CN205753367U - A kind of power protecting circuit - Google Patents
A kind of power protecting circuit Download PDFInfo
- Publication number
- CN205753367U CN205753367U CN201620086081.6U CN201620086081U CN205753367U CN 205753367 U CN205753367 U CN 205753367U CN 201620086081 U CN201620086081 U CN 201620086081U CN 205753367 U CN205753367 U CN 205753367U
- Authority
- CN
- China
- Prior art keywords
- unit
- voltage
- feedback
- electric current
- pull
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Active
Links
Landscapes
- Protection Of Static Devices (AREA)
Abstract
A kind of power protecting circuit, including current control unit, voltage feedback unit and electric current pull-up unit；Described voltage feedback unit is connected to described current control unit, described voltage feedback unit obtains the feedback voltage of output voltage and feeds back to described current control unit, and described current control unit utilizes described feedback voltage to control described current control unit and adjusts output electric current；Described electric current pull-up unit connects the feedback end of described voltage feedback unit, and described electric current pull-up unit provides pull-up current to described voltage feedback unit, is used for judging that the feedback end of described voltage feedback unit is the most short-circuit.
Description
Technical field
This utility model relates to a kind of power circuit, particularly to a kind of power protecting circuit.
Background technology
In constant voltage output power supply circuit, output feedback end FB, by divider resistance R1 and R2 sampling and outputting voltage, by adjusting output electric current, makes the reference voltage in feedback end FB voltage and current control unit equal, thus adjust output voltage, make it stable at predeterminated voltage.
As it is shown in figure 1, constant voltage output power supply circuit 100 includes current control unit 11 and voltage feedback unit 12, voltage feedback unit 12 is in series by the first resistance R1 and the second resistance R2, and the common point FB of the first resistance R1 and the second resistance R2 is output voltage VoutFeedback end, output voltage feedback end FB is connected to current control unit.Current control unit 11 includes that the second operational amplifier U2, the first input end of the second operational amplifier U2 are connected to feedback end FB, and the second input connects the second reference signal Vref2。Vref2With feedback voltage VFBCompare, carry out control circuit according to comparative result, it is achieved constant voltage exports.
But when output loading short circuit, export feedback voltage VFBIt is about 0V, owing to current control unit samples feedback voltage VFBLess than the second reference signal Vref2, output electric current can increase to the maximum output current of constant voltage output power supply circuit 100.Due to output voltage when load short circuits close to 0, although output electric current reach maximum output current, its output can also in normal range of operation, constant voltage output power supply circuit can't cause because power consumption is excessive damage.
Utility model content
The purpose of this utility model is to provide a kind of power protecting circuit, when solving the voltage feedback unit short circuit of constant voltage output power supply circuit, the problem that circuit damages.
For achieving the above object, this utility model provides a kind of power protecting circuit, including current control unit, voltage feedback unit and electric current pull-up unit；
Described voltage feedback unit is connected to described current control unit, described voltage feedback unit obtains the feedback voltage of output voltage and feeds back to described current control unit, and described current control unit utilizes described feedback voltage to control described current control unit and adjusts output electric current；
Described electric current pull-up unit connects the feedback end of described voltage feedback unit, and described electric current pull-up unit provides pull-up current for described voltage feedback unit, it is judged that the feedback end of described voltage feedback unit is the most short-circuit.
Optionally; described power protecting circuit also includes adjustment unit; described adjustment unit input connects the feedback end of described voltage feedback unit, and is adjusted the pull-up current of described electric current pull-up unit according to described feedback voltage, thus judges that the feedback end of voltage feedback unit is the most short-circuit.
Optionally, described adjustment unit includes that the first operational amplifier, the first input end of described first operational amplifier receive the first reference signal, and the second input connects described feedback voltage, and described first operational amplifier output terminal connects described electric current pull-up unit.
Optionally, the first input end of described current control unit connects the second reference signal, and the voltage of described first reference signal is less than the voltage of described second reference signal.
