CN102005748B - Isolation type positive-negative output constant current protective device - Google Patents
Isolation type positive-negative output constant current protective device Download PDFInfo
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- CN102005748B CN102005748B CN 201010537268 CN201010537268A CN102005748B CN 102005748 B CN102005748 B CN 102005748B CN 201010537268 CN201010537268 CN 201010537268 CN 201010537268 A CN201010537268 A CN 201010537268A CN 102005748 B CN102005748 B CN 102005748B
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Abstract
The invention relates to an isolation type positive-negative output constant current protective device electrically connected with current output side phase, comprising a sampling circuit, an operation amplifying circuit electrically connected with the sampling circuit, an optical coupler isolation circuit and a primary side control circuit which is electrically connected with the operation amplifying circuit by virtue of the optical coupler isolation circuit; wherein the sampling circuit comprises a positive terminal sampling device electrically connected with positive terminal output phase and a negative terminal sampling device electrically connected with negative terminal output phase; the sampling circuit samples positive and negative output currents simultaneously, the sample signals are input into the operation amplifying circuit, the operation amplifying circuit judges whether output current reaches protection threshold, if yes, the operation amplifying circuit transmits the signal to the primary side control circuit by virtue of the optical coupler isolation circuit, and the primary side control circuit controls the output current to be in constant state. The invention can realize sampling on positive and negative output currents at secondary side, long-term constant current protection can be realized without damaging circuit while realizing positive and negative outputs, and structure is simple, thus being convenient for integration.
Description
Technical field
The present invention relates to a kind of power stage short circuit and current protection technology, definite says, relates to a kind of isolation type positive-negative output constant current protective device that can be applicable in isolation type switch power, motor-driven and the power amplifier.
Background technology
In Switching Power Supply, motor-driven and power amplifier, need to adopt overcurrent protective device to prevent the circuit damage that overcurrent and short circuit cause.For power supply, motor-driven and the power amplifier of isolated form, generally by former limit input peak current is detected, thereby when appearring in output, short circuit or overcurrent can make the peak current of the input trigger protection circuit working that increases sharply.When adopting this protective device; because primary current is taken a sample can not be accurately and in time variation and the state of the inferior limit of reflection output current; device need to bear very large peak current when short circuit or overcurrent occurring; reliability to circuit has infringement, can not effectively and protect output for a long time.
Summary of the invention
The purpose of this invention is to provide a kind of isolation type positive-negative output constant current protective device of can be effectively and for a long time output being protected.
For achieving the above object, the technical solution used in the present invention is:
A kind of isolation type positive-negative output constant current protective device, described isolation type positive-negative output constant current protective device and electric current output limit is electrically connected, the operational amplification circuit that described isolation type positive-negative output constant current protective device comprises sample circuit, be electrically connected with described sample circuit, optical coupling isolation circuit, the former limit control circuit that is electrically connected by described optical coupling isolation circuit and described operational amplification circuit;
Described electric current output limit comprises anode output, negative terminal output, described sample circuit comprise the anode sampler that is electrically connected with anode output, with the negative terminal sampler that negative terminal output is electrically connected, described sample circuit can be sampled simultaneously to anode output and negative terminal output;
The protection threshold value of initialization circuit; described sample circuit aligns negative output current and samples simultaneously; and the sampled signal of the gained of will sampling is inputted described operational amplification circuit; described operational amplification circuit is judged described output current and whether is reached the protection threshold value; when reaching the protection threshold value; described operational amplification circuit is passed to described former limit control circuit by described optical coupling isolation circuit with signal, and control circuit control in described former limit limits described output current in constant current state.
Preferably, described anode sampler comprises the first sample resistance, and described the first sample resistance is sampled to the anode output current.
Preferably, described negative terminal sampler comprises the second sample resistance, and described the second sample resistance is sampled to the negative terminal output current.
Preferably, described former limit control circuit recently limits described output current in constant current state by the by-pass cock duty.
Preferably, when described output current reaches the protection threshold value, described operational amplification circuit output low level.
Because technique scheme is used, the present invention compared with prior art has following advantages:
1, the present invention takes a sample to electric current on inferior limit, the long-time constant current protection that can realize exporting and do not damage circuit.
