CN109861511B - Overcurrent protection circuit and overcurrent protection system - Google Patents
Overcurrent protection circuit and overcurrent protection system Download PDFInfo
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- CN109861511B CN109861511B CN201811646441.3A CN201811646441A CN109861511B CN 109861511 B CN109861511 B CN 109861511B CN 201811646441 A CN201811646441 A CN 201811646441A CN 109861511 B CN109861511 B CN 109861511B
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- 238000005070 sampling Methods 0.000 claims abstract description 100
- 230000003321 amplification Effects 0.000 claims abstract description 31
- 238000003199 nucleic acid amplification method Methods 0.000 claims abstract description 31
- 239000003990 capacitor Substances 0.000 claims description 29
- 230000000087 stabilizing effect Effects 0.000 claims description 14
- 238000000034 method Methods 0.000 abstract description 6
- 238000001514 detection method Methods 0.000 description 8
- 238000007599 discharging Methods 0.000 description 7
- 238000010586 diagram Methods 0.000 description 6
- 238000001914 filtration Methods 0.000 description 5
- 230000001960 triggered effect Effects 0.000 description 4
- 230000005611 electricity Effects 0.000 description 3
- 230000007547 defect Effects 0.000 description 2
- 230000000694 effects Effects 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
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Classifications
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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
- H02H3/087—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 for dc applications
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
- H02M1/00—Details of apparatus for conversion
- H02M1/32—Means for protecting converters other than automatic disconnection
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- Emergency Protection Circuit Devices (AREA)
- Measurement Of Current Or Voltage (AREA)
Abstract
The invention discloses an overcurrent protection circuit and an overcurrent protection system, comprising a voltage sampling module, a differential amplification module, a voltage comparison module and a control module, wherein two input ends of the differential amplification module are respectively and electrically connected with the voltage sampling module, the output end of the differential amplification module is electrically connected with one input end of the voltage comparison module, the output end of the voltage sampling module is also electrically connected with the other input end of the voltage comparison module, and the output end of the voltage comparison module is electrically connected with the control module. The invention relates to an overcurrent protection circuit and an overcurrent protection system, wherein a voltage sampling module is arranged in the output end of a power supply, so that the sampled voltage cannot be interfered by the load of the output end in the overcurrent protection process, the occurrence of false triggering of the overcurrent protection circuit is avoided, the control circuit of the power supply starts the overcurrent protection work, and the printer can work normally.
Description
Technical Field
The invention relates to the field of printer power supply, in particular to an overcurrent protection circuit and an overcurrent protection system.
Background
Many electronic devices have a rated current that is not allowed to exceed or otherwise burn out the device. Some devices have current protection modules. When the current exceeds the set current, the equipment is automatically powered off to protect the equipment. For example, the usb interface of the motherboard cpu generally has usb over-current protection to protect the motherboard from being burned out.
In the conventional printer power supply, there are often two or more paths of output, one path is a voltage output of 40V, and the other path is a voltage output of 22V, and for the over-current detection of the two or more paths of output, the over-current detection resistor is often required to be placed at a high end, i.e. placed at the output end of the positive electrode, so as to perform high-end detection. The reason that the ground detection cannot be performed is that the multiplexing output is grounded together, if the overcurrent detection resistor of each path is placed at the ground, the ground of each path participates in the shunt, and accurate overcurrent detection cannot be realized. When the loads carried by the two outputs are different, if the load adjustment rate of the power supply is not good enough, the output voltages of the two paths are often influenced, and the triggered overcurrent protection of the traditional overcurrent protection circuit is likely to be started, so that the false triggering of the overcurrent protection occurs, the chip in the power supply is triggered and protected, the power supply cannot work continuously, and the use of the printer is influenced. In addition, if the load carried by the output end of the 40V voltage is different from the load carried by the output end of the 20V voltage, the sampling precision of the overcurrent protection circuit is also affected, and thus, the condition that the overcurrent protection is triggered by mistake may also occur.
Disclosure of Invention
The invention aims to overcome the defects in the prior art and provide an overcurrent protection circuit and an overcurrent protection system which are used for more accurately sampling and avoiding false triggering.