Optionally, described electric current pull-up unit is composed in series by nmos pass transistor and power supply；The grid of described nmos pass transistor connects the outfan of described first operational amplifier, and source electrode connects described feedback voltage, and drain electrode connects power supply outfan.
Optionally, described electric current pull-up unit includes power supply and the switching tube of series connection.
Optionally, described electric current pull-up unit also includes the current-limiting resistance connected with described switching tube；Described power supply is constant-current source.
Optionally, the 4th resistance is accessed between feedback end and the pull-up current unit of voltage feedback unit.
Compared with prior art, the technical program has the advantage that
This utility model provides a kind of power protecting circuit, including current control unit, voltage feedback unit and electric current pull-up unit；Described voltage feedback unit is connected to described current control unit, described voltage feedback unit obtains the feedback voltage of output voltage and feeds back to described current control unit, and described current control unit utilizes described feedback voltage to control described current control unit and adjusts output electric current；Described electric current pull-up unit connects the feedback end of described voltage feedback unit, described electric current pull-up unit provides pull-up current for described voltage feedback unit, if the feedback end voltage of described voltage feedback unit constantly raises along with the carrying out of charging process, the feedback end of the most described voltage feedback unit is not short-circuited；Even if if be electrically charged, described feedback end voltage is consistently lower than level threshold value, the feedback end short circuit of the most described voltage feedback unit.Judged by short-circuit-type, perform different protection act, effectively increase the reliability of circuit.
Accompanying drawing explanation
Fig. 1 is the structural representation of prior art constant voltage output power supply circuit；
Fig. 2 is this utility model first embodiment power protecting circuit structural representation；
Fig. 3 is this utility model the second embodiment power protecting circuit structural representation；
Fig. 4 is this utility model the 3rd embodiment power protecting circuit structural representation；
Fig. 5 is this utility model the 4th embodiment power protecting circuit structural representation；
Fig. 6 is this utility model the 5th embodiment power protecting circuit structural representation；
Fig. 7 is this utility model sixth embodiment power protecting circuit structural representation.
Detailed description of the invention
As shown in Figure 1, in prior art, load 20 short circuit, constant voltage output power supply circuit 100 exports its maximum output current, but the maximum output current of constant voltage output power supply circuit can't be the biggest, and output voltage when load short circuits close to 0, constant voltage output power supply circuit will be caused to damage because of overpower.
But, when the feedback end (FB end) of voltage feedback unit is shorted to ground, namely during the first resistance R1 short circuit, output control circuit is still considered output short-circuit, and output electric current also can reach the maximum output current of constant voltage output power supply circuit.Due to load not short circuit, now output raises much larger than output during normal work, output voltage, and output voltage cannot be stablized at predeterminated voltage, thus causes constant voltage output power supply circuit or load to damage.
Based on this, this utility model provides a kind of power protecting circuit, is described in detail below in conjunction with specific embodiment and accompanying drawing:
As in figure 2 it is shown, in one embodiment, power protecting circuit includes current control unit 11, voltage feedback unit 12 and electric current pull-up unit 13；
Voltage feedback unit is composed in series by the first resistance R1 and the second resistance R2, and their common point FB end is the feedback end of output voltage.
Current control unit includes the second operational amplifier U2, and its first input end connects the second reference signal Vref2, the second input is connected to output voltage feedback end, according to the feedback voltage V of feedback endFBWith the constant voltage output that the comparative result of the second reference signal controls whole power protecting circuit 10.
Electric current pull-up unit is also connected to output voltage feedback end, and is charged to the first resistance R1 in voltage feedback unit；Feedback voltage V after chargingFBChange: if VFBAll the time close to level threshold value, then first resistance R1 short circuit, wherein level threshold value be pre-set, relatively low magnitude of voltage, such as a 0.1V；Concrete, when level threshold value is ratio the first resistance R1 short circuit, after electric current pull-up unit provides pull-up current to described first resistance, the slightly higher magnitude of voltage of the magnitude of voltage that can reach of feedback end FB.