2, the present invention can align negative output current and take a sample simultaneously protection when can realize positive negative output.
3, circuit structure of the present invention is simple, is convenient to integrated.
Description of drawings
Accompanying drawing 2 is the sample circuit figure of isolation type positive-negative output constant current protective device of the present invention.
Embodiment
The invention will be further described below in conjunction with embodiment shown in the drawings:
Embodiment one: the positive-negative output constant current protective device that is used for isolated form DC/DC Switching Power Supply.
Shown in accompanying drawing 1.
A kind of isolation type positive-negative output constant current protective device; this isolation type positive-negative output constant current protective device and electric current output limit is electrically connected, the operational amplification circuit that isolation type positive-negative output constant current protective device comprises sample circuit, be electrically connected with sample circuit, optical coupling isolation circuit, the former limit control circuit that is electrically connected by optical coupling isolation circuit and operational amplification circuit.
The protection threshold value of initialization circuit; sample circuit aligns negative output current and samples simultaneously; and with the sampled signal of gained input operational amplification circuit; operational amplification circuit is judged output current and whether is reached the protection threshold value; when reaching the protection threshold value; the operational amplification circuit output low level, and by optical coupling isolation circuit signal is passed to former limit control circuit, control circuit control in former limit limits output current in constant current state.
Shown in accompanying drawing 2 and accompanying drawing 3.
Electric current output limit comprises anode output, negative terminal output, sample circuit comprise the anode sampler that is electrically connected with anode output, with the negative terminal sampler that negative terminal output is electrically connected, sample circuit can be sampled simultaneously to anode output and negative terminal output; The anode sampler comprises the first sample resistance RS1, and the negative terminal sampler comprises the second sample resistance RS2, and the resistance of these two sample resistances is all very little.
The protection threshold value of initialization circuit, isolation type positive-negative output constant current protective device aligns output current by RS1 and takes a sample, and by RS2 negative output current is taken a sample.After the sampling, the value of RS1 sampling is sent to operational amplification circuit from CS1, and the value of RS2 sampling is sent to operational amplification circuit from CS2.
Because this sample circuit can align simultaneously negative output current and takes a sample simultaneously, therefore, when overcurrent or short circuit all appear in V+ and V-, can realize simultaneously the long-time constant current protection of positive negative output.
The value of taking a sample as RS1 surpasses the protection threshold value that sets; when being V+ output overcurrent or short circuit; increase to the electric current of CS1 from the GND RS1 that flows through; thereby the voltage that CS1 is ordered will reduce; the such positive input terminal lower voltage of operational amplifier U1, after reaching default protection threshold value, the output end voltage of operational amplifier U1 reduces; the luminous tube electric current of optocoupler U2 increases, thereby reduces the level of former limit control circuit.
In like manner; the value of taking a sample as RS2 surpasses the protection threshold value that sets; be V-output overcurrent or short circuit; will increase to the electric current of GND from the CS2 RS2 that flows through, thereby the CS2 point voltage uprises, operational amplifier U1 negative input end voltage uprises; after reaching default protection threshold value; the output end voltage of operational amplifier U1 reduces, and the luminous tube electric current of optocoupler U2 increases, thereby reduces the level of former limit control circuit.
Former limit control circuit can be realized the constant current of output is controlled by various ways, and in the present embodiment, former limit control circuit is realized the constant current of output is protected by reducing duty cycle of switching.After the level of former limit control circuit reduced, former limit control circuit UCC1800 reduced the transfer power of supply convertor by switch control end by-pass cock duty ratio, realized the constant current defencive function of the positive negative output of output.
Above-described embodiment only is explanation technical conceive of the present invention and characteristics, and its purpose is to allow the personage who is familiar with technique can understand content of the present invention and according to this enforcement, can not limit protection scope of the present invention with this.All equivalences that Spirit Essence is done according to the present invention change or modify, and all should be encompassed within protection scope of the present invention.
