CN213023324U - Current detection device and switching power supply - Google Patents
Current detection device and switching power supply Download PDFInfo
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- CN213023324U CN213023324U CN202021790406.1U CN202021790406U CN213023324U CN 213023324 U CN213023324 U CN 213023324U CN 202021790406 U CN202021790406 U CN 202021790406U CN 213023324 U CN213023324 U CN 213023324U
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Abstract
The utility model discloses a current detection device and switching power supply, the device includes: the current sampling part is arranged in an output loop of the switching power supply and is used for sampling the output current of the switching power supply; the first amplifying part is connected with the current sampling part and used for acquiring voltage difference between two ends of the current sampling part and amplifying the voltage difference to acquire a first amplified voltage; and the second amplification part is connected with the first amplification part and used for amplifying the first amplification voltage, acquiring a current detection voltage and sending the current detection voltage to the switching power supply. The utility model discloses it is high, the driving force is strong to detect the precision to and can effective reduce cost.
Description
Technical Field
The utility model relates to the field of electronic technology, concretely relates to current detection device and switching power supply.
Background
A switching power supply is a power supply capable of performing power conversion, wherein a dc switching power supply is a typical switching power supply for supplying a dc power to a power consumption device. The safety in use of the direct-current switching power supply is the most important problem while the power supply requirement of the electric equipment is met, if the output power of the direct-current switching power supply is too large, the direct-current switching power supply is not in accordance with safety standards and safety standards, and serious potential safety hazards exist, so that the output power of the direct-current switching power supply is limited, and the output power is guaranteed not to exceed a safety range.
In the prior art, the purpose of limiting the output power is achieved by limiting the output current of the power supply, and the detection of the output current of the power supply is a key link. The current power supply output current detection mode has the following problems: the special amplifier is often adopted to achieve certain detection precision and driving capability of the switch power supply output current control device, and the cost is high.
Disclosure of Invention
The utility model discloses to the proposition of above problem, and provide one kind and detect the precision height, the driving force is strong to and the current detection device that can effective reduce cost, still provide a switching power supply who possesses this kind of current detection device simultaneously.
The utility model discloses a technical means be: provided is a current detection device including:
the current sampling part is arranged in an output loop of the switching power supply and is used for sampling the output current of the switching power supply;
the first amplifying part is connected with the current sampling part and used for acquiring voltage difference between two ends of the current sampling part and amplifying the voltage difference to acquire a first amplified voltage; and
and the second amplifying part is connected with the first amplifying part and used for amplifying the first amplifying voltage, acquiring a current detection voltage and sending the current detection voltage to the switching power supply.
The utility model discloses another technical means who adopts is: provided is a switching power supply including: the current detection device provided by the above one technical means; the switching power supply is provided with an adjusting end, and the current detection device is connected with the adjusting end of the switching power supply; the output current of the switching power supply changes along with the change of the input voltage of the adjusting end.
Since the technical scheme is used, the utility model provides a current detection device and switching power supply, adopt current sampling portion to sample switch power supply output current, at first acquire and enlarge current sampling portion both ends voltage difference through first enlarger, then further amplify the processing and output current detection voltage give switching power supply to the first amplified voltage of first enlarger output through the second enlarger, use ordinary amplifier device alright in order to reach higher detection precision, can effectively reduce cost, can realize the stronger drive to switch power supply output current control device through the configuration of two enlargers.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, it is obvious that the drawings in the following description are only some embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to these drawings without creative efforts.
Wherein:
FIG. 1 is a block diagram of a current detection device and a switching power supply according to an embodiment;
FIG. 2 is a schematic circuit diagram of a current sensing device and a switching power supply in one embodiment;
fig. 3 is a comparative example diagram of the current detection device.
In the figure: 1. the current detection device comprises a current detection device 2, a controllable precise voltage stabilizing source 3, an output loop 4, a load 11, a current sampling part 12, a first amplification part 13, a second amplification part 111, a high voltage end 112 and a low voltage end.
Detailed Description
In order to make the objects, technical solutions and technical effects of the present invention clearer, the present invention will be described in detail with reference to the accompanying drawings and specific embodiments. It should be understood that the detailed description and specific examples, while indicating the present invention, are given by way of illustration and not limitation. In the case of conflict, the embodiments and features of the embodiments of the present invention can be combined with each other.
