CN112312607B - Constant current switching circuit of LED induction night lamp - Google Patents

Constant current switching circuit of LED induction night lamp Download PDF

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Publication number
CN112312607B
CN112312607B CN202010967891.3A CN202010967891A CN112312607B CN 112312607 B CN112312607 B CN 112312607B CN 202010967891 A CN202010967891 A CN 202010967891A CN 112312607 B CN112312607 B CN 112312607B
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resistor
pin
brightness
control module
constant current
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CN112312607A (en
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丁张杰
许阳彬
肖根群
吴忠成
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Xiamen Yankon Energetic Lighting Co Ltd
Zhejiang Yankon Group Co Ltd
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Xiamen Yankon Energetic Lighting Co Ltd
Zhejiang Yankon Group Co Ltd
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    • H—ELECTRICITY
    • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05B—ELECTRIC HEATING; ELECTRIC LIGHT SOURCES NOT OTHERWISE PROVIDED FOR; CIRCUIT ARRANGEMENTS FOR ELECTRIC LIGHT SOURCES, IN GENERAL
    • H05B45/00—Circuit arrangements for operating light-emitting diodes [LED]
    • H05B45/10—Controlling the intensity of the light
    • H—ELECTRICITY
    • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05B—ELECTRIC HEATING; ELECTRIC LIGHT SOURCES NOT OTHERWISE PROVIDED FOR; CIRCUIT ARRANGEMENTS FOR ELECTRIC LIGHT SOURCES, IN GENERAL
    • H05B45/00—Circuit arrangements for operating light-emitting diodes [LED]
    • H05B45/30—Driver circuits
    • H05B45/345—Current stabilisation; Maintaining constant current

Abstract

The invention discloses a constant current switching circuit of an LED induction night lamp, wherein a dial switch is in a normal-brightness gear and a high-brightness gear, LED loads have the same constant current, and the brightness of lamps LED1, LED2, LED3 and LED4 is the same in two gear states. And compared with the integrated circuit adopted in the prior art, the constant current negative feedback module has the advantages of extremely simple structure and low cost. The triodes Q5 and Q4 are connected in series to form a composite tube, and logic AND gate control is formed. Therefore, the constant current switching circuit has simple integral structure and low cost.