Specific works principle is as follows:
In a certain moment, electric current pull-up unit 13 gives the first resistance R1 charging (i.e. electric current pull-up unit 13 provides pull-up current to R1) of voltage feedback unit 12；If R1 short circuit is abnormal, then the voltage of feedback end FB still can be the lowest, less than level threshold value.And during without short circuit exception, due to the charging of electric current pull-up unit 13, the voltage of feedback end FB can be essentially pulled up to a definite value.Thus, it is possible to judge that the feedback end of voltage feedback unit is the most short-circuit；If short-circuit, power protecting circuit 10 makes corresponding protection act: concrete it may be that stop to load 20 output electric current by controlling the main switch of current control unit.
During in order to prevent from starting, the damage that the feedback end short circuit of voltage feedback unit causes, when power protecting circuit starts, control electric current pull-up unit 13 and work, i.e. to the first resistance R1 charging；If short-circuit, then feedback end FB voltage is close to 0, and consistently lower than level threshold value；If not short circuit, feedback end FB voltage can be essentially pulled up to a definite value.By detecting the voltage V of feedback end FBFB, it is possible to judge whether the feedback end of voltage feedback unit 12 exists short circuit.
But, if electric current pull-up unit 13 the most persistently gives the first resistance R1 charging, the voltage feedback unit sampling to output voltage can be affected, power protecting circuit 10 loses pressure-keeping functions, causes output voltage unstable.
After solving system start-up, the short-circuit conditions of voltage feedback unit 12 also can be judged by power protecting circuit, in another embodiment, also includes adjustment unit 14, sees Fig. 3:
Adjustment unit 14 has 2 inputs and 1 outfan, and first input end connects the first reference signal Vref1, the second input connects the feedback end of voltage feedback unit 12, and outfan connects the control end of described switching tube；The output signal of adjustment unit 14 is the control signal of electric current pull-up unit 13.Electric current pull-up unit 13 receives described control signal to regulate the output electric current of self.
Concrete, electric current pull-up unit 13 is in series by power supply Vd and switching tube, and switching tube can be transistor, it is also possible to be audion；The grid of transistor or the base stage of audion are the input of electric current pull-up unit, and the outfan of adjustment unit 14 is connected to described grid or base stage.
Specific works principle is as follows:
When normally working, VFB=Vref2, the output voltage V of power protecting circuitout=Vref2* the control signal of (R1+R2)/R1 adjustment unit 14 output is not enough to drive electric current pull-up unit 13 to work; so; the electric current of electric current pull-up circuit is 0, and electric current pull-up unit does not charges to voltage feedback unit, does not affect the work of power protecting circuit normal feedback control loop.
When load short circuits, VFB<Vref1, the control signal of adjustment unit 14 output drives electric current pull-up unit 13, and electric current pull-up unit gives the first resistance R1 charging, along with the carrying out of charging, the voltage at the R1 two ends i.e. voltage V of feedback end FBFBMore and more higher, finally it is conditioned and Vref1Equal, now the output electric current I1 of electric current pull-up unit 13 is certain certain value, I1=Vref1/(R1//R2)；
When the feedback end short circuit of voltage feedback unit, during the i.e. first resistance R1 short circuit, feedback end FB voltage is 0, and the control signal of adjustment unit 14 output reaches maximum drive voltage, drives electric current pull-up unit, makes the output electric current of electric current pull-up unit reach maximum.But even if the output electric current of electric current pull-up unit 13 reaches maximum, feedback end FB voltage is still close to 0, less than level threshold value, it is impossible to reach Vref1。
Therefore the feedback end short circuit of load short circuits or voltage feedback unit can by judging the output electric current of electric current pull-up unit, be distinguished；The feedback end short circuit of load short circuits or voltage feedback unit can also be distinguished by the control signal of electric current pull-up circuit；Feedback end voltage can also be detected judge:
When load short circuits, the electric current of electric current pull-up unit is certain certain value, and its control signal is also adjusted to certain value, feedback end voltage VFBAlso it is certain certain value；
And when the feedback end short circuit of voltage feedback unit, the output electric current of electric current pull-up circuit and control signal are adjusted by ultimate value, and feedback end voltage VFBAll the time close to 0, less than level threshold value.