The present invention provides a current detection device 1, which in one embodiment, as shown in fig. 1, may include a current sampling portion 11, a first amplification portion 12, and a second amplification portion 13. The current sampling unit 11 is provided in the output circuit 3 of the switching power supply and samples the output current of the switching power supply. The switching power supply is a direct current power supply capable of performing power conversion, the output loop 3 of the switching power supply is an output loop 3 capable of supplying power to a load 4, when the output end of the switching power supply comprises a power end and a ground end, the output loop 3 of the switching power supply is a loop between the power end and the ground end, and the load 4 can be arranged on the output loop 3 of the switching power supply. The output current of the switching power supply is the current flowing through the output circuit 3, and when the output power of the switching power supply is limited, the output current of the switching power supply can be limited. When the output current of the switching power supply flows through the output circuit 3, the output current also flows through the current sampling unit 11 provided in the output circuit 3, the current sampling unit 11 can sample the output current, and a voltage difference is formed between two ends of the current sampling unit 11 flowing through the output current.
The first amplifying section 12 is connected to the current sampling section 11, and is configured to obtain a voltage difference across the current sampling section 11, and amplify the voltage difference to obtain a first amplified voltage. The second amplifying part 13 is connected to the first amplifying part 12, and is configured to amplify the first amplified voltage, obtain a current detection voltage, and send the current detection voltage to the switching power supply. The voltage difference across the current sampling unit 11 flowing through the output current is amplified by the first amplifying unit 12 to obtain the first amplified voltage, and is amplified by the second amplifying unit 13 to obtain the current detection voltage. The switching power supply can further adjust the output current based on the received current detection voltage, so that a closed loop process of sampling and controlling the output current of the switching power supply is formed, and the limiting purpose of further adjusting the reduction of the output current according to the current detection voltage when the output current of the switching power supply is too large can be achieved.
In the embodiment, the first amplifying part 12 is used for acquiring the voltage difference between two ends of the current sampling part 11, so as to further realize the acquisition of the output current of the switching power supply, and meanwhile, the two amplifying parts are configured to gradually amplify the voltage difference and drive the switching power supply output current control device, so that higher detection precision and stronger driving capability can be achieved through the common amplifying device, and the cost can be effectively reduced.
In one embodiment, as shown in fig. 2, the current sampling unit 11 may be a sampling resistor R2, the current sampling unit 11 and the load 4 are connected in series in the output circuit 3 of the switching power supply, and the sampling resistor R2 is capable of sampling the output current of the switching power supply flowing through itself. When the load 4 is a variable load, the change of the load 4 will cause the change of the output current of the switching power supply, when the load 4 is heavy, the output current of the switching power supply is larger, and when the load 4 is light, the output current of the switching power supply is smaller. Referring to fig. 2, R11 represents the load 4. The two ends of the current sampling portion 11 are a high voltage end 111 and a low voltage end 112, respectively, the high voltage end 111 and the low voltage end 112 form the voltage difference, the potential of the high voltage end 111 is higher than the potential of the low potential end, for example, the high voltage end 111 is closer to the power supply end VCC of the switching power supply than the low potential end.
In one embodiment, as shown in fig. 2, the first amplifying section 12 may include a first input resistor R3, a second input resistor R4, a third input resistor R1, a first feedback resistor R5, a first pull-down resistor R6, a first output resistor R7, and a first operational amplifier U1A. The first input resistor R3 and the second input resistor R4 are connected in series to form a voltage divider circuit, two ends of the voltage divider circuit are respectively connected to the high voltage terminal 111 and a ground terminal GND of the switching power supply, specifically, one end of the first input resistor R3 is connected to the high voltage terminal 111, the other end of the first input resistor R3 is connected to one end of the second input resistor R4, and the other end of the second input resistor R4 is connected to the ground terminal GND of the switching power supply. The voltage divider circuit can obtain the voltage of the high-voltage end 111 of the current sampling unit 11, divide the voltage of the high-voltage end 111, and input the divided voltage to the non-inverting input terminal of the first operational amplifier U1A. For example, referring to fig. 2, at this time, the voltage of the high voltage end 111 is the output voltage VCC of the switching power supply, and the voltage input to the non-inverting input end of the first operational amplifier U1A by the voltage dividing circuit is VCC [ R4/(R3+ R4) ]. The non-inverting input end of the first operational amplifier U1A is connected with the voltage division point of the voltage division circuit. The inverting input terminal of the first operational amplifier U1A is connected to the low voltage terminal 112 through the third input resistor R1. Two ends of the first feedback resistor R5 are respectively connected with the inverting input end and the output end of the first operational amplifier U1A. The output terminal of the first operational amplifier U1A is connected to the ground GND of the switching power supply through the first pull-down resistor R6, and outputs the first amplified voltage to the second amplifying unit 13 through the first output resistor R7. The voltage at the low-voltage end 112 of the current sampling unit 11 is divided by the third input resistor R1 and the first feedback resistor R5, and then input to the inverting input terminal of the first operational amplifier U1A. Exemplarily, referring to fig. 2, in a case that a voltage difference Vd exists across the sampling resistor R2, a voltage input to the inverting input terminal of the first operational amplifier U1A is [ VCC-Vd ] (R5)/(R1+ R5) ]. For example, as shown in fig. 2, the first operational amplifier U1A may adopt an operational amplifier chip of a model LM358, and of course, the first operational amplifier U1A may also adopt other operational amplifier chips without rail-to-rail output characteristics, for example, LM258, LM324, LM2904, and the like.
