CN204046886U - Led constant current circuit - Google Patents
Led constant current circuit Download PDFInfo
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- CN204046886U CN204046886U CN201420495789.8U CN201420495789U CN204046886U CN 204046886 U CN204046886 U CN 204046886U CN 201420495789 U CN201420495789 U CN 201420495789U CN 204046886 U CN204046886 U CN 204046886U
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Abstract
The utility model provides a kind of LED constant current circuit, comprise voltage reference source circuit, overvoltage crowbar, constant-current circuit double operational chip (U1), described constant-current circuit comprises MOSFET pipe (Q1), described voltage reference source circuit is for generation of three road reference voltages, one road reference voltage is used for double operational chip (U1) operating voltage, another road reference voltage is used for overvoltage crowbar reference voltage, last road reference voltage is used for constant-current circuit reference voltage, described overvoltage crowbar is used for comparing with reference voltage and exporting low and high level control MOSFET by detecting input voltage and manage (Q1) and turn off, described constant-current circuit is used for being compared with reference voltage by testing circuit electric current exporting low and high level and regulating MOSFET to manage (Q1) output current.The beneficial effects of the utility model are: circuit of the present utility model is simple, cost is low, efficiency is high, without EMI problem and constant current accuracy is high, temperature drift is little.
Description
Technical field
The utility model relates to electronic circuit field, particularly relates to LED constant current circuit.
Background technology
Mostly low-voltage LED constant-current circuit is DC-DC change-over circuit in the market, there is following defect:
1. efficiency is low: only have about 90% when 24V and following power voltage supply;
2. cost is high: DC-DC change-over circuit is generally made up of parts such as control chip, MOSFET pipe, energy storage inductor, EMI original papers, and circuit is complicated, and cost is high;
3. easily there is EMI problem: DC-DC change-over circuit, because using high-frequency switch circuit, easily has EMI problem.
Utility model content
In order to solve the problems of the prior art, the utility model provides a kind of LED constant current circuit.
The utility model provides a kind of LED constant current circuit, comprise voltage reference source circuit, overvoltage crowbar, constant-current circuit, double operational chip, described constant-current circuit comprises MOSFET pipe, described voltage reference source circuit is for generation of three road reference voltages, one road reference voltage is used for double operational chip operating voltage, another road reference voltage is used for overvoltage crowbar reference voltage, last road reference voltage is used for constant-current circuit reference voltage, described overvoltage crowbar is used for comparing with reference voltage and exporting low and high level control MOSFET pipe by detecting input voltage and turn off, described constant-current circuit is used for being compared with reference voltage by testing circuit electric current exporting low and high level and regulating MOSFET pipe output current
As further improvement of the utility model; described voltage reference source circuit comprises voltage stabilizing chip, the first resistance, the second resistance, the 3rd resistance, the 4th resistance, the 5th resistance; described first resistance one end is connected to VCC1; K pin and the resistance of the described first resistance other end and described voltage stabilizing chip are connected to VCC; R pin and the 3rd resistance of the described second resistance other end and voltage stabilizing chip are connected to VREF2, and the described 3rd resistance other end and described 4th resistance and described 5th resistance are connected to VREF; Described 4th resistance and described 5th resistance other end ground connection, the A pin ground connection of described voltage stabilizing chip; 5 pin of described double operational chip are connected with described 3rd resistance, the 4th resistance, the 5th resistance respectively.
As further improvement of the utility model, described overvoltage crowbar comprises the 8th resistance, 9th resistance, tenth resistance, 4th electric capacity, triode, the amplifier modules A part of double operational chip internal, described 9th resistance respectively with 3 pin of described double operational chip, tenth resistance, described 4th electric capacity connects, described tenth resistance other end ground connection, described 4th electric capacity other end ground connection, 2 pin of described double operational chip are connected with the R pin of voltage stabilizing chip, described 8th resistance one end is connected with 1 pin of described double operational chip, the described 8th resistance other end is connected with the B pin of described triode, the C pin of described triode is connected with the G pin of MOSFET pipe, the E pin ground connection of described triode.
