CN206820650U - A kind of switching power circuit - Google Patents
A kind of switching power circuit Download PDFInfo
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- CN206820650U CN206820650U CN201720539672.9U CN201720539672U CN206820650U CN 206820650 U CN206820650 U CN 206820650U CN 201720539672 U CN201720539672 U CN 201720539672U CN 206820650 U CN206820650 U CN 206820650U
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- power conversion
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- partial pressure
- resistance
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Abstract
The utility model discloses a kind of switching power circuit, has DC input, for the load connection end being connected with load positive pole and the output electric current measure end for being connected with load negative pole；Switching power circuit includes power conversion unit, pwm chip, partial pressure unit and output current sampling unit；The input of power conversion unit is connected with DC input, and the output end of power conversion unit is connected with load connection end；The pwm signal input of power conversion unit and the pwm signal output pin of pwm chip connect；The first end of output current sampling unit is connected with output electric current measure end, the second end ground connection of output current sampling unit；The first end of partial pressure unit is connected with load connection end, and the second end of partial pressure unit is connected with the first end of output current sampling unit, and the divider node of partial pressure unit and the overvoltage protection pin of pwm chip connect.By above structure, protection and lock-in circuit when the utility model can be excessive or short-circuit in load current.
Description
Technical field
It the utility model is related to electronic circuit technology field, and in particular to a kind of switching power circuit.
Background technology
At present, Switching Power Supply is widely used in television backlight circuit, but when circuit breaks down, may
There is the phenomenon of current over pulse, it is excessive to flow through the electric current of backlight LED circuit, influences LED life, can more likely cause LED to damage
It is bad.Simultaneously as backlight LED circuit is made up of multiple LED, thus when part LED occurs short-circuit, it can also flow through backlight
The electric current increase of LED circuit.However, it is not for current over pulse or load short circuits phenomenon in existing switching power circuit
Circuit is provided and is effectively protected.
Utility model content
The utility model embodiment technical problems to be solved are to provide a kind of switching power circuit, can be in load current
Protection and lock-in circuit when excessive or short-circuit.
In order to solve the above-mentioned technical problem, the utility model embodiment provides a kind of switching power circuit, the switch electricity
Source circuit has DC input, for the load connection end that be connected of load positive pole and for being connected with loading negative pole
Output electric current measure end；The switching power circuit includes power conversion unit, pwm chip, partial pressure unit and output
Current sampling unit；
The input of the power conversion unit is connected with the DC input, the output of the power conversion unit
End is connected with the load connection end；The pwm signal input of the power conversion unit and the PWM of the pwm chip
Signal output pin connects；The first end of the output current sampling unit is connected with the output electric current measure end, described defeated
Go out the second end ground connection of current sampling unit；The first end of the partial pressure unit is connected with the load connection end, the partial pressure
Second end of unit is connected with the first end of the output current sampling unit, the divider node of the partial pressure unit with it is described
The overvoltage protection pin connection of pwm chip.
In a kind of optional embodiment, the output current sampling unit includes first resistor；The first resistor
First end be connected with the first end of the output current sampling unit, the second end of the first resistor and the output current
The second end connection of sampling unit.
In a kind of optional embodiment, the partial pressure unit includes second resistance and 3rd resistor；Described second
The first end of resistance is connected with the first end of the partial pressure unit, the second end of the second resistance by the 3rd resistor with
The second end connection of the partial pressure unit, the second end of the second resistance is connected with the divider node of the partial pressure unit.
In a kind of optional embodiment, first end and the pwm chip of the output current sampling unit
Voltage Feedback pin connection.
In a kind of optional embodiment, the power conversion unit includes inductance, metal-oxide-semiconductor, diode and first
Electric capacity；The first end of the inductance is connected with the input of the power conversion unit, the second end of the inductance and described two
The anode connection of pole pipe；The negative electrode of the diode passes through first capacity earth, the negative electrode of the diode and the work(
The output end connection of rate converter unit；The drain electrode of the metal-oxide-semiconductor is connected with the second end of the inductance, the grid of the metal-oxide-semiconductor
It is connected with the pwm signal input of the power conversion unit, the source ground of the metal-oxide-semiconductor.
In a kind of optional embodiment, the power conversion circuit also includes the second electric capacity and the 4th resistance；It is described
The first end of second electric capacity is connected with the drain electrode of the metal-oxide-semiconductor, the second end of second electric capacity by the 4th resistance with
The source electrode connection of the metal-oxide-semiconductor.