In one embodiment, as shown in fig. 2, the high voltage terminal 111 may be connected to a power terminal VCC of the switching power supply, and the low voltage terminal 112 is connected to a ground terminal GND of the switching power supply through the load 4. The resistance of the sampling resistor R2 may be smaller than the resistance of the first input resistor R3 by 3 orders of magnitude, for example, if the resistance of the first input resistor R3 is k Ω level, the resistance of the sampling resistor R2 is m Ω level, and exemplarily, referring to fig. 2, the resistance of the first input resistor R3 is 20k Ω, and the resistance of the sampling resistor R2 is 220m Ω.
In one embodiment, the first amplified voltage may be a first preset multiple of the voltage difference, the first preset multiple is equal to a ratio of a resistance value of the first feedback resistor R5 to a resistance value of the third input resistor R1, and the first amplifying part 12 may amplify the voltage difference formed by the current sampling part 11 by R5/R1 and output the amplified voltage to the second amplifying part 13. Illustratively, referring to fig. 2, the first amplifying section constitutes a negative feedback differential input structure. The first preset multiple may be R5/R1 ═ 56k Ω/20k Ω ═ 2.8. Further, the first amplification voltage is lower than the power supply voltage of the first operational amplifier U1A, the power supply voltage of the first operational amplifier U1A is used for providing the operating power supply for the first operational amplifier U1A, for example, the first operational amplifier U1A may also be directly powered by the switching power supply, the first amplification voltage output by the first operational amplifier U1A is lower than the power supply voltage, and the first operational amplifier U1A does not need to have rail-to-rail output characteristics.
In one embodiment, as shown in fig. 2, the second amplifying section 13 may include a second pull-down resistor R10, a second feedback resistor R9, a second output resistor R12, and a second operational amplifier U1B. The non-inverting input terminal of the second operational amplifier U1B is configured to receive the first amplified voltage. Two ends of the second feedback resistor R9 are respectively connected with the inverting input end and the output end of the second operational amplifier U1B. The inverting input terminal of the second operational amplifier U1B is connected to the ground GND of the switching power supply through the second pull-down resistor R10. The output terminal of the second operational amplifier U1B sends the current detection voltage to the switching power supply. For example, as shown in fig. 2, the second operational amplifier U1B may adopt an operational amplifier chip of a model LM358, and of course, the second operational amplifier U1B may also adopt other operational amplifier chips without rail-to-rail output characteristics, for example, LM258, LM324, LM2904, and the like. The first operational amplifier U1A and the second operational amplifier U1B may also use the same dual channel op-amp.
In one embodiment, the current detection voltage may be a second preset multiple of the first amplification voltage. The second preset multiple is equal to a ratio of a sum of resistances of the second feedback resistor R9 and the second pull-down resistor R10 to a resistance of the second pull-down resistor R10, and the second amplifying unit 12 is capable of amplifying (R9+ R10)/R10 times the first amplified voltage output by the first amplifying unit 12 and then sending the amplified voltage as the current detection voltage to the switching power supply. Exemplarily, referring to fig. 2, the second preset multiple may be (R9+ R10)/R10 ═ 9.1k Ω +5k Ω)/5k Ω ═ 2.82. Further, the current detection voltage may be lower than the supply voltage of the second operational amplifier U1B, the supply voltage of the second operational amplifier U1B is used for supplying an operating power supply to the second operational amplifier U1B, for example, the second operational amplifier U1B may also be directly supplied by the switching power supply, the current detection voltage output by the second operational amplifier U1B is lower than the supply voltage, and the second operational amplifier U1B does not need to have a rail-to-rail output characteristic.