The aim of the invention is realized by the following technical scheme:
An overcurrent protection circuit comprising: the device comprises a voltage sampling module, a differential amplification module, a voltage comparison module and a control module, wherein two input ends of the differential amplification module are respectively and electrically connected with the voltage sampling module, an output end of the differential amplification module is electrically connected with one input end of the voltage comparison module, an output end of the voltage sampling module is also electrically connected with the other input end of the voltage comparison module, and an output end of the voltage comparison module is electrically connected with the control module.
In one embodiment, the voltage sampling module includes a sampling resistor R202, a first end of the sampling resistor R202 is electrically connected to the first input terminal of the differential amplifying module, and a second end of the sampling resistor R202 is electrically connected to the second input terminal of the differential amplifying module.
In one embodiment, the differential amplifying module includes a differential amplifying unit, a first sampling unit and a second sampling unit, wherein an input end of the first sampling unit is connected with a first end of the voltage sampling module, an output end of the first sampling unit is electrically connected with an inverting input end of the differential amplifying unit, an input end of the second sampling unit is connected with a second end of the voltage sampling module, an output end of the second sampling unit is electrically connected with an in-phase input end of the differential amplifying unit, and an output end of the differential amplifying unit is electrically connected with the voltage comparing module.
In one embodiment, the differential amplifying unit includes an amplifier U602B, a non-inverting input terminal of the amplifier U602B is electrically connected to the output terminal of the second sampling unit, an inverting input terminal of the amplifier U602B is electrically connected to the output terminal of the first sampling unit, and an output terminal of the amplifier U602B is electrically connected to the input terminal of the voltage comparing module.
In one embodiment, the voltage comparison module includes a voltage comparison unit, a voltage stabilizing unit and a voltage dividing unit, the input end of the voltage dividing unit is electrically connected with the output end of the voltage sampling module, the output end of the voltage dividing unit is electrically connected with the inverting input end of the voltage comparison unit, two ends of the voltage stabilizing unit are connected with two ends of the voltage dividing unit in parallel, the non-inverting input end of the voltage comparison unit is electrically connected with the output end of the differential amplification module, and the output end of the voltage comparison unit is output to the control module.
In one embodiment, the voltage comparing unit includes a comparator U602A and a diode D606, where a non-inverting input terminal of the comparator U602A is electrically connected to an output terminal of the differential amplifying module, an inverting input terminal of the comparator U602A is electrically connected to an output terminal of the voltage dividing unit, an output terminal of the comparator U602A is electrically connected to an anode of the diode D606, and a cathode of the diode D606 is electrically connected to an input terminal of the control module.
In one embodiment, the voltage comparison module further includes a current limiting filter unit, an input end of the current limiting filter unit is electrically connected with an output end of the voltage sampling module, and an output end of the current limiting filter unit is electrically connected with an input end of the voltage dividing unit.
In one embodiment, the current-limiting filtering unit includes a current-limiting resistor R637 and a filter capacitor C613, where a first end of the current-limiting resistor R637 is electrically connected to the output end of the voltage sampling module, a second end of the current-limiting resistor R637 is electrically connected to the input end of the voltage dividing unit, a first end of the filter capacitor C613 is electrically connected to the first end of the current-limiting resistor R637, and a second end of the filter capacitor C613 is electrically connected to the negative end of the voltage comparing unit.
In one embodiment, the control module includes a control circuit and an optocoupler unit, wherein an input end of the optocoupler unit is electrically connected with an input end of the voltage comparison module, and an output end of the optocoupler unit is electrically connected with a control end of the control circuit.
The invention also provides an overcurrent protection system which comprises the overcurrent protection circuit.
Compared with the prior art, the invention has the following advantages:
The invention relates to an overcurrent protection circuit and an overcurrent protection system, which can prevent the sampled voltage from being influenced by two or multiple output adjustment rates and the load size of each output in the overcurrent protection process by arranging a voltage sampling module in the output end of a power supply. The occurrence of false triggering of the overcurrent protection circuit is avoided, so that the control circuit of the power supply starts the overcurrent protection work, and the printer can work normally.
Drawings
In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings that are needed in the embodiments will be briefly described below, it being understood that the following drawings only illustrate some embodiments of the present invention and therefore should not be considered as limiting the scope, and other related drawings may be obtained according to these drawings without inventive effort for a person skilled in the art.