So, feedback end two kinds of situations of short circuit of load 20 short circuit and voltage feedback unit 12 when having distinguished work, according to different short-circuit conditions, power protecting circuit makes different protection act, particularly as follows:
During load short circuits, export maximum current；Or output maximum current a period of time, quit work a period of time, then export maximum current a period of time；
During the first resistance R1 short circuit, circuit stops to load output electric current, but voltage feedback unit and current control unit the most normally work: specifically can be realized by the duty controlling the main switch of current control unit.
When the first resistance R1 short circuit releases, owing to there being electric current to flow to the first resistance R1 from switching tube, feedback end FB voltage can raise, and the electric current flowing through switching tube can reduce, therefore can be by detection VFBOr the output electric current of electric current pull-up unit determines when the first resistance R1 short circuit and releases, then recover to load output electric current；So when the first resistance R1 short circuit, output voltage VoutDo not rise to control more than voltage, cause power circuit or load to damage.
The 3rd embodiment as shown in Figure 4, described adjustment unit 14 includes the first operational amplifier U1, and described switching tube is N MOS transistor M1, and the source electrode of nmos pass transistor M1 is connected to feedback end FB, grid connects the outfan of the first operational amplifier U1, and drain electrode connects described power supply Vd.Specific works principle is as follows:
When normally working, VFB=Vref2, output voltage Vout=Vref2*(R1+R2)/R1.The positive input terminal of the first operational amplifier U1 is described first input end, connects the first reference voltage Vref1, wherein 0Vref1<Vref2.Therefore, the negative input end voltage V of the first operational amplifier U1FBMore than positive input terminal voltage Vref1, the first operational amplifier U1 output low level, less than the minimum drive voltage of electric current pull-up unit, nmos pass transistor M1 turns off.
When load short circuits, VFB＜ Vref1, the first operational amplifier U1 exports high level, and more than the minimum drive voltage of electric current pull-up unit, nmos pass transistor M1 is open-minded, and electric current pull-up unit output electric current, feedback end FB voltage is adjusted to Vref1, by the electric current I1=V of nmos pass transistor M1ref1/(R1//R2)；
When the first resistance R1 short circuit, feedback end FB voltage is 0, and the voltage of the first operational amplifier U1 output is maximum, and the control voltage of electric current pull-up unit reaches maximum drive voltage, can be very big, at least above I1 by the electric current I2 of nmos pass transistor M1.
Therefore can be by judging the electric current of nmos pass transistor M1, distinguish load short circuits and the situation of the first resistance R1 short circuit, load short circuits and the first resistance R1 short circuit can also be distinguished: when the grid voltage of metal-oxide-semiconductor M1 is adjusted to certain value, load short circuits by the grid voltage of metal-oxide-semiconductor M1；And when the grid voltage of metal-oxide-semiconductor M1 is ceiling voltage, the first resistance R1 short circuit.
When the first resistance R1 short circuit, if being not intended to flow through the electric current of metal-oxide-semiconductor M1, this electric current can be very big, even power supply Vd can be dragged down.So adding current-limiting function in electric current pull-up unit 13: connect on power supply Vd and metal-oxide-semiconductor M1 series arm the 3rd resistance R3 again, as shown in Figure 5.In other embodiments, excessive in order to limit the electric current flowing through nmos pass transistor M1, it is also possible to power supply to be set to current source Id, the most as shown in Figure 6.
In another embodiment of the present utility model, when the second reference signal Vref2With output voltage close to time, the upper divider resistance R2 of voltage feedback unit be much smaller than lower divider resistance R1.The electric current of pull-up current unit when load short circuits and FB short circuit all can reach maximum current, it is thus possible to load short circuits judges into FB short circuit, thus stops to load output electric current.In order to prevent above-mentioned phenomenon, between the feedback end FB and pull-up current unit of voltage feedback unit, access the 4th resistance R4, as shown in Figure 7.When making load short circuits, the feedback end short circuit of voltage feedback unit will not be judged as.