The utility model also provides a switching power supply, in an embodiment, as with reference to fig. 1 and 2, switching power supply can include: the current detection device according to any one of the above embodiments. The switching power supply is provided with an adjusting end, and the current detection device is connected with the adjusting end of the switching power supply. The output current of the switching power supply changes along with the change of the input voltage of the adjusting end. Specifically, the adjusting terminal may be a sampling feedback terminal of the output current of the switching power supply, and if the input voltage of the adjusting terminal changes, it is equivalent to that the output current of the switching power supply changes. The current detection device is connected to the adjustment terminal of the switching power supply, so that the current detection voltage output by the second amplification unit 13 is used as the input voltage of the adjustment terminal, and the output current of the switching power supply can be changed according to the change of the current detection voltage, thereby achieving the purpose of controlling and limiting the output current of the switching power supply. Further, the adjusting terminal may be a reference electrode of a controllable precision voltage regulator 2 included in the switching power supply, as shown in fig. 2, the controllable precision voltage regulator 2 may be a TL431 serving as the TL431 of the controllable precision voltage regulator 2, an internal reference voltage is 2.5VDC, and the controllable precision voltage regulator 2 may adjust and control an output current of the switching power supply based on a comparison condition between the current detection voltage received by the reference electrode and the internal reference voltage.
In one embodiment, the switching power supply may be a flyback switching power supply, and the switching power supply may also be another dc switching power supply.
To better illustrate the technical effects of the present invention, such as high detection accuracy, strong driving capability, and effectively reducing cost, a comparison example of the switching power supply output current detection device shown in fig. 3 is provided, referring to fig. 3, in order to ensure the detection accuracy of the switching power supply output current and the driving of the switching power supply output control device, the switching power supply output current is first amplified by a current mirror circuit to form a sampling voltage, and then the sampling voltage is input to an operational amplifier, because the sampling voltage formed after the amplification by the current mirror circuit is higher, a common operational amplifier without rail-to-rail characteristics cannot input such a high sampling voltage, and in order to ensure the stable amplification gain of the operational amplifier and avoid oscillation, a single operational amplifier alone cannot effectively amplify the switching power supply output current, therefore, the switching power supply output current detection apparatus shown in fig. 3 needs to use a specific operational amplifier having rail-to-rail characteristics for both input and output, and to cooperate with a current mirror circuit, so as to achieve the purpose of sampling and controlling the output current of the switching power supply. Such as the model LMC7101BIM5 operational amplifier of fig. 3, is more costly and has fewer options. And that shows in fig. 2 the utility model discloses a switching power supply output current detection device only needs ordinary operational amplifier to arrange switching power supply output current's collection network simultaneously, alright in order to realize the purpose of switching power supply output current sample and control. Exemplarily, as the embodiment of the present invention in fig. 2, the voltage difference at both ends of the current sampling unit 11 is directly collected and inputted to the first amplification unit 12, the collected output current of the switching power supply is not amplified before the first amplification unit 12, the voltage difference with a lower voltage value is inputted to the first amplification unit 12 by using a negative feedback differential input structure, without the need that the first amplification unit 12 has a rail-to-rail characteristic, and the two-stage amplification of the first amplification unit 12 and the second amplification unit 13 is simultaneously adopted to achieve the effective amplification and the sampling detection precision of the output current of the switching power supply, thereby achieving the purpose of sampling and controlling the output current of the switching power supply.
The above description is only for the preferred embodiment of the present invention, but the scope of the present invention is not limited thereto, and any person skilled in the art can substitute or change the technical solution and the inventive concept of the present invention within the technical scope of the present invention. Furthermore, although specific terms are employed herein, they are used in a generic and descriptive sense only and not for purposes of limitation.
Claims (10)
1. A current sensing device, the device comprising:
the current sampling part is arranged in an output loop of the switching power supply and is used for sampling the output current of the switching power supply;
the first amplifying part is connected with the current sampling part and used for acquiring voltage difference between two ends of the current sampling part and amplifying the voltage difference to acquire a first amplified voltage; and
and the second amplifying part is connected with the first amplifying part and used for amplifying the first amplifying voltage, acquiring a current detection voltage and sending the current detection voltage to the switching power supply.
2. The current detection device according to claim 1,
the current sampling part is a sampling resistor, and the current sampling part and a load are connected in series in an output loop of the switching power supply;
the two ends of the current sampling part are respectively a high-voltage end and a low-voltage end, and the high-voltage end and the low-voltage end form the voltage difference.