FIG. 1 is a functional block diagram of an over-current protection circuit according to an embodiment of the present invention;
FIG. 2 is a circuit diagram of a voltage sampling module at the output of the overcurrent protection system shown in FIG. 1;
FIG. 3 is a circuit diagram of a control module of the over-current protection circuit shown in FIG. 1;
FIG. 4 is a circuit diagram of the over-current protection circuit shown in FIG. 1;
FIG. 5 is a functional block diagram of a delay protection circuit of an over-current protection system according to an embodiment of the present invention;
fig. 6 is a circuit diagram of a delay protection circuit of the overcurrent protection system shown in fig. 4.
Detailed Description
In order that the invention may be readily understood, a more complete description of the invention will be rendered by reference to the appended drawings. The drawings illustrate preferred embodiments of the invention. This invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete.
It will be understood that when an element is referred to as being "fixed to" another element, it can be directly on the other element or intervening elements may also be present. When an element is referred to as being "connected" to another element, it can be directly connected to the other element or intervening elements may also be present. The terms "vertical," "horizontal," "left," "right," and the like are used herein for illustrative purposes only and are not meant to be the only embodiment.
Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. The terminology used herein in the description of the invention is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. The term "and/or" as used herein includes any and all combinations of one or more of the associated listed items.
Referring to fig. 1, an overcurrent protection circuit includes: the voltage sampling module 100, the differential amplification module 200, the voltage comparison module 300 and the control module 400, wherein two input ends of the differential amplification module 200 are respectively and electrically connected with the voltage sampling module 100, an output end of the differential amplification module 200 is electrically connected with one input end of the voltage comparison module 300, an output end of the voltage sampling module 100 is also electrically connected with the other input end of the voltage comparison module 300, and an output end of the voltage comparison module 300 is electrically connected with the control module 400. It should be noted that, the voltage sampling module 100 is configured to obtain a voltage at an output end of a power supply; the differential amplification module 200 is configured to obtain voltages at two ends of the voltage sampling module, output the voltages to an input end of the voltage comparison module 300 after passing through a circuit of the differential amplification module, and output the voltages to the control module by the voltage comparison module 300 after comparing the voltages with the voltages output by the voltage sampling module; the control module 400 is configured to implement over-current protection of the power supply.
Therefore, by arranging the voltage sampling module in the output end of the power supply, the sampled voltage can not be interfered by the load of the output end in the overcurrent protection process, false triggering of the overcurrent protection circuit is avoided, the control circuit of the power supply starts the overcurrent protection work, and the printer can work normally.
It should be noted that, referring to fig. 2, the voltage sampling module includes a sampling resistor R202, a first end of the sampling resistor R202 is electrically connected to the first input end of the differential amplifying module, and a second end of the sampling resistor R202 is electrically connected to the second input end of the differential amplifying module. By setting the sampling resistor, the voltage of the power output end can be obtained, so that the current of the power output end can be detected.
It should be noted that, the differential amplification module includes differential amplification unit, first sampling unit and second sampling unit, the input of first sampling unit with the first end of voltage sampling module is connected, the output of first sampling unit with the reverse phase input of differential amplification unit is electric, the input of second sampling unit with the second end of voltage sampling module is connected, the output of second sampling unit with the homophase input of differential amplification unit is electric, the output of differential amplification unit with the voltage comparison module is electric to be connected. The first sampling unit is configured to obtain a first voltage 40V-2 at one side of the sampling resistor R202, the second sampling unit is configured to obtain a second voltage 40V at the other side of the sampling resistor R202, and then transmit the two sampled voltages to the differential amplifying unit, if the differential pressure of the two voltages increases linearly, the voltage at the output end of the differential amplifying unit also increases linearly, and then the increased voltage is transmitted to the voltage comparing module.
Specifically, referring to fig. 3, the differential amplifying unit includes an amplifier U602B, a non-inverting input terminal of the amplifier U602B is electrically connected to an output terminal of the second sampling unit, an inverting input terminal of the amplifier U602B is electrically connected to an output terminal of the first sampling unit, and an output terminal of the amplifier U602B is electrically connected to an input terminal of the voltage comparing module. The amplifier U602B is configured to amplify the voltages at two input terminals.
Specifically, the first sampling unit includes a resistor R629 and a resistor R630, a first end of the resistor R629 is electrically connected to a first end of the sampling resistor R202, a second end of the resistor R629 is electrically connected to a non-inverting input end of the amplifier U602B, and two ends of the resistor R630 are connected in parallel to two ends of the resistor R629.
