lower voltage difference. At the same time, when the current limiting is performed, there is no need to limit the magnitude of the differential pressure between the input and the output.
(4) The circuit design realizes the output short circuit or the closing under the overcurrent or the reduction of the output current, reduces the loss of the power tube, avoids the failure of the power tube caused by the power consumption problem, and effectively protects the safety of load equipment.
(5) Due to the low voltage difference between the input and output, the RDS efficiency reaches 100% ignoring MOS.
(6) For the situation that a high-power load needs to be driven, the high-power expansion can be realized by adjusting the model of the power switch tube M in the power control circuit 14, in other words, the current-limiting control circuit 10 provided by the present application is suitable for the high-power expansion.
Example two
Since the current limit of the current limit control circuit 10 and the change of the reference voltage Vs have continuous sustainability, when the current limit control provided in the first embodiment enters the current limit point, that is, the circuit enters the self-locking state, even if the load returns to normal, the circuit needs to be powered off and restarted to recover the circuit, which brings inconvenience to practical application. In contrast, as shown in fig. 9, in the second embodiment, a current limiting control circuit 10 is provided, in which a self-locking reset circuit 17 is added to the current limiting control circuit 10 in the first embodiment, so as to implement self-locking reset of the current limiting control circuit 10 when the load returns to normal.
Referring to fig. 10, the self-latch reset circuit 17 includes a seventeenth resistor R17, an eighteenth resistor R18, a nineteenth resistor R19, a twentieth resistor R20, a third operational amplifier U3, a fourth operational amplifier U4, and a fourth transistor Q4. The positive input end of the third operational amplifier U3 is connected to the output end of the differential amplifier circuit 12, the output end is connected to the inverting input end, and one end of the twentieth resistor R20 is connected to the inverting input end; one end of the eighteenth resistor R18 is used for acquiring the reference voltage Vref, and the other end is connected to one end of the seventeenth resistor R17 and the positive input end of the fourth operational amplifier U4, respectively, and the other end of the seventeenth resistor R17 is grounded; the other end of the twentieth resistor R20 is connected to one end of the nineteenth resistor R19 and the inverting input terminal of the fourth operational amplifier U4, respectively; the base b of the fourth triode Q4 is connected to the output terminal of the fourth operational amplifier U4, the collector c is connected to the fourth input terminal of the current limiting protection circuit 13, and the emitter e is grounded. The third operational amplifier U3 and the sixteenth resistor R16 can form a follower circuit to realize the isolation of the input and output signals.
Optionally, in an implementation scheme, the self-locking reset circuit 17 may further include a sixth capacitor C6, a seventh capacitor C7, and a twenty-first resistor R21 as shown in fig. 10. The sixth capacitor C6 and the seventh capacitor C7 are used for realizing circuit filtering, and the twenty-first resistor R21 is used as a voltage drop resistor.
Further, referring to fig. 11, the operation principle of the current limiting control circuit 10 in the second embodiment is described by taking the input voltage at the input interface Vin as 27.5V, the current limiting point as 0.5A, the reference voltage Vref as 2.5V, and the amplification factor of the differential amplification circuit 12 as 10 times as an example.
Assuming that the current limiting control circuit 10 is already in the current limiting state, the amplified signal outputted from the differential amplifier circuit 12 enters the self-locking reset circuit 17 through the sixteenth resistor R16 and the positive input terminal of the third operational amplifier U3, and the reference voltage Vref is divided by the seventeenth resistor R17 and the eighteenth resistor R18 to provide a fixed current recovery signal to the fourth operational amplifier U4.
Meanwhile, after a current detection signal output by the third operational amplifier U3 is divided by the nineteenth resistor R19 and the twentieth resistor R20, the current detection signal flows into the fourth operational amplifier U4 from the inverting input terminal, and if the current detection signal input by the inverting input terminal of the fourth operational amplifier U4 is smaller than the reference voltage Vref input by the forward input terminal, the fourth operational amplifier U4 outputs a high level to drive the fourth triode Q4 to be turned on, so as to pull down the base current of the third triode Q3, so that the third triode Q3 is turned off to recover the reference voltage Vref of 2.5V, that is, the self-locking reset of the current limiting control circuit 10 is realized. It should be noted that, in the present embodiment, the level of the output terminal of the third operational amplifier U3 and the level of the output terminal of the fourth operational amplifier U4 can be determined according to the turn-on voltage of the corresponding transistor, which is not limited herein.