As further improvement of the utility model, described constant-current circuit comprises the 6th resistance, 7th resistance, 11 resistance, second electric capacity, MOSFET manages, the amplifier module B of double operational chip internal, described 7th resistance one end is connected with 6 pin of described double operational chip and described second electric capacity respectively, the described 7th resistance other end respectively with the described second electric capacity other end, described 11 resistance, the S pin of described MOSFET pipe connects, described resistance other end ground connection, described voltage reference source circuit is connected with 5 pin of described double operational chip, described 6th resistance one end is connected with 7 pin of described double operational chip, the described 6th resistance other end is connected with the G pin of described MOSFET pipe, the D pin of described MOSFET pipe is connected with output.
As further improvement of the utility model; this LED constant current circuit also comprises the diode as anti-reverse protection diode; described diode cathode is connected with power supply both positive and negative polarity; described diode cathode powers to whole constant-current circuit; described diode cathode is connected to VCC1; described 9th resistance one end is connected with described diode cathode, and the described 9th resistance other end is connected with 3 pin of described double operational chip, the tenth resistance, described 4th electric capacity respectively.
As further improvement of the utility model, this LED constant current circuit also comprises the 5th electric capacity, MOSFET pipe S pin described in described 5th electric capacity one termination, described another termination MOSFET pipe of 5th electric capacity D pin.
As further improvement of the utility model, this LED constant current circuit also comprises the first electric capacity, described first electric capacity one termination power supply positive pole, another termination power supply negative pole of described first electric capacity.
As further improvement of the utility model, this LED constant current circuit also comprises the 3rd electric capacity, 8 pin of double operational chip described in described 3rd electric capacity one termination, described 3rd electric capacity other end ground connection.
As further improvement of the utility model, the K pin of described voltage stabilizing chip is connected with 8 pin of described double operational chip.
The beneficial effects of the utility model are: circuit of the present utility model is simple, cost is low, efficiency is high, without EMI problem and constant current accuracy is high, temperature drift is little.
Accompanying drawing explanation
Fig. 1 is circuit diagram of the present utility model.
Embodiment
As shown in Figure 1; the utility model discloses a kind of LED constant current circuit, comprise voltage reference source circuit, overvoltage crowbar, constant-current circuit, diode D1, described diode D1 is as anti-reverse protection diode; positive pole is connected with power supply both positive and negative polarity, and negative pole powers to whole constant-current circuit.
Voltage reference source circuit is for generation of three road reference voltages, and wherein VCC powers to double operational chip U1, and VREF2 is used for overvoltage crowbar reference voltage, and VREF is used for constant-current circuit reference voltage.
One road reference voltage is used for double operational chip U1 operating voltage; another road reference voltage is used for overvoltage crowbar reference voltage; last road reference voltage is used for constant-current circuit reference voltage; described overvoltage crowbar is used for comparing with reference voltage and exporting low and high level control MOSFET pipe Q1 by detecting input voltage and turn off, and described constant-current circuit is exported low and high level regulate MOSFET pipe Q1 output current for being compared with reference voltage by testing circuit electric current.
Described voltage reference source circuit comprises voltage stabilizing chip U2, the first resistance R1, the second resistance R2, the 3rd resistance R3, the 4th resistance R4, the 5th resistance R5; first resistance R1 one end and diode D1 negative pole are connected to VCC1; K pin and the second resistance R2 of the first resistance R1 other end and voltage stabilizing chip U2 are connected to VCC; the other end of the second resistance R2 and the R pin of voltage stabilizing chip U2 and the 3rd resistance R3 are connected to VREF2, and the 3rd resistance R3 other end and the 4th resistance R4 and the 5th resistance R5 are connected to VREF; 4th resistance R4 and the 5th resistance R5 other end ground connection, the A pin ground connection of voltage stabilizing chip U2.
Described overvoltage crowbar comprises the 8th resistance R8, 9th resistance R9, tenth resistance R10, 4th electric capacity C4, triode Q2, the amplifier modules A part of double operational chip U1 inside, described 9th resistance R9 mono-terminating diode D1 negative pole, the described 9th resistance R9 other end respectively with 3 pin of described double operational chip U1, tenth resistance R10, described 4th electric capacity C4 connects, described tenth resistance R10 other end ground connection, described 4th electric capacity C4 other end ground connection, 2 pin of described double operational chip U1 are connected with the R pin of voltage stabilizing chip U2, described 8th resistance R8 one end is connected with 1 pin of described double operational chip U1, the described 8th resistance R8 other end is connected with the B pin of described triode Q2, the C pin of described triode Q2 is connected with the G pin of MOSFET pipe Q1, the E pin ground connection of described triode Q2.