Specifically, the second sampling unit includes a capacitor C616 and a resistor R623, a first end of the resistor R623 is electrically connected to a second end of the sampling resistor R202, second ends of the resistor R623 are respectively connected to one end of the capacitor C616, and a second end of the resistor R623 is directly electrically connected to an inverting input end of the amplifier U602B. In general, to achieve higher detection accuracy, the parallel resistance value of the resistor R629 and the resistor R630 should be equal to the resistance value of the resistor R623, the resistor R622 should be equal to the resistance value of the resistor R633, and the resistor R634 should be equal to the resistance value of the resistor R635. So that the sampled voltage is not affected by other factors.
It should be noted that, the voltage comparison module includes voltage comparison unit, steady voltage unit and bleeder unit, bleeder unit's input with voltage sampling module's output electricity is connected, bleeder unit's output with voltage comparison unit's inverting input end electricity is connected, steady voltage unit's both ends with bleeder unit's both ends parallel connection, voltage comparison unit's homophase input with differential amplification module's output electricity is connected, voltage comparison unit's output is exported in the control module.
Specifically, the voltage comparison unit includes a comparator U602A and a diode D606, where a non-inverting input end of the comparator U602A is electrically connected to an output end of the differential amplification module, an inverting input end of the comparator U602A is electrically connected to an output end of the voltage division unit, an output end of the comparator U602A is electrically connected to an anode of the diode D606, and a cathode of the diode D606 is electrically connected to an input end of the control module.
In operation, in the voltage comparison module, the voltage stabilizing unit and the voltage dividing unit are arranged, and the voltage input end of the voltage dividing unit is also from the voltage sampling module, namely the output voltage of 40V-2 in the figure, so that the voltage input to the inverting input end of the comparator U602A is basically kept unchanged from beginning to end. Since the voltage at the output terminal of the amplifier U602B increases with the increase of the differential voltage between the first voltage 40V-2 of the first sampling unit and the second voltage 40V of the second sampling unit, the voltage at the non-inverting input terminal of the comparator U602A also increases, and when the voltage at the non-inverting input terminal of the comparator U602A is greater than the voltage at the inverting input terminal, i.e. the output voltage difference between 40V-2 and 40V in the figure is greater than 0.15V, the output of the comparator U602A is at a high level and then transmitted to the control module, so as to trigger the overcurrent protection function of the control module.
Specifically, the voltage dividing unit includes a resistor R619 and a resistor R620, a first end of the resistor R619 is electrically connected to the output end of the voltage sampling module, and a second end of the resistor R619 is electrically connected to one end of the resistor R620 and an inverting input end of the comparator U602A, respectively. In this way, by setting the resistor R619 and the resistor R620 and setting specific parameter values for the two resistors, the voltage output from the voltage sampling module is divided by the resistor R619 and the resistor R620, and then a constant voltage (for example, the voltage may be set to be 2.5V) is kept and input to the inverting input terminal of the comparator U602A, where the two resistors mainly play a role in voltage division.
Specifically, the voltage stabilizing unit includes a voltage stabilizing diode ZD604, a cathode of the voltage stabilizing diode ZD604 is electrically connected to a first end of the resistor R619, and an anode of the voltage stabilizing diode ZD604 is electrically connected to the other end of the resistor R620. Thus, by providing zener diode ZD604 (e.g., a 6.2V zener diode with relatively stable characteristics), the voltage input to the inverting input of comparator U602A can be kept more stable.
It should be further noted that the voltage comparison module further includes a current-limiting filtering unit, an input end of the current-limiting filtering unit is electrically connected with an output end of the voltage sampling module, and an output end of the current-limiting filtering unit is electrically connected with an input end of the voltage dividing unit.
Specifically, the current-limiting filtering unit includes a current-limiting resistor R637 and a filter capacitor C613, a first end of the current-limiting resistor R637 is electrically connected to an output end of the voltage sampling module, a second end of the current-limiting resistor R637 is electrically connected to an input end of the voltage dividing unit, a first end of the filter capacitor C613 is electrically connected to a first end of the current-limiting resistor R637, and a second end of the filter capacitor C613 is electrically connected to a negative end of the voltage comparing unit. In this way, by providing the current limiting resistor R637 and the filter capacitor C613, the interference of the voltage input to the comparator U602A can be filtered, and the stability of the voltage input can be improved.