In a kind of optional embodiment, the power conversion unit also has input electric cur- rent measure end, the input
Current detecting end is connected with the current detecting pin of the pwm chip；
The power conversion unit also includes the 5th resistance；The source electrode of the metal-oxide-semiconductor passes through the 5th resistance eutral grounding, institute
The source electrode of metal-oxide-semiconductor is stated to be connected with the input electric cur- rent measure end of the power conversion unit.
In a kind of optional embodiment, the switching power circuit also includes the 3rd electric capacity and the 6th resistance；Institute
The first end for stating the 3rd electric capacity is connected by the 6th resistance with the compensation controlling switch of the pwm chip, and described
The second end ground connection of three electric capacity.
Compared to prior art, a kind of switching power circuit of the utility model embodiment, the switching power circuit tool
There is DC input, for the load connection end being connected with load positive pole and the output current for being connected with load negative pole
Test side；The switching power circuit includes power conversion unit, pwm chip, partial pressure unit and output current sampling
Unit；The input of the power conversion unit is connected with the DC input, the output end of the power conversion unit
It is connected with the load connection end；The pwm signal input of the power conversion unit is believed with the PWM of the pwm chip
The connection of number output pin；The first end of the output current sampling unit is connected with the output electric current measure end, the output
The second end ground connection of current sampling unit；The first end of the partial pressure unit is connected with the load connection end, the partial pressure list
Second end of member is connected with the first end of the output current sampling unit, the divider node of the partial pressure unit and the PWM
The overvoltage protection pin connection of control chip.By above structure, the utility model embodiment is sampled by the output current
Unit, which detects, flows through the electric current of load, when electric current is excessive or during load short circuits, the partial pressure increase of the output current sampling unit,
The voltage of the divider node of the partial pressure unit is set to increase to the overvoltage protection magnitude of voltage of the pwm chip, described in control
Pwm chip stops to the metal-oxide-semiconductor output pwm signal, and then it is load supplying to stop circuit, reaches and protects and lock
The effect of circuit.
Brief description of the drawings
Fig. 1 is a kind of structural representation for switching power circuit that the utility model embodiment provides.
Embodiment
Below in conjunction with the accompanying drawing in the utility model embodiment, the technical scheme in the embodiment of the utility model is carried out
Clearly and completely describing, it is clear that described embodiment is only part of the embodiment of the present utility model, rather than all
Embodiment.Based on the embodiment in the utility model, those of ordinary skill in the art are not under the premise of creative work is made
The every other embodiment obtained, belong to the scope of the utility model protection.
Referring to Fig. 1, it is a kind of structural representation for switching power circuit that the utility model embodiment provides.This reality
A kind of switching power circuit is provided with new embodiment, the switching power circuit has DC input Vin, for bearing
Carry the load connection end Vout and the output electric current measure end a for being connected with load negative pole of positive pole connection；The switch electricity
Source circuit includes power conversion unit 1, pwm chip U, partial pressure unit 2 and output current sampling unit 3；
The input of the power conversion unit 1 is connected with the DC input Vin, the power conversion unit 1
Output end be connected with the load connection end Vout；The pwm signal input of the power conversion unit 1 is controlled with the PWM
Coremaking piece U pwm signal output pin GATE connections；The first end of the output current sampling unit 3 and the output current
Test side a connections, the second end ground connection GND of the output current sampling unit 3；The first end of the partial pressure unit 2 with it is described
Connection end Vout connections are loaded, the second end of the partial pressure unit 2 is connected with the first end of the output current sampling unit 3,
The divider node of the partial pressure unit 2 is connected with the overvoltage protection pin OVP of the pwm chip U.
The operation principle of the utility model embodiment is：
When circuit normal work, the electric current of load is flowed through in normal range (NR), passes through the output current sampling unit 3
Detection flows through the electric current of load, and now the partial pressure of the output current sampling unit 3 is in normal range (NR), the partial pressure unit 2
Divider node voltage below the overvoltage protection magnitude of voltage of the pwm chip U, pwm chip U pwm signal
Output pin GATE is kept to the output pwm signal of power conversion unit 1, and then is kept to load supplying；
When load occurs short circuit or makes electric current excessive because of fault, the electric current increase of load is flowed through, by described defeated
Go out the detection of current sampling unit 3 when flowing through the electric current of load, the partial pressure of output current sampling unit 3 increase, make the partial pressure
The voltage of the divider node of unit 2 increases and reaches pwm chip U overvoltage protection magnitude of voltage, pwm chip U PWM
Signal output pin GATE stops to the output pwm signal of power conversion unit 1, and then stops to load supplying, reaches guarantor
The effect of protection circuit.