Described constant-current circuit comprises the 6th resistance R6, 7th resistance R7, 11 resistance R11, second electric capacity C2, MOSFET pipe Q1, the amplifier module B of double operational chip U1 inside, described 7th resistance R7 one end is connected with 6 pin of described double operational chip U1 and described second electric capacity C2 respectively, the described 7th resistance R7 other end respectively with the described second electric capacity C2 other end, described 11 resistance R11, the S pin stating MOSFET pipe Q1 connects, described resistance R11 other end ground connection, 5 pin of described double operational chip U1 respectively with the 3rd resistance R3, 4th resistance R4, 5th resistance R5 connects, described 6th resistance R6 one end is connected with 7 pin of described double operational chip U1, the described 6th resistance R6 other end is connected with the G pin of described MOSFET pipe Q1, the D pin of described MOSFET pipe Q1 is connected with output LED-.
This LED constant current circuit also comprises the first electric capacity C1, described first electric capacity C1 mono-termination power supply positive pole, another termination power supply negative pole of described first electric capacity C1.
This LED constant current circuit also comprises the 5th electric capacity C5, the S pin of MOSFET pipe Q1 described in described 5th electric capacity C5 mono-termination, the D pin of described another termination MOSFET pipe of 5th electric capacity C5 Q1.
This LED constant current circuit also comprises the 3rd electric capacity C3,8 pin of double operational chip U1 described in described 3rd electric capacity C3 mono-termination, described 3rd electric capacity C3 other end ground connection.
The K pin of described voltage stabilizing chip U2 is connected with 8 pin of described double operational chip U1.
In overvoltage crowbar; 9th resistance R9, the tenth resistance R10 sample power input voltage by diode D1; dividing potential drop is also delivered to double operational chip U1 and VREF2 and is compared after the 4th electric capacity C4 filtering; when input voltage makes the 3 pin voltage values of double operational chip U1 be greater than the 2 pin reference voltage V REF2 of double operational chip U1; 1 pin of double operational chip U1 will export high level; triode Q2 conducting; the G pin voltage of the MOSFET pipe Q1 of N ditch drags down and turns off Q1; circuit does not work; play the effect of overvoltage protection, cross cause thermal damage to prevent MOSFET pipe Q1.When input voltage makes the 3 pin voltage values of double operational chip U1 be less than the 2 pin reference voltage V REF2 of double operational chip U1,1 pin of double operational chip U1 is by output low level, triode Q2 ends, present high-impedance state, do not affect the operating state of MOSFET pipe Q1, the operating state of MOSFET pipe Q1 is determined by the 7 pin output levels of double operational chip U1.
In constant-current circuit, 11 resistance R11 is current sampling resistor, in the circuit that its string forms at LED load and Voltage Cortrol MOSFET pipe Q1, its both end voltage is delivered to double operational chip U1 and VREF by the 7th resistance R7 and is compared after the second electric capacity C2 filtering, if when in this circuit, electric current is greater than design load, the voltage at the 11 resistance R11 two ends is higher than VRF, and the 7 pin output levels of double operational chip U1 will decline, thus MOSFET pipe Q1 internal resistance increases, in circuit, electric current reduces; If when in this circuit, electric current is less than design load, the voltage at the 11 resistance R11 two ends is lower than in VRF, and the 7 pin output levels of double operational chip U1 will rise, thus MOSFET pipe Q1 internal resistance reduces, and in circuit, electric current increases.By regulating the resistance of the 4th resistance R4 and the 5th resistance R5, adjusting to the reference voltage VRF of 5 pin of double operational chip U1, playing the effect regulating size of current.During normal work, only and VREF height, and the tenth resistance R11 value is relevant for output current, when LED load increase and reduction time, output current can not produce respective change, realizes output constant current function.
MOSFET: metal-oxide layer semiconductcor field effect transistor, being called for short metal-oxide half field effect transistor (Metal-Oxide-Semiconductor Field-Effect Transistor, MOSFET) is a kind of field-effect transistor that can be widely used in analog circuit and digital circuit.