It should be noted that, referring to fig. 4, the control module includes a control circuit and an optocoupler unit, an input end of the optocoupler unit is electrically connected to an input end of the voltage comparison module, and an output end of the optocoupler unit is electrically connected to a control end of the control circuit. In this embodiment, the control circuit has a control chip U100, where the control chip is U100, and a control chip with a model number NCP1399A is used.
Specifically, the optocoupler unit includes a resistor R610, a resistor R100, a light emitting diode PC1A, and an optocoupler triode PC1B, where a first end of the resistor R610 is electrically connected to an input end of the voltage comparison module, a second end of the resistor R610 is electrically connected to an anode of the light emitting diode PC1A, the light emitting diode PC1A is electrically connected to the optocoupler triode PC1B, a collector of the optocoupler triode PC1B is electrically connected to one end of the resistor R100, another end of the resistor R100 is used to connect to an external VCC2, and an emitter of the optocoupler triode PC1B is electrically connected to an OVP pin of the control circuit.
In the working process, when the voltage difference between the first voltage 40V-2 of the first sampling unit and the second voltage 40V of the second sampling unit is greater than 0.15V, the output end of the comparator U602A is triggered to output a high voltage, so that the output high voltage is transmitted to the anode of the light emitting diode PC1A after passing through the zener diode ZD606, and the optocoupler unit is turned on, that is, the optocoupler transistor PC1B is turned on, so that VCC2 is output from the emitter of the optocoupler transistor PC1B to the OVP/OTP pin of the control circuit U100, thereby triggering the overcurrent protection function.
The invention also provides an overcurrent protection system, which comprises an overcurrent protection circuit and a delay protection circuit; in order to achieve the function of output end delay protection and improve the reliability and stability of the overcurrent protection system, for example, in an embodiment, referring to fig. 5, the delay protection circuit includes a positive end sampling module 500, a first comparison module 600 and a second comparison module 700, where an input end of the positive end sampling module is electrically connected to a voltage output end, an output end of the positive end sampling module is electrically connected to an input end of the first comparison module, an output end of the first comparison module is electrically connected to an input end of the second comparison module, and an output end of the second comparison module is electrically connected to the control module. The positive end sampling module is used for obtaining the high-end voltage of the power supply output end, namely outputting the voltage of the positive end; the first comparison module is used for acquiring voltages at two ends of the positive end sampling module, outputting the voltages to one input end of the second comparison module after passing through a circuit of the first comparison module, and outputting the voltages to the control module by the second comparison module; the control module is used for realizing overcurrent protection of the power supply. The second comparison module is a delay module.
Referring to fig. 2, the positive side sampling module 500 includes a resistor R212 and a resistor R213, wherein a first end of the resistor R212 is electrically connected to a positive electrode of the power output terminal, a second end of the resistor R212 is electrically connected to an input terminal of the first comparison module 600, two ends of the resistor R213 are respectively electrically connected to two ends of the resistor R212, and the first end of the resistor R212 is a sampling end of 22V-1, and the second end of the resistor R212 is a sampling end of 22V-2. Therefore, the accuracy of overcurrent detection, namely the accuracy of overcurrent sampling can be improved by arranging the high-end sampling resistor R212 and the resistor R213, so that the sampled voltage cannot be interfered by the load of the output end in the process of overcurrent protection, false triggering of an overcurrent protection circuit is avoided, the control circuit of the power supply starts the overcurrent protection work, and the printer can work normally.
The first comparison module 600 includes a voltage stabilizing unit, a first voltage dividing unit, a voltage input unit and a first comparator 600A, where an input end of the voltage stabilizing unit is electrically connected to a second end of the resistor R212, the voltage stabilizing unit is electrically connected to the first voltage dividing unit and the voltage input unit, an output end of the first voltage dividing unit is electrically connected to an inverting input end of the first comparator, another input end of the voltage input unit is electrically connected to a first end of the resistor R212, an output end of the voltage input unit is electrically connected to an in-phase input end of the first comparator, and an output end of the first comparator is electrically connected to an input end of the second comparison module 700. Therefore, the voltage input to the inverting input terminal of the first comparator can be kept at a fixed voltage value by arranging the voltage stabilizing unit, the first voltage dividing unit is used for realizing the voltage dividing function, and the voltage input unit is used for sampling at the first end of the resistor R212, inputting the sampled voltage to the non-inverting input terminal of the first comparator, and amplifying the output voltage after comparing the sampled voltage with the fixed voltage value.