EXAMPLE III
In order to avoid the problem of burning out or shortening the life of the current limiting control circuit 10 due to instant power-up, compared to the current limiting control circuit 10 in the first or second embodiment, the current limiting control circuit 10 in the third embodiment further includes a full-load start branch 15 as shown in fig. 12, where the full-load start branch 15 may include a ninth capacitor C9; the ninth capacitor C9 is connected across the twenty-third resistor R23.
In actual operation, because the twenty-third resistor R23 and the ninth capacitor C9 are connected in parallel, the ninth capacitor C9 needs to be charged, so that the current control loop of the current-limiting control circuit 10 is opened at the time of power-on, and full-load starting of a load is realized. The size of the ninth capacitor C9 determines the time for the current control circuit to output the full-load starting voltage.
In the current-limiting control circuit 10 according to the third embodiment, the full-load starting at the power-on time can be realized by setting the full-load starting branch 15, and the problems of circuit burnout and the like caused by instantaneous power-on are effectively avoided.
Example four
The fourth embodiment provides a chip, on which the current limiting control circuit 10 as given in the first embodiment, the second embodiment or the third embodiment is integrated, and since the chip has the same or corresponding technical features as the current limiting control circuit 10 as given in the first embodiment, the second embodiment or the third embodiment, the detailed description of the chip in the fourth embodiment can refer to the detailed description of the current limiting control circuit 10 in the first embodiment, the second embodiment or the third embodiment, and the detailed description of the chip in the fourth embodiment is omitted here.
EXAMPLE five
A fifth embodiment provides a power supply, where the power supply includes the current-limiting control circuit 10 as shown in the first embodiment, the second embodiment, or the third embodiment, and since the current-limiting control circuit 10 in the power supply has the same or corresponding technical features as the current-limiting control circuit 10 shown in the first embodiment, the second embodiment, or the third embodiment, the detailed description of the current-limiting control circuit 10 in the fifth embodiment can refer to the detailed description of the current-limiting control circuit 10 in the first embodiment, the second embodiment, or the third embodiment, and the detailed description of the current-limiting control circuit 10 in the fifth embodiment is omitted here.
The above description is only an example of the present application and is not intended to limit the present application. Various modifications and changes may occur to those skilled in the art. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application should be included in the scope of the claims of the present application.
Claims (12)
1. A current limit control circuit, comprising:
the input interface and the output interface are respectively grounded;
the input end of the current sampling circuit is connected with the input interface so as to sample the current of the input electric signal;
the first input end of the differential amplifying circuit is connected with the input interface, and the second input end of the differential amplifying circuit is connected with the output end of the current sampling circuit so as to amplify a differential pressure signal existing at the two ends of the current sampling circuit;
a current-limiting protection circuit, a first input end of which is connected with the input interface, a second input end of which is connected with the output end of the differential amplification circuit, and a third input end of which acquires reference voltage;
the first input end of the power control circuit is connected with the output end of the current sampling circuit, the second input end of the power control circuit is connected with the output end of the current limiting protection circuit, and the output end of the power control circuit is connected with the output interface;
when the magnitude of the electric signal input to the current-limiting protection circuit by the differential amplification circuit reaches a current-limiting point realized in the current-limiting protection circuit based on the reference voltage, the current-limiting protection circuit controls the power control circuit to be switched off so as to realize current-limiting control on the output current of the current-limiting control circuit.
2. The current-limiting control circuit of claim 1, wherein the current sampling circuit comprises a first resistor and a second resistor connected in parallel, one end of the first resistor and one end of the second resistor are respectively connected to the input interface, and the other end of the first resistor and the other end of the second resistor are respectively connected to the first input terminal of the power control circuit and the first input terminal of the differential amplification circuit.
3. The current-limiting control circuit of claim 1, wherein the differential amplification circuit comprises a third resistor, a fourth resistor, a fifth resistor, a twenty-third resistor, and a first operational amplifier;
one end of the third resistor is connected with the input interface, the other end of the third resistor is respectively connected with the positive input end of the first operational amplifier and one end of the twenty-third resistor, and the other end of the twenty-third resistor is grounded;
one end of the fourth resistor is connected with the output end of the current sampling circuit, and the other end of the fourth resistor is connected with the reverse input end of the first operational amplifier;
two ends of the fifth resistor are bridged between the reverse input end and the output end of the first operational amplifier, and the output end of the first operational amplifier is also connected with the second input end of the current-limiting protection circuit.
4. The current-limiting control circuit of claim 3 wherein the differential amplification circuit further comprises a full-load start branch comprising a ninth capacitor; the ninth capacitor is connected across two ends of the twenty-third resistor in a bridge connection mode.