This voltage stabilizing chip U2 is three end adjustable voltage a reference source chips, electromagnetic interference: Electromagnetic Interference is called for short EMI.
LED constant current circuit of the present utility model has following beneficial effect:
1. efficiency is high: when 24V power voltage supply, peak efficiency can up to 99%;
2. cost is low: this circuit is made up of parts such as control chip, voltage-reference, MOSFET, and circuit is simple, and cost is low;
3. without EMI problem: this circuit because is operated in linear condition, without EMI problem;
4. constant current accuracy is high, and temperature drift is little: this circuit control chip adopts Low Drift Temperature, and the comparator of low DC offset does voltage compare, and in operating voltage and temperature range, constant current accuracy can reach 1%.
Application of the present utility model mainly has more stable 24V voltage to export the illuminator of power supply towards the constant voltage source of (but being not limited to) 24V output voltage, intelligent control system and subway etc.Efficiency is high, and cost is low, and without EMI problem, constant current accuracy is high, Wen Piao little; Shortcoming does not have the voltage range of application of DC-DC circuit wide, but logical is easy to produce the product being applied to various output voltage to LED electrical pressure in product and string and the control of quantity, and to the efficiency to 95%-99%.
And diode-isolated chip power supply in the utility model and power supply input, when low cost, realize connecing anti-protection; N ditch MOSFET pipe series connection regulation and control, complete conducting internal resistance is little, and selection is convenient; Have overvoltage crowbar, fail safe is higher.
Above content is in conjunction with concrete preferred implementation further detailed description of the utility model, can not assert that concrete enforcement of the present utility model is confined to these explanations.For the utility model person of an ordinary skill in the technical field, without departing from the concept of the premise utility, some simple deduction or replace can also be made, all should be considered as belonging to protection range of the present utility model.
Claims (9)
1. a LED constant current circuit, it is characterized in that, comprise voltage reference source circuit, overvoltage crowbar, constant-current circuit, double operational chip (U1), described constant-current circuit comprises MOSFET pipe (Q1), described voltage reference source circuit is for generation of three road reference voltages, one road reference voltage is used for double operational chip (U1) operating voltage, another road reference voltage is used for overvoltage crowbar reference voltage, last road reference voltage is used for constant-current circuit reference voltage, described overvoltage crowbar is used for comparing with reference voltage and exporting low and high level control MOSFET by detecting input voltage and manage (Q1) and turn off, described constant-current circuit is used for being compared with reference voltage by testing circuit electric current exporting low and high level and regulating MOSFET to manage (Q1) output current.
2. LED constant current circuit according to claim 1, it is characterized in that: described voltage reference source circuit comprises voltage stabilizing chip (U2), first resistance (R1), second resistance (R2), 3rd resistance (R3), 4th resistance (R4), 5th resistance (R5), described first resistance (R1) one end is connected to VCC1, K pin and the resistance (R2) of described first resistance (R1) other end and described voltage stabilizing chip (U2) are connected to VCC, R pin and the 3rd resistance (R3) of described second resistance (R2) other end and voltage stabilizing chip (U2) are connected to VREF2, described 3rd resistance (R3) other end and described 4th resistance (R4) and described 5th resistance (R5) are connected to VREF, described 4th resistance (R4) and described 5th resistance (R5) other end ground connection, the A pin ground connection of described voltage stabilizing chip (U2), 5 pin of described double operational chip (U1) are connected with described 3rd resistance (R3), the 4th resistance (R4), the 5th resistance (R5) respectively.
3. LED constant current circuit according to claim 2, it is characterized in that: described overvoltage crowbar comprises the 8th resistance (R8), 9th resistance (R9), tenth resistance (R10), 4th electric capacity (C4), triode (Q2), the amplifier modules A part that double operational chip (U1) is inner, described 9th resistance (R9) respectively with 3 pin of described double operational chip (U1), tenth resistance (R10), described 4th electric capacity (C4) connects, described tenth resistance (R10) other end ground connection, described 4th electric capacity (C4) other end ground connection, 2 pin of described double operational chip (U1) are connected with the R pin of voltage stabilizing chip (U2), described 8th resistance (R8) one end is connected with 1 pin of described double operational chip (U1), described 8th resistance (R8) other end is connected with the B pin of described triode (Q2), the C pin of described triode (Q2) manages (Q1) G pin with MOSFET is connected, the E pin ground connection of described triode (Q2).
