A kind of LED constant-current controller of integrated three kinds of output current specifications
Technical field
The invention belongs to the LED lighting technical field, relate in particular to a kind of LED constant-current controller of integrated multiple electric current output specification.
Background technology
The output of traditional LED constant-current controller product mainly contains 350mA, three kinds of output current specifications of 700mA and 1050mA, and the circuit of three kinds of output current specifications has nothing in common with each other, can't be compatible, be inconvenient to produce and user's use.
Summary of the invention
The invention provides a kind of LED constant-current controller of integrated three kinds of output current specifications, be intended to solve the problem that exists in the background technology, can be with 350mA, three kinds of output current specifications of 700mA and 1050mA are integrated in the product, can select wherein a kind of output current specification arbitrarily by using 2 toggle switchs.Simultaneously, this LED constant-current controller also is applicable to the three-in-one constant-current controller of other current specification, multiple constant current output can also be applicable to the multichannel output products.
The technical solution used in the present invention is:
A kind of LED constant-current controller of integrated three kinds of output current specifications, it is characterized in that: it comprises PWM led driver special chip, this special chip drives external power field effect transistor (MOSFET) with fixed frequency, this frequency is determined by biasing resistor (RF) value that is serially connected between special chip frequency leading foot (F) and the ground, its output current value determines that by the source electrode that is serially connected in external power field effect transistor (MOSFET) and foreign current sample resistance (R11) value between the ground voltage of described foreign current sample resistance (R11) feeds back to the test pin (TEST) of described special chip; The output pin of described special chip (OUT) is connected with the grid of described external power field effect transistor (MOSFET), when the voltage of described test pin (TEST) surpasses the set threshold voltage of the peak current comparator that is positioned at described special chip inside, the driving signal ended of described special chip output pin (OUT), described external power field effect transistor (MOSFET) is turn-offed; Between described external power field effect transistor (MOSFET) and described test pin (TEST), add divider resistance (R12), other two the divider resistance (R13 of access in parallel between described electric resistance partial pressure (R12) and described test pin (TEST), R14), described two divider resistance (R13, R14) respectively with 2 toggle switchs in a switch (ON:1, ON:2) polyphone back ground connection.
The LED constant-current controller of described integrated three kinds of output current specifications, it is characterized in that: described two divider resistance (R13, R14) be connected in series two triode (Q10 respectively, Q11), described triode (Q10, Q11) grounded emitter, base stage are connected with a switch in 2 toggle switchs by resistance R 15, R16 respectively, and described 2 toggle switchs connect the positive pole of stabilized voltage power supply respectively; Between described 2 toggle switchs and described resistance R 15, R16, respectively parallel and insert resistance R 25, R26, described resistance R 25, R26 connect the base stage of triode Q20, Q21 respectively, the grounded emitter of triode Q20, Q21, the LED constant-current controller of integrated three kinds of output current specifications that collector electrode is identical with another road links to each other.
The LED constant-current controller of described integrated three kinds of output current specifications is characterized in that, the resistance of described current sampling resistor (R11) is 0.68W ± 1%; Other two resistance (R13 of access in parallel between the resistance (R12) that adds between described external power field effect transistor (MOSFET) and the described test pin (TEST), described resistance (R12) and the described test pin (TEST), R14) be the paster fixed carbon resister of 1% precision, resistance is 1.0kW ± 1%.
The LED constant-current controller of described integrated three kinds of output current specifications is characterized in that, described stabilized voltage power supply is 5 volts.
The LED constant-current controller of described integrated three kinds of output current specifications is characterized in that, the resistance of described current sampling resistor (R11) is 0.68W.
The LED constant-current controller of described integrated three kinds of output current specifications is characterized in that, the threshold voltage of described peak current comparator is 240mV at inner setting.
Description of drawings
Fig. 1 is single channel constant-current circuit schematic diagram of the present invention;
Fig. 2 is two-way constant-current circuit schematic diagram 1 of the present invention;
Fig. 3 is two-way constant-current circuit schematic diagram 2 of the present invention.
Embodiment
The invention will be further described below in conjunction with accompanying drawing.