It should be noted that when pwm chip U overvoltage protection pin OVP voltage reaches overvoltage protection magnitude of voltage
When, the pwm signal output pin GATE of the pwm chip U stops output pwm signal, i.e., described pwm chip U enters
Enter lock-out state, it is necessary to which the power end (not shown) voltage pull-down of the pwm chip U to low level could be released into lock
Determine state.
In a kind of optional embodiment, the output current sampling unit 3 includes first resistor R1；First electricity
Resistance R1 first end be connected with the first end of the output current sampling unit 3, the second end of the first resistor R1 with it is described
The second end connection of output current sampling unit 3.The first resistor R1 is used to detect the electric current for flowing through load, and according to electric current
Size produces corresponding partial pressure.
In a specific embodiment, the output current sampling unit 3 can also be the connection in series-parallel assembly of multiple resistance.
In a kind of optional embodiment, the partial pressure unit 2 includes second resistance R2 and 3rd resistor R3；It is described
Second resistance R2 first end is connected with the first end of the partial pressure unit 2, and the second end of the second resistance R2 passes through described
3rd resistor R3 is connected with the second end of the partial pressure unit 2, the second end of the second resistance R2 and the partial pressure unit 2
Divider node connects.The second resistance R2 and 3rd resistor R3 is used to carry out the output voltage for loading connection end Vout
Partial pressure, the voltage got is input to the overvoltage protection pin OVP of the pwm chip U by the divider node.
In a kind of optional embodiment, first end and the pwm chip of the output current sampling unit 3
U Voltage Feedback pin FB connections.
The Voltage Feedback pin FB of the pwm chip U is big for the partial pressure according to the output current sampling unit 3
The dutycycle of small adjustment pwm chip U pwm signal output, realizes constant current.Concrete principle is：When the output electricity
When stream sampling unit 3 detects that the electric current for flowing through load reduces, the partial pressure of the output current sampling unit 3 reduces, the PWM
Control chip U Voltage Feedback pin FB voltage reduces, the pwm signal output pin GATE outputs of the pwm chip U
Pwm signal dutycycle increase, and then increase load connection end Vout electric current；When the output current sampling unit 3
When detecting the electric current increase for flowing through load, the partial pressure increase of the output current sampling unit 3, the pwm chip U's
Voltage Feedback pin FB voltage increase, the pwm signal of the pwm signal output pin GATE outputs of the pwm chip U
Dutycycle reduces, and then reduces load connection end Vout electric current；Constant current is realized by above negative-feedback mechanism.
In a kind of optional embodiment, the power conversion unit 1 include inductance L, metal-oxide-semiconductor FET, diode D with
And the first electric capacity C1；The first end of the inductance L is connected with the input of the power conversion unit 1, and the second of the inductance L
End is connected with the anode of the diode D；The negative electrode of the diode D is grounded GND, two pole by the first electric capacity C1
Pipe D negative electrode is connected with the output end of the power conversion unit 1；The drain electrode of the metal-oxide-semiconductor FET and the second of the inductance L
End connection, the grid of the metal-oxide-semiconductor FET are connected with the pwm signal input of the power conversion unit 1, the metal-oxide-semiconductor FET
Source ground GND.
The power conversion unit 1 is BOOST converter, and the switch of the metal-oxide-semiconductor FET is controlled by the PWM controls core
The height of the pwm signal of piece U pwm signal output pin GATE outputs；The operation principle of the BOOST converter is this area
The common knowledge of technical staff, will not be described in great detail herein.
It should be noted that it is only of the present utility model a kind of preferred that the power conversion unit, which is BOOST converter,
Embodiment, it is not all of embodiment.The power conversion unit can also be isolated converter, as inverse-excitation type converts
Device.
In a kind of optional embodiment, the power conversion circuit also includes the second electric capacity C2 and the 4th resistance R4；
The first end of the second electric capacity C2 is connected with the drain electrode of the metal-oxide-semiconductor FET, and the second end of the second electric capacity C2 passes through described
4th resistance R4 is connected with the source electrode of the metal-oxide-semiconductor FET.The second electric capacity C2 and the 4th resistance R4 composition with it is described
RC absorption circuits in parallel metal-oxide-semiconductor FET, effectively reduce the metal-oxide-semiconductor caused electromagnetic interference during high-speed switch.