Specifically, referring to fig. 6, the voltage stabilizing unit includes an integrated circuit IC600, and the integrated circuit IC600 is electrically connected to the second terminal of the resistor R212 and the output terminal of the first voltage dividing unit, respectively. The first voltage dividing unit comprises a resistor R601 and a resistor R603, wherein a first end of the resistor R601 is electrically connected with one end of the integrated circuit IC600, a second end of the resistor R601 is electrically connected with the first end of the resistor R603, a second end of the resistor R603 is electrically connected with the other end of the integrated circuit IC600, and the first end of the resistor R601 is electrically connected with the 2 pin of the first comparator U600A. The voltage input unit comprises a resistor R602, a resistor R604 and a resistor R611, wherein one end of the resistor R602 is electrically connected with one end of the integrated circuit IC600, the other end of the resistor R602 is respectively electrically connected with the resistor R604 and the resistor R611, the resistor R604 is also electrically connected with the first end of the resistor R212, and the resistor R611 is also electrically connected with the non-inverting input end of the first comparator.
The second comparing module 700 includes a discharging unit, a delay unit, a second voltage dividing unit, a voltage limiting unit and a second comparator U600B, where the discharging unit, the delay unit and the second voltage dividing unit are respectively electrically connected with the output end of the first comparing module 600, the output end of the discharging unit and the delay unit are electrically connected with the non-inverting input end of the second comparator U600B, the output end of the second voltage dividing unit is electrically connected with the inverting input end of the second comparator U600B, and the output end of the second comparator U600B is electrically connected with the control module. Therefore, by setting the delay unit, the overcurrent protection circuit has a delay function, so that when the power supply output end needs to be subjected to overcurrent protection, the overcurrent protection function is started only after the delay for 6-7 s; the discharging unit is used for realizing the discharging of the delay unit; the second voltage dividing unit is used for realizing voltage division; the voltage limiting unit is used for limiting the voltage of the second comparator to be not more than 32V, so that the comparator is prevented from being burnt out due to overlarge voltage difference, and a protection effect is achieved; the second comparator U600B is configured to compare voltages of the non-inverting input terminal and the inverting input terminal, and further output the voltages to the control module, so as to implement an overcurrent protection function.
Specifically, referring to fig. 6, the delay unit includes a capacitor C603, a capacitor C604, a resistor R607, and a resistor R627, where one end of the capacitor C603 is electrically connected to the output end of the first comparator U600A, the other end of the capacitor C603 is electrically connected to the second end of the resistor R212, the capacitor C604 is electrically connected to the output end of the first comparator U600A, the other end of the capacitor C604 is electrically connected to the second end of the resistor R212, one end of the resistor R607 is electrically connected to the voltage output end of the 40V-2, the other end of the resistor R607 is electrically connected to the capacitor C604 after passing through the resistor R627, and the resistor R627 is also electrically connected to the 5 pin of the second comparator U600B; thus, when the output terminal of the first comparator U600A outputs a high level, the capacitor C603 and the capacitor C604 are charged by the resistor R607 and the resistor R627 by 40V-2, and the obtained voltage is input to the non-inverting input terminal of the second comparator U600B.
The discharging unit comprises a diode D601 and a resistor R626, wherein the anode of the diode D601 is electrically connected with the capacitor C603, and the cathode of the diode D601 is electrically connected with the voltage output end of the 40V-2 after passing through the resistor R626. In this way, after the capacitor C603 and the capacitor C604 are fully charged, the system is also over-current protected, so that the power supply of the system is disconnected, and the voltages of the capacitor C603 and the capacitor C604 realize the discharging function through the diode D601 and the resistor R626, so as to provide preparation for the delay over-current protection again.
The second voltage dividing unit comprises a resistor R609 and a resistor R608, wherein a first end of the resistor R609 is electrically connected with the voltage output end of the 40V-2, and a second end of the resistor R609 is electrically connected with the resistor R608 and the inverting input end of the second comparator U600B respectively, so that the voltage dividing function can be realized, and the voltage is input into the second comparator U600B after the voltage is divided.