This utility model power protecting circuit in accordance with the above additionally provides a kind of current protection method, particularly as follows:
During circuit start, electric current pull-up unit works, and provides electric current to voltage feedback unit；
Detection voltage feedback unit feedback end voltage VFBIf less than level threshold value, being then judged as the short circuit of described voltage feedback unit, current control unit stops to load output electric current；Otherwise, circuit normally starts.
This utility model additionally provides a kind of method that can judge short-circuit-type after on startup and normally working, particularly as follows:
By feedback voltage VFBCompare with described first reference signal；
If described feedback voltage VFBMore than described first reference signal Vref1, described adjustment unit output low-voltage, described electric current pull-up unit does not provide pull-up current；
If described feedback voltage is less than described first reference signal, described adjustment unit output voltage provides pull-up current to described voltage feedback unit higher than the minimum drive voltage of described electric current pull-up unit, described electric current pull-up unit according to the size of described adjustment unit output voltage；
Output voltage or the size of described pull-up current according to described adjustment unit judge short-circuit-type；
If described adjustment unit output voltage reaches maximum drive voltage or pull-up current reaches maximum pull-up current, then it it is the feedback end short circuit of voltage feedback unit；Otherwise, for load short circuits.
According to described short-circuit-type, perform different protection act.
Concrete protection act is: when the feedback end short circuit of voltage feedback unit, and described protection act is for stopping to described load output electric current, until the feedback end short circuit of described voltage feedback unit releases；
Or, when load short circuits, described protection act is that main circuit loads output electric current for described load output electric current or stopping to described by phased manner.After being judged as load short circuits, the circuit of the feedback end short-circuit protection of all participation voltage feedback unit does not affect the work of other circuit, such as adjusts circuit, electric current pull-up circuit.Implementing of all protection act can be by the control realization of the main switch to current control unit.
Although this utility model is open as above with preferred embodiment; but it is not for limiting this utility model; any those skilled in the art are without departing from spirit and scope of the present utility model; technical solutions of the utility model are made possible variation and amendment by the method and the technology contents that may be by the disclosure above; therefore; every content without departing from technical solutions of the utility model; any simple modification, equivalent variations and the modification made above example according to technical spirit of the present utility model, belongs to the protection domain of technical solutions of the utility model.
Claims (8)
1. a power protecting circuit, including current control unit, voltage feedback unit, it is characterised in that also include electric current pull-up unit；
Described voltage feedback unit is connected to described current control unit, described voltage feedback unit obtains the feedback voltage of output voltage and feeds back to described current control unit, and described current control unit utilizes described feedback voltage to control described current control unit and adjusts output electric current；
Described electric current pull-up unit connects the feedback end of described voltage feedback unit, and described electric current pull-up unit provides pull-up current for described voltage feedback unit, it is judged that the feedback end of described voltage feedback unit is the most short-circuit.
2. power protecting circuit as claimed in claim 1; it is characterized in that; also include adjustment unit; described adjustment unit input connects the feedback end of described voltage feedback unit; and according to described feedback voltage, the pull-up current of described electric current pull-up unit is adjusted, thus judge that the feedback end of voltage feedback unit is the most short-circuit.
3. power protecting circuit as claimed in claim 2; it is characterized in that; described adjustment unit includes the first operational amplifier; the first input end of described first operational amplifier receives the first reference signal; second input connects described feedback voltage, and described first operational amplifier output terminal connects described electric current pull-up unit.
4. power protecting circuit as claimed in claim 3, it is characterised in that the first input end of described current control unit connects the second reference signal, and the voltage of described first reference signal is less than the voltage of described second reference signal.