Claims (3)
1. isolation type positive-negative output constant current protective device, it is characterized in that: described isolation type positive-negative output constant current protective device and electric current output limit is electrically connected, the operational amplification circuit that described isolation type positive-negative output constant current protective device comprises sample circuit, be electrically connected with described sample circuit, optical coupling isolation circuit, the former limit control circuit that is electrically connected by described optical coupling isolation circuit and described operational amplification circuit;
Described electric current output limit comprises anode output, negative terminal output, described sample circuit comprise the anode sampler that is electrically connected with anode output, with the negative terminal sampler that negative terminal output is electrically connected, described sample circuit can be sampled simultaneously to anode output and negative terminal output; Described anode sampler comprises the first sample resistance, and described the first sample resistance is sampled to the anode output current; Described negative terminal sampler comprises the second sample resistance, and described the second sample resistance is sampled to the negative terminal output current;
The protection threshold value of initialization circuit, described sample circuit aligns negative output current and samples simultaneously, and the sampled signal of the gained of will sampling is inputted described operational amplification circuit, described operational amplification circuit is judged described output current and whether is reached the protection threshold value, when reaching the protection threshold value, described operational amplification circuit is passed to described former limit control circuit by described optical coupling isolation circuit with signal, and control circuit control in described former limit limits described output current in constant current state;
When the value of described the first sample resistance sampling surpasses the protection threshold value that sets, described the first sample resistance of flowing through from ground increases to the electric current of the positive input terminal of described operational amplification circuit, thereby make the lower voltage of the positive input terminal of described operational amplification circuit, after reaching default protection threshold value, the output end voltage of described operational amplification circuit reduces, the electric current of described optical coupling isolation circuit increases, thereby reduces the level of former limit control circuit;
When the value of described the second sample resistance sampling surpasses the protection threshold value that sets; increase to the electric current on ground from the negative input end of described operational amplification circuit described the second sample resistance of flowing through; thereby the negative input end voltage of described operational amplification circuit is uprised; after reaching default protection threshold value; the output end voltage of described operational amplification circuit reduces; the electric current of described optical coupling isolation circuit increases, thereby reduces the level of former limit control circuit.
2. isolation type positive-negative output constant current protective device according to claim 1, it is characterized in that: described former limit control circuit recently limits described output current in constant current state by the by-pass cock duty.
3. isolation type positive-negative output constant current protective device according to claim 1 is characterized in that: when described output current reaches the protection threshold value, and described operational amplification circuit output low level.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN 201010537268 CN102005748B (en) | 2010-11-10 | 2010-11-10 | Isolation type positive-negative output constant current protective device |
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN 201010537268 CN102005748B (en) | 2010-11-10 | 2010-11-10 | Isolation type positive-negative output constant current protective device |
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| Publication Number | Publication Date |
|---|---|
| CN102005748A CN102005748A (en) | 2011-04-06 |
| CN102005748B true CN102005748B (en) | 2013-09-18 |
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| Application Number | Title | Priority Date | Filing Date |
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| CN 201010537268 Expired - Fee Related CN102005748B (en) | 2010-11-10 | 2010-11-10 | Isolation type positive-negative output constant current protective device |
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Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN201044418Y (en) * | 2007-04-28 | 2008-04-02 | 蔡俊东 | Constant-current control power supply |
| CN201360365Y (en) * | 2009-02-26 | 2009-12-09 | 青岛海信电器股份有限公司 | Power supply control circuit and projector scope with the circuit |
| CN101790265A (en) * | 2009-12-31 | 2010-07-28 | 中国科学院广州电子技术研究所 | Multichannel constant current control circuit |
Family Cites Families (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP4662003B2 (en) * | 2001-02-09 | 2011-03-30 | ミツミ電機株式会社 | AC adapter output terminal short protection circuit |
-
2010
- 2010-11-10 CN CN 201010537268 patent/CN102005748B/en not_active Expired - Fee Related
Patent Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN201044418Y (en) * | 2007-04-28 | 2008-04-02 | 蔡俊东 | Constant-current control power supply |
| CN201360365Y (en) * | 2009-02-26 | 2009-12-09 | 青岛海信电器股份有限公司 | Power supply control circuit and projector scope with the circuit |
| CN101790265A (en) * | 2009-12-31 | 2010-07-28 | 中国科学院广州电子技术研究所 | Multichannel constant current control circuit |
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| CN102005748A (en) | 2011-04-06 |
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