CN203340338U - Over-temperature protection LED drive circuit - Google Patents
Over-temperature protection LED drive circuit Download PDFInfo
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- CN203340338U CN203340338U CN2013201533447U CN201320153344U CN203340338U CN 203340338 U CN203340338 U CN 203340338U CN 2013201533447 U CN2013201533447 U CN 2013201533447U CN 201320153344 U CN201320153344 U CN 201320153344U CN 203340338 U CN203340338 U CN 203340338U
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- current sampling
- sampling resistor
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Abstract
The utility model discloses an over-temperature protection LED drive circuit, and the circuit comprises a main switch tube Q1, a current sampling resistor R1, a current sampling resistor R2, a current sampling resistor R3, a Q2, a biasing resistor R5, and a temperature detection resistor R4RT(NTC). A resistance value of the biasing resistor R5 and a resistance value of the temperature detection resistor R4RT(NTC) are set through external connection, so as to set a temperature range, which is more convenient and more flexible for practical application. Various resistance values of the current sampling resistor R3, the current sampling resistor R1 and the current sampling resistor R2 are set, so as to set a decreasing current ratio of the temperature range. The circuit can meet a whole-range input voltage during the connection of the Q2. A current accuracy of +/-5% during high-low output voltage load can meet the purpose of batch production. During the working of the whole circuit, a whole machine has output all the time no matter whether a current decreases or not. The circuit is simple, convenient to debug, and low in cost.
Description
Technical field
The utility model belongs to electronic applications, relates more specifically to a kind of LED drive circuit.
Background technology
At present, along with the progress of LED technology, the reduction of cost, the LED product enters huge numbers of families step by step, is widely used in various commercial lightings and domestic lighting.LED power supply consumption is more and more, and various requirement is also more and more higher; The protection particularly LED driven is also more and more higher, and existing LED Switching Power Supply by following two kinds of temperature protection, is protected driving often.A kind of is the overheat protector that uses the IC chip internal, protects driving; And the operation principle of this excess temperature protection method is: when the temperature of IC acquires a certain degree, protective device starts to play a role.And the weak point of this method is, general IC can bear very high temperature, and often the IC temperature reaches when 140 degree, 150 are spent and just understands the start-up temperature protective device, can reach the effect of protection driving for this method of power supply of some energy high temperature resistances; Yet a lot of cisco unity malfunctions while driving temperature as IC to reach 140 degree, 150 to spend, possibility on fire even occurs, so this protective device can not extensively apply in the LED driving.Also having a kind of is exactly the serviceability temperature switch protection; By connecting and disconnecting, open or power cutoff, protect driving; That is,, when whole actuation temperature is too high, switch can automatic disconnection.This safeguard measure weak point is: can not guarantee when driving is protected that LED drives the state of lighting in conducting, therefore have the limitation of technology, can not meet the demand on market, can not meet all kinds of clients' actual demand.
The utility model content
The circuit that the utility model provides a kind of overheat protector LED to drive, reach the effect of overheat protector to the control of electric current.In order to realize above purpose and to solve the deficiencies in the prior art part, the utility model is achieved by the following technical programs:
The circuit that a kind of overheat protector LED drives, comprise: main switch Q1, current sampling resistor R1, current sampling resistor R2, current sampling resistor R3, Q2, biasing resistor R5 and temperature detecting resistance R 4RT (NTC), current sampling resistor R1 and current sampling resistor R2 parallel connection, determine the output current of complete machine, current sampling resistor R3 connects and is connected with current sampling resistor R2 with Q2, biasing resistor R5 connects and is connected with Q2 with temperature detecting resistance R 4RT (NTC), current sampling resistor R2, current sampling resistor R3, Q2 forms a loop and is connected with main switch Q1, wherein " NTC " is the English abbreviation of Negative Temperature Coeffcient, the meaning refers to that being exponential relationship with temperature rising resistance reduces, thermistor material with negative temperature coefficient.
Current sampling resistor R1 and current sampling resistor R2 parallel connection, the output current of decision complete machine.
Current sampling resistor R3 connects and is connected with current sampling resistor R2 with Q2.
Biasing resistor R5 connects and is connected with Q2 with temperature detecting resistance R 4RT (NTC).
Current sampling resistor R2, current sampling resistor R3, Q2 form a loop and are connected with main switch Q1.
The utility model beneficial effect compared with prior art is:
(1) the utility model falls the current protection driving by control, can drive and both can reach the purpose that protection LED drives under high temperature at LED, can in to its protection process, make again LED drive in running order.
(2) the utility model is by setting different parameters, and design temperature is protected point easily.
(3) the utility model at high temperature not only plays the effect of protection IC by the mode of falling electric current, whole LED is driven and has also carried out effective protection simultaneously.