In the single channel constant-current circuit as shown in Figure 1, this circuit is core with PWM led driver special chip HV9910B, this chip drives external power field effect transistor (MOSFET) with the fixed frequency up to 300KHz, its frequency determines that by biasing resistor RF value its output current value is determined by foreign current sample resistance R11 value.Its output current value determines that by the source electrode that is serially connected in external power field effect transistor (MOSFET) and foreign current sample resistance (R11) value between the ground voltage of foreign current sample resistance (R11) feeds back to the test pin (TEST) of special chip HV9910B; The output pin of described special chip (OUT) is connected with the grid of described external power field effect transistor (MOSFET), when the voltage of described test pin (TEST) surpasses the set threshold voltage of the peak current comparator that is positioned at described special chip inside, the driving signal ended of described special chip output pin (OUT), described external power field effect transistor (MOSFET) is turn-offed; Between described external power field effect transistor (MOSFET) and described test pin (TEST), add divider resistance (R12), other two the divider resistance (R13 of access in parallel between described electric resistance partial pressure (R12) and described test pin (TEST), R14), described two divider resistance (R13, R14) respectively with 2 toggle switchs in a switch (ON:1, ON:2) polyphone back ground connection.
The resistance of described current sampling resistor (R11) is 0.68W ± 1%; Other two resistance (R13 of access in parallel between the resistance (R12) that adds between described external power field effect transistor (MOSFET) and the described test pin (TEST), described resistance (R12) and the described test pin (TEST), R14) be the paster fixed carbon resister of 1% precision, resistance is 1.0kW ± 1%.When ON:1 and ON:2 disconnected, the current conversion that the R11 sampling resistor is sampled became voltage all to feed back to the TEST pin of special chip, the load current that obtains: I
Load=Vcs/R11=0.24V/0.68 Ω=350mA.When ON:1 conducting ON:2 turn-offed, the current conversion that the R11 sampling resistor is sampled became voltage earlier by feeding back to the TEST pin of special chip after R12 and the R13 dividing potential drop again, and voltage ratio is 2:1, and the load current that obtains is 700mA.As ON:1 and ON:2 all during conducting, the current conversion that the R11 sampling resistor is sampled becomes voltage earlier by feeding back to the TEST pin of special chip after the R12 dividing potential drop in parallel with R13/R14 again, and voltage ratio is 3:1, and the load current that obtains is 1050mA.
Change the value of resistance R 11, can obtain the output current of other specifications, such as R11 being changed into 0.6 Ω, can obtain 400mA, 800mA, three kinds of electric current outputs of 1200mA.
When the needs multiple constant current is exported, add the branch controlled switch circuit on above-mentioned single channel constant-current circuit basis, as Fig. 2, shown in Figure 3.Fig. 2, Fig. 3 constitute a two-way constant current output circuit jointly, and wherein, the SW1 among Fig. 3 and SW2 signal are from toggle switch ON:1 and ON:2 among Fig. 2.This minute, the controlled switch circuit circuit used 2 toggle switchs and 2 groups of transistor circuits to realize disconnection or the closed control of 2 component piezoresistances, concrete method of attachment is: at described two divider resistance (R13, R14) be connected in series two triode (Q10 respectively, Q11), described triode (Q10, Q11) grounded emitter, base stage are connected with a switch in 2 toggle switchs by resistance R 15, R16 respectively, and described 2 toggle switchs connect the positive pole of 5 volts of stabilized voltage power supplys respectively; Between described 2 toggle switchs and described resistance R 15, R16, respectively parallel and insert resistance R 25, R26, described resistance R 25, R26 connect the base stage of triode Q20, Q21 respectively, the grounded emitter of triode Q20, Q21, the LED constant-current controller of integrated three kinds of output current specifications that collector electrode is identical with another road links to each other.
When ON:1 and ON:2 disconnect, Q10, Q11, Q20, Q21 disconnects, and two-way output is all worked by 350mA; When ON:1 conducting ON:2 disconnects, Q11, the Q21 conducting, Q10, Q20 disconnects, and two-way output is all worked by 700mA; As ON:1 and ON:2 all during conducting, Q10, Q11, Q20, the Q21 conducting, two-way output is all worked by 1050mA.
Thus, the LED constant-current controller of these integrated three kinds of output current specifications can realize that three kinds of constant currents output specifications select arbitrarily, and constant current output way can expand to any multichannel, therefore can reduce production costs, and is user-friendly to.