In a kind of optional embodiment, the power conversion unit 1 also has input electric cur- rent measure end, the input
Current detecting end is connected with the current detecting pin CS of the pwm chip U；
The power conversion unit 1 also includes the 5th resistance R5；The source electrode of the metal-oxide-semiconductor FET passes through the 5th resistance
R5 is grounded GND, and the source electrode of the metal-oxide-semiconductor FET is connected with the input electric cur- rent measure end of the power conversion unit 1.
The 5th resistance R5 is used for the conducting electric current for detecting the metal-oxide-semiconductor FET, and electric current flows through the 5th resistance R5 productions
Raw certain partial pressure is simultaneously transferred to the current detecting pin CS of the pwm chip U, enable the pwm chip U according to
The input voltage of the current detecting pin CS constantly adjusts the dutycycle of pwm signal, steady load connection end Vout output
Electric current.Its concrete operating principle is：If the input voltage of the current detecting pin CS is with being higher than the pwm chip U's
Compensate controlling switch COMP voltage, then the pwm signal that the pwm signal output pin GATE of the pwm chip U is exported
Dutycycle reduces；If the input voltage of the current detecting pin CS and the compensation controlling switch less than the pwm chip U
The dutycycle increase of COMP voltage, the then pwm signal of the pwm signal output pin GATE outputs of the pwm chip U.
In a kind of optional embodiment, the switching power circuit also includes the 3rd electric capacity C3 and the 6th resistance
R6；The compensation controlling switch that the first end of the 3rd electric capacity C3 passes through the 6th resistance R6 and pwm chip U
COMP connections, the second end ground connection GND of the 3rd electric capacity C3.The 3rd electric capacity C3 and the 6th resistance R6 compositions RC
Loop compensation circuit, realize quick, accurate, stable loop adjustment.
Compared to prior art, a kind of switching power circuit of the utility model embodiment, the switching power circuit tool
There is DC input, for the load connection end being connected with load positive pole and the output current for being connected with load negative pole
Test side；The switching power circuit includes power conversion unit, pwm chip, partial pressure unit and output current sampling
Unit；The input of the power conversion unit is connected with the DC input, the output end of the power conversion unit
It is connected with the load connection end；The pwm signal input of the power conversion unit is believed with the PWM of the pwm chip
The connection of number output pin；The first end of the output current sampling unit is connected with the output electric current measure end, the output
The second end ground connection of current sampling unit；The first end of the partial pressure unit is connected with the load connection end, the partial pressure list
Second end of member is connected with the first end of the output current sampling unit, the divider node of the partial pressure unit and the PWM
The overvoltage protection pin connection of control chip.By above structure, the utility model embodiment is sampled by the output current
Unit, which detects, flows through the electric current of load, when electric current is excessive or during load short circuits, the voltage rise of the output current sampling unit,
The voltage of the divider node of the partial pressure unit is increased to the overvoltage protection voltage of the pwm chip, control the PWM
Control chip stops to the metal-oxide-semiconductor output pwm signal, and then it is load supplying to stop circuit, reaches and protects and lock electricity
The effect on road.
Described above is preferred embodiment of the present utility model, it is noted that for the ordinary skill of the art
For personnel, on the premise of the utility model principle is not departed from, some improvements and modifications can also be made, these are improved and profit
Decorations are also considered as the scope of protection of the utility model.
Claims (8)
- A kind of 1. switching power circuit, it is characterised in that the switching power circuit have DC input, for load The load connection end of positive pole connection and the output electric current measure end for being connected with load negative pole；The switching power circuit bag Include power conversion unit, pwm chip, partial pressure unit and output current sampling unit；The input of the power conversion unit is connected with the DC input, the output end of the power conversion unit with Load connection end connection；The pwm signal input of the power conversion unit and the pwm signal of the pwm chip Output pin connects；The first end of the output current sampling unit is connected with the output electric current measure end, the output electricity Flow the second end ground connection of sampling unit；The first end of the partial pressure unit is connected with the load connection end, the partial pressure unit The second end be connected with the first end of the output current sampling unit, the divider node of the partial pressure unit and the PWM are controlled The overvoltage protection pin connection of coremaking piece.
- 2. switching power circuit as claimed in claim 1, it is characterised in that the output current sampling unit includes the first electricity Resistance；The first end of the first resistor is connected with the first end of the output current sampling unit, and the second of the first resistor End is connected with the second end of the output current sampling unit.