The voltage limiting unit comprises a diode ZD601 and a capacitor C605, wherein an anode of the diode ZD601 is electrically connected with a second end of the resistor R212, namely, the second end of the resistor R212 is 22V-2, a cathode of the diode ZD601 is electrically connected with a voltage output end of 40V and an anode connection end of the second comparator U600B respectively, one end of the capacitor C605 is electrically connected with an anode of the diode ZD601, and one end of the capacitor C605 is electrically connected with a cathode of the diode ZD 601. Thus, when the system is powered down, if the 22V output is fully loaded and the 40V output is empty, the voltage of 22V-2 may quickly drop to a voltage close to 0V when the power is turned on or off, and if the voltage of 40V is slower because of empty, the second comparator U600B may be damaged if the voltage of 22V is still greater than 32V or more when the voltage of 22V drops to 0V. Thus, by providing the diode ZD601, the operating voltage input to the second comparator U600B can be clamped within its safe voltage range, for example, within 24V, so as to ensure the normal operation of the second comparator U600B.
Compared with the prior art, the invention has the following advantages:
The invention relates to an overcurrent protection circuit and an overcurrent protection system, which can prevent the sampled voltage from being influenced by two or multiple output adjustment rates and the load size of each output in the overcurrent protection process by arranging a voltage sampling module in the output end of a power supply. The occurrence of false triggering of the overcurrent protection circuit is avoided, so that the control circuit of the power supply starts the overcurrent protection work, and the printer can work normally. The invention is also suitable for voltage application with output voltage higher than 32V, and solves the defect that the maximum working voltage of an operational amplifier or a comparator is only 32V.
The above embodiments represent only a few embodiments of the present invention, which are described in more detail and are not to be construed as limiting the scope of the present invention. It should be noted that it will be apparent to those skilled in the art that several variations and modifications can be made without departing from the spirit of the invention, which are all within the scope of the invention. Accordingly, the scope of protection of the present invention is to be determined by the appended claims.
Claims (6)
1. An overcurrent protection circuit, comprising: the device comprises a voltage sampling module, a differential amplification module, a voltage comparison module and a control module, wherein two input ends of the differential amplification module are respectively and electrically connected with the voltage sampling module, an output end of the differential amplification module is electrically connected with one input end of the voltage comparison module, an output end of the voltage sampling module is also electrically connected with the other input end of the voltage comparison module, and an output end of the voltage comparison module is electrically connected with the control module;
The voltage sampling module comprises a sampling resistor R202, a first end of the sampling resistor R202 is electrically connected with a first input end of the differential amplification module, and a second end of the sampling resistor R202 is electrically connected with a second input end of the differential amplification module;
The differential amplification module comprises a differential amplification unit, a first sampling unit and a second sampling unit, wherein the input end of the first sampling unit is connected with the first end of the voltage sampling module, the output end of the first sampling unit is electrically connected with the inverted input end of the differential amplification unit, the input end of the second sampling unit is connected with the second end of the voltage sampling module, the output end of the second sampling unit is electrically connected with the in-phase input end of the differential amplification unit, and the output end of the differential amplification unit is electrically connected with the voltage comparison module;
The differential amplifying unit comprises an amplifier U602B, wherein the non-inverting input end of the amplifier U602B is electrically connected with the output end of the second sampling unit, the inverting input end of the amplifier U602B is electrically connected with the output end of the first sampling unit, and the output end of the amplifier U602B is electrically connected with the input end of the voltage comparison module;
The voltage comparison module comprises a voltage comparison unit, a voltage stabilizing unit and a voltage dividing unit, wherein the input end of the voltage dividing unit is electrically connected with the output end of the voltage sampling module, the output end of the voltage dividing unit is electrically connected with the inverting input end of the voltage comparison unit, the two ends of the voltage stabilizing unit are connected with the two ends of the voltage dividing unit in parallel, the non-inverting input end of the voltage comparison unit is electrically connected with the output end of the differential amplification module, and the output end of the voltage comparison unit is output to the control module.
2. The overcurrent protection circuit according to claim 1, wherein the voltage comparison unit includes a comparator U602A and a diode D606, the non-inverting input terminal of the comparator U602A is electrically connected to the output terminal of the differential amplification module, the inverting input terminal of the comparator U602A is electrically connected to the output terminal of the voltage division unit, the output terminal of the comparator U602A is electrically connected to the anode of the diode D606, and the cathode of the diode D606 is electrically connected to the input terminal of the control module.