3. The current detection device according to claim 2,
the first amplification section includes: the circuit comprises a first input resistor, a second input resistor, a third input resistor, a first feedback resistor, a first pull-down resistor, a first output resistor and a first operational amplifier;
the first input resistor and the second input resistor are connected in series to form a voltage division circuit, and two ends of the voltage division circuit are respectively connected with the high-voltage end and the grounding end of the switching power supply; the non-inverting input end of the first operational amplifier is connected with a voltage division point of the voltage division circuit;
the inverting input end of the first operational amplifier is connected with the low-voltage end through the third input resistor; two ends of the first feedback resistor are respectively connected with the inverting input end and the output end of the first operational amplifier;
the output end of the first operational amplifier is connected with the ground end of the switching power supply through the first pull-down resistor, and outputs the first amplified voltage to the second amplifying part through the first output resistor.
4. The current detection device according to claim 3,
the high-voltage end is connected with a power end of the switching power supply, and the low-voltage end is connected with a grounding end of the switching power supply through the load;
the resistance value of the sampling resistor is smaller than that of the first input resistor by 3 orders of magnitude.
5. The current detection device according to claim 3,
the first amplified voltage is a first preset multiple of the voltage difference, and the first preset multiple is equal to the ratio of the resistance value of the first feedback resistor to the resistance value of the third input resistor;
the first amplification voltage is lower than a supply voltage of the first operational amplifier.
6. The current detection device according to claim 1, wherein the second amplification section includes: the second pull-down resistor, the second feedback resistor, the second output resistor and the second operational amplifier;
the non-inverting input end of the second operational amplifier is used for receiving the first amplified voltage; two ends of the second feedback resistor are respectively connected with the inverting input end and the output end of the second operational amplifier; the inverting input end of the second operational amplifier is connected with the grounding end of the switching power supply through the second pull-down resistor; and the output end of the second operational amplifier sends the current detection voltage to the switching power supply.
7. The current detection device according to claim 6, wherein the current detection voltage is a second predetermined multiple of the first amplification voltage, the second predetermined multiple being equal to a ratio of a sum of the resistances of the second feedback resistor and the second pull-down resistor to the resistance of the second pull-down resistor;
the current detection voltage is lower than a supply voltage of the second operational amplifier.
8. A switching power supply, characterized in that the switching power supply comprises: the current detection device according to any one of claims 1 to 7; the switching power supply is provided with an adjusting end, and the current detection device is connected with the adjusting end of the switching power supply; the output current of the switching power supply changes along with the change of the input voltage of the adjusting end.
9. The switching power supply according to claim 8, wherein the switching power supply comprises a controllable precision voltage-stabilizing source, and the adjusting terminal is a reference pole of the controllable precision voltage-stabilizing source.
10. The switching power supply according to claim 8 or 9, wherein the switching power supply is a flyback switching power supply.
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| Application Number | Priority Date | Filing Date | Title |
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| CN202021790406.1U CN213023324U (en) | 2020-08-24 | 2020-08-24 | Current detection device and switching power supply |
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| CN202021790406.1U CN213023324U (en) | 2020-08-24 | 2020-08-24 | Current detection device and switching power supply |
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Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN113866662A (en) * | 2021-09-26 | 2021-12-31 | 石家庄通合电子科技股份有限公司 | Switching power supply output current detection circuit and switching power supply |
| CN117411449A (en) * | 2023-12-14 | 2024-01-16 | 浙江地芯引力科技有限公司 | Current sampling amplifying circuit, chip and electronic equipment |
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2020
- 2020-08-24 CN CN202021790406.1U patent/CN213023324U/en active Active
Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN113866662A (en) * | 2021-09-26 | 2021-12-31 | 石家庄通合电子科技股份有限公司 | Switching power supply output current detection circuit and switching power supply |
| CN113866662B (en) * | 2021-09-26 | 2024-07-12 | 石家庄通合电子科技股份有限公司 | Switch power supply output current detection circuit and switch power supply |
| CN117411449A (en) * | 2023-12-14 | 2024-01-16 | 浙江地芯引力科技有限公司 | Current sampling amplifying circuit, chip and electronic equipment |
| CN117411449B (en) * | 2023-12-14 | 2024-04-05 | 浙江地芯引力科技有限公司 | Current sampling amplifying circuit, chip and electronic equipment |
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