- 3. switching power circuit as claimed in claim 1, it is characterised in that the partial pressure unit includes second resistance and the Three resistance；The first end of the second resistance is connected with the first end of the partial pressure unit, and the second end of the second resistance leads to Cross the 3rd resistor to be connected with the second end of the partial pressure unit, the second end and the partial pressure unit of the second resistance Divider node connects.
- 4. switching power circuit as claimed in claim 1, it is characterised in that the first end of the output current sampling unit with The Voltage Feedback pin connection of the pwm chip.
- 5. switching power circuit as claimed in claim 1, it is characterised in that the power conversion unit includes inductance, MOS Pipe, diode and the first electric capacity；The first end of the inductance is connected with the input of the power conversion unit, the inductance The second end be connected with the anode of the diode；The negative electrode of the diode passes through first capacity earth, two pole The negative electrode of pipe is connected with the output end of the power conversion unit；The drain electrode of the metal-oxide-semiconductor is connected with the second end of the inductance, The grid of the metal-oxide-semiconductor is connected with the pwm signal input of the power conversion unit, the source ground of the metal-oxide-semiconductor.
- 6. switching power circuit as claimed in claim 5, it is characterised in that the power conversion circuit also includes the second electric capacity With the 4th resistance；The first end of second electric capacity is connected with the drain electrode of the metal-oxide-semiconductor, and the second end of second electric capacity passes through 4th resistance is connected with the source electrode of the metal-oxide-semiconductor.
- 7. the switching power circuit as described in claim 5 or 6, it is characterised in that the power conversion unit also has input Current detecting end, the input electric cur- rent measure end are connected with the current detecting pin of the pwm chip；The power conversion unit also includes the 5th resistance；The source electrode of the metal-oxide-semiconductor is described by the 5th resistance eutral grounding The source electrode of metal-oxide-semiconductor is connected with the input electric cur- rent measure end of the power conversion unit.
- 8. switching power circuit as claimed in claim 1, it is characterised in that the switching power circuit also includes the 3rd electric capacity And the 6th resistance；The first end of 3rd electric capacity is controlled by the compensation of the 6th resistance and the pwm chip Pin connects, the second end ground connection of the 3rd electric capacity.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201720539672.9U CN206820650U (en) | 2017-05-12 | 2017-05-12 | A kind of switching power circuit |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201720539672.9U CN206820650U (en) | 2017-05-12 | 2017-05-12 | A kind of switching power circuit |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN206820650U true CN206820650U (en) | 2017-12-29 |
Family
ID=60756433
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN201720539672.9U Active CN206820650U (en) | 2017-05-12 | 2017-05-12 | A kind of switching power circuit |
Country Status (1)
| Country | Link |
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| CN (1) | CN206820650U (en) |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN109658878A (en) * | 2019-03-04 | 2019-04-19 | 合肥惠科金扬科技有限公司 | The backlight drive circuit and display device of display panel |
| CN112904925A (en) * | 2019-11-19 | 2021-06-04 | 杭州海康消防科技有限公司 | Load driving and protection circuit |
-
2017
- 2017-05-12 CN CN201720539672.9U patent/CN206820650U/en active Active
Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN109658878A (en) * | 2019-03-04 | 2019-04-19 | 合肥惠科金扬科技有限公司 | The backlight drive circuit and display device of display panel |
| CN109658878B (en) * | 2019-03-04 | 2024-01-09 | 重庆惠科金扬科技有限公司 | Backlight driving circuit of display panel and display device |
| CN112904925A (en) * | 2019-11-19 | 2021-06-04 | 杭州海康消防科技有限公司 | Load driving and protection circuit |
| CN112904925B (en) * | 2019-11-19 | 2022-07-29 | 杭州海康消防科技有限公司 | Load driving and protection circuit |
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| TR01 | Transfer of patent right |
Effective date of registration: 20180315 Address after: Kezhu road high tech Industrial Development Zone, Guangzhou city Guangdong province 510663 No. 192 3 310 floor Co-patentee after: Guangzhou CVT Electronics Technology Co., Ltd. Patentee after: Guangzhou Kun Electronic Technology Co. Ltd. Address before: Kezhu road high tech Industrial Development Zone, Guangzhou city Guangdong province 510663 No. 192 3 310 floor Patentee before: Guangzhou Kun Electronic Technology Co. Ltd. |
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| TR01 | Transfer of patent right |