(4) the utility model is by setting the different resistances of current sampling resistor R3 and current sampling resistor R1, current sampling resistor R2, in the time of can setting different temperature points easily, falls current ratio.
(5) the utility model circuit can meet the gamut input voltage when the Q2 conducting, and the current precision of high low output voltage load time ± 5% can meet the precision of producing in batches.
(6) during the whole circuit working of the utility model, fall electric current and do not fall electric current, complete machine is that output is arranged fully.Circuit is simple, and debugging is convenient, and cost is low, suitable production.
The accompanying drawing explanation
Fig. 1 is the utility model circuit diagram
Embodiment
In order better to set forth operation principle of the present utility model, below in conjunction with accompanying drawing, the utility model is described in detail:
This circuit comprises as shown in Figure 1: main switch Q1, current sampling resistor R1, current sampling resistor R2, current sampling resistor R3 and decision current sampling resistor R3 connect and the Q2 do not connect, and the biasing resistor R5 of Q2, and temperature detecting resistance R 4RT (NTC).
Biasing resistor R5 and temperature detecting resistance R 4RT (NTC) are in normal temperature work and while not reaching the predetermined point of setting, allow the Vgs of Q2 surpass the Vth of Q2, Q2 will be in conducting state like this, the Q2 conducting, D, it is in parallel with current sampling resistor R1, current sampling resistor R2 to ground that S meets current sampling resistor R3, determines together the output current point of complete machine.
According to current sampling resistor R3 and current sampling resistor R2, the resistance of current sampling resistor R1 is set different value than row, the ratio of the size variation of electric current in the time of the Q2 shutoff can being set easily and opening, and then reach the purpose of setting protection power source, protection product.
Q2 turn-offs: the LED power supply is along with the environment used and the heating of power supply itself, the resistance of temperature detecting resistance R 4RT (NTC) can be more and more less, detecting ambient temperature when higher as temperature detecting resistance R 4RT (NTC) like this, resistance has become very little, thereby impel Q2Vgs to break away from the Vth magnitude of voltage, Q2 enters cut-off region, and Q2 turn-offs, current sampling resistor R3 disconnects, and now the output current of Q1 is just only determined by current sampling resistor R1, current sampling resistor R2.But complete machine still has output, just the power of output has become, and complete machine does not turn-off, and can continue, to the power supply of LED product, to avoid closing bad that electricity causes, reaches the function of real protection power source and product.
Below with reference to specific embodiment of the utility model, the utility model has been described; but those skilled in the art all understand; can carry out various modifications, combination and change to specific embodiment; as relevant components and parts are changed into to series connection by association; or the components and parts of being correlated with change into and in parallel etc. like thatly do not changed the modification of doing under the utility model essence operation principle by series connection, be all to fall in protection category of the present utility model.Should to be considered to be only exemplary to any signals shown in accompanying drawing in addition, rather than restrictive, unless concrete indication separately arranged.When term be also contemplated as make to separate or the ability of combination while not knowing the combination of assembly or step also will be considered to put down in writing.
Claims (1)
1. the circuit that an overheat protector LED drives; it is characterized in that it comprises; switching tube Q1, current sampling resistor R1, current sampling resistor R2, current sampling resistor R3, Q2, biasing resistor R5 and temperature detecting resistance R 4RT; current sampling resistor R1 and current sampling resistor R2 parallel connection; determine the output current of complete machine; current sampling resistor R3 connects and is connected with current sampling resistor R2 with Q2; biasing resistor R5 connects and is connected with Q2 with temperature detecting resistance R 4RT, and current sampling resistor R2, current sampling resistor R3, Q2 form a loop and be connected with main switch Q1.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN2013201533447U CN203340338U (en) | 2013-03-29 | 2013-03-29 | Over-temperature protection LED drive circuit |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN2013201533447U CN203340338U (en) | 2013-03-29 | 2013-03-29 | Over-temperature protection LED drive circuit |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN203340338U true CN203340338U (en) | 2013-12-11 |
Family
ID=49708988
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN2013201533447U Expired - Lifetime CN203340338U (en) | 2013-03-29 | 2013-03-29 | Over-temperature protection LED drive circuit |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN203340338U (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN112492718A (en) * | 2020-12-02 | 2021-03-12 | 上海裕芯电子科技有限公司 | Low-voltage over-temperature current-reducing LED drive circuit |
-
2013
- 2013-03-29 CN CN2013201533447U patent/CN203340338U/en not_active Expired - Lifetime
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN112492718A (en) * | 2020-12-02 | 2021-03-12 | 上海裕芯电子科技有限公司 | Low-voltage over-temperature current-reducing LED drive circuit |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| C14 | Grant of patent or utility model | ||
| GR01 | Patent grant | ||
| CX01 | Expiry of patent term |
Granted publication date: 20131211 |
|
| CX01 | Expiry of patent term |