5. power protecting circuit as claimed in claim 3, it is characterised in that described electric current pull-up unit is composed in series by nmos pass transistor and power supply；The grid of described nmos pass transistor connects the outfan of described first operational amplifier, and source electrode connects described feedback voltage, and drain electrode connects power supply outfan.
6. power protecting circuit as claimed in claim 1, it is characterised in that described electric current pull-up unit includes power supply and the switching tube of series connection.
7. power protecting circuit as claimed in claim 6, it is characterised in that described electric current pull-up unit also includes the current-limiting resistance connected with described switching tube；
Described power supply is constant-current source.
8. the power protecting circuit as described in any one of claim 1-7, it is characterised in that access the 4th resistance between the feedback end and pull-up current unit of voltage feedback unit.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201620086081.6U CN205753367U (en) | 2016-01-28 | 2016-01-28 | A kind of power protecting circuit |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201620086081.6U CN205753367U (en) | 2016-01-28 | 2016-01-28 | A kind of power protecting circuit |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN205753367U true CN205753367U (en) | 2016-11-30 |
Family
ID=57373671
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN201620086081.6U Active CN205753367U (en) | 2016-01-28 | 2016-01-28 | A kind of power protecting circuit |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN205753367U (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN105514944A (en) * | 2016-01-28 | 2016-04-20 | 杰华特微电子（张家港）有限公司 | Power protection circuit and method |
-
2016
- 2016-01-28 CN CN201620086081.6U patent/CN205753367U/en active Active
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN105514944A (en) * | 2016-01-28 | 2016-04-20 | 杰华特微电子（张家港）有限公司 | Power protection circuit and method |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| CN105514944A (en) | Power protection circuit and method | |
| CN203481783U (en) | Short circuit and overcurrent protection circuit and mass production test equipment | |
| CN103036196B (en) | Over-pressure safety device and method | |
| CN203911743U (en) | Electronic device and capacitor discharge circuit thereof | |
| CN105445529A (en) | Brown-out detection circuit having sequential control function | |
| CN203839985U (en) | Cell discharge overcurrent protection circuit | |
| CN102790516A (en) | Feedback clamping power metal oxide semiconductor (MOS) pipe drive circuit for power supply management | |
| CN102916460A (en) | Power supply control system and semiconductor integrated circuit | |
| CN206074715U (en) | A kind of direct current power-fail detection circuit | |
| CN109890115B (en) | Intelligent lamp control system and flashing control circuit thereof | |
| CN108322030A (en) | A kind of novel discharge circuit and method | |
| CN205753367U (en) | A kind of power protecting circuit | |
| CN207368636U (en) | A kind of constant pressure output short circuit protection circuit of self recovery | |
| CN207336682U (en) | Load the detection circuit and grafting port and electric appliance of insertion | |
| CN203984377U (en) | One is with soft start and turn-off switching circuit fast | |
| CN203747779U (en) | Power tube drive circuit and direct-current solid state power controller | |
| CN113098103A (en) | Power-down discharge circuit and method and power management system | |
| CN206272903U (en) | A kind of LED linear constant-current circuit for having output short circuit protection function | |
| WO2021088259A1 (en) | Control system and method for power backup system | |
| CN108599100A (en) | A kind of ON-OFF control circuit and load switch | |
| CN101153880A (en) | Negative voltage detector | |
| CN114050710B (en) | Switching power supply circuit | |
| CN113691116B (en) | Power supply controller start control system | |
| CN101916991A (en) | Absorption circuit for restraining impact current | |
| CN108696113A (en) | A kind of Switching Power Supply shutdown delay circuit |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| C14 | Grant of patent or utility model | ||
| GR01 | Patent grant | ||
| EE01 | Entry into force of recordation of patent licensing contract |
Assignee: Jevat Microelectronics (Hangzhou) Co., Ltd. Assignor: Jevat Microelectronics (Zhangjiagang) Co., Ltd. Contract record no.: 2017330000069 Denomination of utility model: Power source protection circuit and LED lamp Granted publication date: 20161130 License type: Exclusive License Record date: 20170524 |