4. LED constant current circuit according to claim 1, it is characterized in that: described constant-current circuit comprises the 6th resistance (R6), 7th resistance (R7), 11 resistance (R11), second electric capacity (C2), MOSFET manages (Q1), the amplifier module B that double operational chip (U1) is inner, described 7th resistance (R7) one end is connected with 6 pin of described double operational chip (U1) and described second electric capacity (C2) respectively, described 7th resistance (R7) other end respectively with described second electric capacity (C2) other end, described 11 resistance (R11), the S pin of described MOSFET pipe (Q1) connects, described resistance (R11) other end ground connection, described voltage reference source circuit is connected with 5 pin of described double operational chip (U1), described 6th resistance (R6) one end is connected with 7 pin of described double operational chip (U1), described 6th resistance (R6) other end manages (Q1) G pin with described MOSFET is connected, the D pin of described MOSFET pipe (Q1) is connected with output (LED-).
5. LED constant current circuit according to claim 3, it is characterized in that: this LED constant current circuit also comprises the diode (D1) as anti-reverse protection diode, described diode (D1) positive pole is connected with power supply both positive and negative polarity, described diode (D1) negative pole powers to whole constant-current circuit, described diode (D1) negative pole is connected to VCC1, described 9th resistance (R9) one end is connected with described diode (D1) negative pole, described 9th resistance (R9) other end respectively with 3 pin of described double operational chip (U1), tenth resistance (R10), described 4th electric capacity (C4) connects.
6. LED constant current circuit according to claim 1, it is characterized in that: this LED constant current circuit also comprises the 5th electric capacity (C5), MOSFET described in described 5th electric capacity (C5) one termination manages (Q1) S pin, and described 5th electric capacity (C5) another termination MOSFET manages (Q1) D pin.
7. the LED constant current circuit according to any one of claim 1 to 6, it is characterized in that: this LED constant current circuit also comprises the first electric capacity (C1), described first electric capacity (C1) termination power supply positive pole, another termination power supply negative pole of described first electric capacity (C1).
8. the LED constant current circuit according to any one of claim 1 to 6, it is characterized in that: this LED constant current circuit also comprises the 3rd electric capacity (C3), 8 pin of double operational chip (U1) described in described 3rd electric capacity (C3) one termination, described 3rd electric capacity (C3) other end ground connection.
9. LED constant current circuit according to claim 2, is characterized in that: the K pin of described voltage stabilizing chip (U2) is connected with 8 pin of described double operational chip (U1).
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201420495789.8U CN204046886U (en) | 2014-08-29 | 2014-08-29 | Led constant current circuit |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201420495789.8U CN204046886U (en) | 2014-08-29 | 2014-08-29 | Led constant current circuit |
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| Publication Number | Publication Date |
|---|---|
| CN204046886U true CN204046886U (en) | 2014-12-24 |
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| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN201420495789.8U Expired - Fee Related CN204046886U (en) | 2014-08-29 | 2014-08-29 | Led constant current circuit |
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| Country | Link |
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| CN (1) | CN204046886U (en) |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN104219842A (en) * | 2014-08-29 | 2014-12-17 | 深圳市奋勇光电有限公司 | LED constant-current unit |
| EP3125390A1 (en) * | 2015-07-27 | 2017-02-01 | Nxp B.V. | Overvoltage protection circuit |
-
2014
- 2014-08-29 CN CN201420495789.8U patent/CN204046886U/en not_active Expired - Fee Related
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN104219842A (en) * | 2014-08-29 | 2014-12-17 | 深圳市奋勇光电有限公司 | LED constant-current unit |
| EP3125390A1 (en) * | 2015-07-27 | 2017-02-01 | Nxp B.V. | Overvoltage protection circuit |
| US9979183B2 (en) | 2015-07-27 | 2018-05-22 | Nxp B.V. | Over voltage protection circuit |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| C14 | Grant of patent or utility model | ||
| GR01 | Patent grant | ||
| CF01 | Termination of patent right due to non-payment of annual fee | ||
| CF01 | Termination of patent right due to non-payment of annual fee |
Granted publication date: 20141224 Termination date: 20190829 |