3. The overcurrent protection circuit of claim 1, wherein the voltage comparison module further comprises a current limiting filter unit, an input of the current limiting filter unit is electrically connected to an output of the voltage sampling module, and an output of the current limiting filter unit is electrically connected to an input of the voltage dividing unit.
4. The overcurrent protection circuit according to claim 3, wherein the current limiting filter unit includes a current limiting resistor R637 and a filter capacitor C613, a first end of the current limiting resistor R637 is electrically connected to the output terminal of the voltage sampling module, a second end of the current limiting resistor R637 is electrically connected to the input terminal of the voltage dividing unit, a first end of the filter capacitor C613 is electrically connected to the first end of the current limiting resistor R637, and a second end of the filter capacitor C613 is electrically connected to the negative terminal of the voltage comparing unit.
5. The overcurrent protection circuit according to claim 1, wherein the control module comprises a control circuit and an optocoupler unit, an input end of the optocoupler unit is electrically connected with an input end of the voltage comparison module, and an output end of the optocoupler unit is electrically connected with a control end of the control circuit.
6. An overcurrent protection system comprising the overcurrent protection circuit according to any one of claims 1 to 5.
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201811646441.3A CN109861511B (en) | 2018-12-30 | 2018-12-30 | Overcurrent protection circuit and overcurrent protection system |
| PCT/CN2019/121352 WO2020140656A1 (en) | 2018-12-30 | 2019-11-27 | Overcurrent protection circuit, and overcurrent protection system |
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| Application Number | Priority Date | Filing Date | Title |
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| CN201811646441.3A CN109861511B (en) | 2018-12-30 | 2018-12-30 | Overcurrent protection circuit and overcurrent protection system |
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| CN109861511A CN109861511A (en) | 2019-06-07 |
| CN109861511B true CN109861511B (en) | 2024-07-26 |
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| CN109861511B (en) * | 2018-12-30 | 2024-07-26 | 惠州三华工业有限公司 | Overcurrent protection circuit and overcurrent protection system |
| CN116667268B (en) * | 2022-12-15 | 2024-07-12 | 荣耀终端有限公司 | Method for preventing triggering over-current protection and electronic equipment |
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| CN209516923U (en) * | 2018-12-30 | 2019-10-18 | 惠州三华工业有限公司 | Current foldback circuit and Over Current Protection System |
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| CN102496903B (en) * | 2011-11-15 | 2014-10-29 | 深圳桑达国际电子器件有限公司 | Over-current protection circuit, power supply circuit and power supply |
| CN103259405B (en) * | 2012-02-20 | 2015-10-07 | 理光微电子株式会社 | DC-DC converter |
| CN203135403U (en) * | 2012-12-18 | 2013-08-14 | Tcl通力电子（惠州）有限公司 | Over-current protection circuit for loader |
| CN203135393U (en) * | 2013-03-05 | 2013-08-14 | 深圳Tcl新技术有限公司 | Current foldback circuit for hot swapping fittings of electronic equipment |
| CN103311878B (en) * | 2013-04-24 | 2016-03-02 | 华南理工大学 | A kind of bipolar electrical stimulation protection device |
| CN103475217B (en) * | 2013-09-06 | 2017-07-28 | 深圳Tcl新技术有限公司 | DC DC circuits and its over-current protection method |
| JP6220249B2 (en) * | 2013-12-02 | 2017-10-25 | ローム株式会社 | Switching converter and its control circuit, AC / DC converter, power adapter and electronic device |
| CN103683931B (en) * | 2013-12-27 | 2016-09-28 | 深圳市航嘉驰源电气股份有限公司 | A kind of power-switching circuit |
| CN203951161U (en) * | 2014-06-03 | 2014-11-19 | 成都嘉晨科技有限公司 | A kind of overcurrent monitoring protective circuit |
| CN105449631B (en) * | 2015-12-21 | 2019-02-19 | 山东航天电子技术研究所 | A kind of anti-latch circuit of aerospace |
| CN106787734B (en) * | 2017-02-21 | 2019-05-24 | 哈尔滨工业大学深圳研究生院 | A kind of control circuit suitable for improving cascade converter system stability |
| CN206908273U (en) * | 2017-06-26 | 2018-01-19 | 钜微电源技术（深圳）有限公司 | Source current detects protection circuit |
| CN109861511B (en) * | 2018-12-30 | 2024-07-26 | 惠州三华工业有限公司 | Overcurrent protection circuit and overcurrent protection system |
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