5. The current-limiting control circuit of claim 1, wherein the current-limiting protection circuit comprises a seventh resistor, an eighth resistor, a ninth resistor, a tenth resistor, a second operational amplifier, a first transistor, a second transistor, and a third transistor;
one end of the seventh resistor is externally connected with the reference voltage, and the other end of the seventh resistor is respectively connected with the reverse input end of the second operational amplifier, the base electrode of the first triode and the base electrode of the third triode;
the positive input end of the second operational amplifier is connected with the output end of the differential amplification circuit, and the output end of the second operational amplifier is respectively connected with the base electrode of the first triode and the base electrode of the third triode;
one end of the eighth resistor is connected with the input interface, the other end of the eighth resistor is respectively connected with the collector of the first triode and the base of the second triode, and the emitter of the first triode is grounded;
one end of the ninth resistor is connected with the second input end of the power control circuit, the other end of the ninth resistor is connected with the collector of the second triode, and the emitter of the second triode is grounded;
one end of the tenth resistor is used for acquiring reference voltage, the other end of the tenth resistor is connected with a collector electrode of the third triode, the collector electrode of the third triode is also used for being externally connected with reference voltage, and an emitting electrode of the third triode is grounded, wherein 0< Vs < Vref.
6. The current-limiting control circuit of claim 5, wherein the current-limiting protection circuit further comprises a fourth capacitor and a diode, an anode of the diode is connected to the output terminal of the differential amplifier circuit, and a cathode of the diode is connected to the base of the third transistor and one end of the fourth capacitor, respectively.
7. The current-limiting control circuit of claim 1, wherein the power control circuit comprises a power switch device having a source connected as a first input to the output of the current sampling circuit, a gate connected as a second input to the output of the current-limiting protection circuit, and a drain connected as an output to the output interface.
8. The current-limiting control circuit of claim 7 wherein the power control circuit further comprises a soft-start control branch comprising a zener diode, a fifth capacitor, and a fifteenth resistor;
and two ends of the voltage stabilizing diode, two ends of the fifth capacitor and two ends of the fifteenth resistor are bridged between the source electrode and the grid electrode of the power switch device.
9. The current-limiting control circuit of claim 1, further comprising a self-latching reset circuit comprising a seventeenth resistor, an eighteenth resistor, a nineteenth resistor, a twentieth resistor, a third operational amplifier, a fourth operational amplifier, and a fourth transistor;
the positive input end of the third operational amplifier is connected with the output end of the differential amplification circuit, the output end of the third operational amplifier is connected with the reverse input end, and one end of the twentieth resistor is respectively connected;
one end of the eighteenth resistor is used for acquiring a reference voltage, the other end of the eighteenth resistor is connected with one end of the seventeenth resistor and the positive input end of the fourth operational amplifier respectively, and the other end of the seventeenth resistor is grounded;
the other end of the twentieth resistor is connected with one end of the nineteenth resistor and the inverting input end of the fourth operational amplifier respectively;
and the base electrode of the fourth triode is connected with the output end of the fourth operational amplifier, the collector electrode of the fourth triode is connected with the fourth input end of the current-limiting protection circuit, and the emitter electrode of the fourth triode is grounded.
10. The current-limiting control circuit of claim 1, further comprising a reference voltage generation circuit for generating the reference voltage, the reference voltage generation circuit comprising a twenty-second resistor, an eighth capacitor, and a low dropout regulator;
one end of the twenty-second resistor is connected with the input interface, and the other end of the twenty-second resistor is connected with the input end of the low dropout linear regulator and the third input end of the current-limiting protection circuit respectively;
the output end of the low dropout regulator is connected with one end of the eighth capacitor and the third input end of the current-limiting protection circuit respectively, and the other end of the eighth capacitor is grounded.
11. A chip having integrated thereon a current limiting control circuit according to any of claims 1 to 10.
12. A power supply comprising a current limiting control circuit as claimed in any one of claims 1 to 10.
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| CN201911072917.1A CN112769093B (en) | 2019-11-05 | 2019-11-05 | Current-limiting control circuit, chip and power supply |
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| CN201911072917.1A CN112769093B (en) | 2019-11-05 | 2019-11-05 | Current-limiting control circuit, chip and power supply |
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| CN113872157A (en) * | 2021-10-09 | 2021-12-31 | 广州金升阳科技有限公司 | Hysteresis comparison control circuit |
| CN115377955A (en) * | 2022-08-29 | 2022-11-22 | 苏州浪潮智能科技有限公司 | Power supply hot plug device with current-limiting function |
| CN117410928A (en) * | 2023-10-17 | 2024-01-16 | 悦芯科技股份有限公司 | Bidirectional controllable chip current-limiting detection circuit |
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|---|---|
| CN112769093B (en) | 2023-12-29 |
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