Description

Constant current switching circuit of LED induction night lamp
Technical Field
The invention relates to a constant current switching circuit of an LED induction night lamp.
Background
Along with the improvement of the living standard of people, the intelligent demand of people on products is higher and higher, and the existing lighting device is not satisfied with the control of the lighting device by an artificial control switch, but hopes that the lighting device can automatically control the lighting device by whether an object moves in an intelligent sensing range. The existing lighting device directly controls the LED load lamp to emit light when sensing a moving object, so that the lighting effect is poor and the primary safety is low.
Therefore, the constant current driving circuit of the induction lamp appears, after the induction signal is generated, the induction signal does not directly control the lighting module to emit light, but sends the induction signal to the constant current driving circuit, and the lighting module is controlled to emit light through the constant current driving circuit so as to stabilize the working state of the lighting module and improve the lighting effect and safety. However, the existing constant current driving circuit basically adopts a constant current driving chip, and has the disadvantages of complex structure, huge volume and high cost.
Disclosure of Invention
The invention provides a constant current switching circuit and a constant current switching method of an LED induction night lamp, which overcome the defects existing in the background technology. The technical scheme adopted for solving the technical problems is as follows:
the constant current switching circuit of the LED induction night lamp comprises a power supply, an induction circuit control module, a load switch control module, a constant current negative feedback module, a dial switch and an LED load, wherein the dial switch is connected with the power supply, the induction circuit control module, the load switch control module and the constant current negative feedback module, the induction circuit control module is also connected with the power supply and the load switch control module, the load switch control module is connected with the constant current negative feedback module and the LED load, and the dial switch is provided with a closing gear, a normal-brightness gear, a low-brightness gear and a high-brightness gear:
when the dial switch is dialed to a closing gear, the circuit does not form a loop, and the LED load is not bright;
when the dial switch is shifted to a normally-on gear, the induction circuit control module does not work, the load switch control module directly controls the LED load to keep normally-on, and the LED load keeps high-on constant current without fluctuation under the action of the constant current negative feedback module;
when the dial switch is dialed to a low-brightness gear, the induction circuit control module works, the load switch control module controls the low brightness or the off of the LED load according to the output signal of the induction circuit control module, and the LED load keeps low-brightness constant current without fluctuation under the action of the constant-current negative feedback module;
when the dial switch is dialed to a high-brightness gear, the sensing circuit control module works, the load switch control module controls the high brightness or the off of the LED load according to the output signal of the sensing circuit control module, and the LED load keeps high-brightness constant current without fluctuation under the action of the constant-current negative feedback module.
In a preferred embodiment: the constant current negative feedback module comprises a triode Q1, a group of parallel low-brightness current limiting resistors R10 and R10A and a group of parallel high-brightness current limiting resistors R9 and R9A, one ends of the parallel low-brightness current limiting resistors R10 and R10A are connected with a load switch control module, a base electrode of the triode Q1 and one ends of the parallel high-brightness current limiting resistors R9 and R9A, a collector electrode and an emitter electrode of the triode Q1 are connected with the load switch control module, the dial switch is provided with an input common pin B3, a first input pin B1, a second input pin B2, a third input pin B4, a fourth input pin B5, an output common pin A3, a first output pin A1, a second output pin A2, a third output pin A4 and a fourth output pin A5, the input common pin B3 is connected with a power VCC, the output common pin A3 is connected with the load switch control module, the first input pin B1 and the second input pin B2 are connected with the sensing circuit control module, and the third input pin B4 is connected with the load switch control module in a suspending mode; the other ends of the high-brightness current-limiting resistors R9 and R9A which are connected in parallel are connected with the first output pin A1 and the third output pin A4, the other ends of the low-brightness current-limiting resistors R10 and R10A which are connected in parallel are connected with the second output pin A2, and the fourth output pin A5 is connected with the load switch control module;
when the dial switch is dialed to a closing gear, the input common pin B3 of the dial switch is in an off state, and the circuit does not form a loop;
when the dial switch is shifted to a normal-brightness gear, an input common pin B3 of the dial switch is connected with a third input pin B4, an output common pin A3 of the dial switch is connected with a third output pin A4, and a constant current negative feedback module keeps a high-brightness constant current through the base clamping voltage of a triode Q1 and the effects of high-brightness current limiting resistors R9 and R9A;
when the dial switch is shifted to a low-brightness gear, an input public pin B3 of the dial switch is connected with a second input pin B2, an output public pin A3 of the dial switch is connected with a second output pin A2, and the constant current negative feedback module keeps low-brightness constant current through base clamping voltage of a triode Q1 and low-brightness current limiting resistors R10 and R10A;
when the dial switch is shifted to a high-brightness gear, the input common pin B3 is connected with the first input pin B1, the output common pin A3 is connected with the first output pin A1, and the constant-current negative feedback module is used for keeping the high-brightness constant current of the LED load under the action of the base clamping voltage of the triode Q1 and the high-brightness current limiting resistors R9 and R9A.
In a preferred embodiment: the load switch control module comprises triodes Q5, Q4, a MOS transistor Q3 and resistors R14, R13, R12 and R15, wherein the base electrode of the triode Q5 is connected with the sensing circuit control module, the collector electrode of the triode Q5 is connected with the base electrode of the triode Q4 and one end of the resistor R12, the emitter electrode of the triode Q5 is grounded, the collector electrode of the triode Q4 is connected with one end of the resistor R13, the grid electrode of the MOS transistor Q3 and one end of the resistor R14, the emitter electrode of the triode Q4 is grounded, the drain electrode of the MOS transistor Q3 is connected with an LED load, the source electrode of the MOS transistor Q3 is connected with one end of a high-brightness current limiting resistor R9 and one end of R9A which are connected in parallel, one end of a low-brightness current limiting resistor R10 and one end of R10A which are connected in parallel, the base electrode of the triode Q1 is connected with the other end of the resistor R14, the emitter electrode of the triode Q1 is connected with the emitter electrode of the triode Q4 and the emitter electrode of the triode Q5, the other end of the resistor R12 is connected with the power supply VCC and the LED load, the two ends of the resistor R13 are connected with the LED load, and the two ends of the resistor Q15 are connected with the output pins of the triode Q5 respectively, and the fourth input pins of a fourth input pin of a high-brightness switch.
In a preferred embodiment: the sensing circuit control module comprises a sensor PIR, a capacitor C1, a C2, a C3, a C4, a C5, a C6, a resistor R1, a resistor R2, a resistor R3, a resistor R4, a resistor R5, a resistor R7, a resistor R8, a resistor R11, a chip U1 and a photodiode Q2, wherein the D end of the sensor PIR is connected with a first input pin and a second input pin of a dial switch, the 2 nd pin of the chip U1, one end of the capacitor C5, one end of the resistor R1, one end of the resistor R2 and one end of the resistor R4 are respectively connected, the other end of the resistor R1 is connected with the first pin of the chip U1, one end of the capacitor C4 and the positive electrode of the photodiode Q2, the other end of the capacitor C4 is connected with the negative electrode of the photodiode Q2 and grounded, the other end of the resistor R2 is connected with the first pin of the chip U1, one end of the resistor R4 is connected with one end of the resistor R5, the first pin of the chip U1, one end of the capacitor C2 is connected with the other end of the resistor R3, the other end of the resistor R5 and the other end of the resistor C2 are respectively connected with one end of the resistor R11 and the other end of the resistor C2, the other end of the resistor R6, one end of the resistor C6 is connected with one end of the resistor C6, one end of the resistor Q6 is connected with the other end of the resistor Q5, and the other end of the resistor Q3 is connected with the other end of the resistor;
the S end of the sensor PIR is connected with one end of a capacitor C3 and one end of a resistor R8, the other end of the capacitor C3 is connected with one end of a resistor R7 and the 3 rd pin of the chip U1, and the other end of the resistor R8 is connected with the other end of the resistor R7, the other end of the capacitor C5 and the G end of the sensor PIR and is grounded and connected with the 2 nd pin of the chip U1; one end of the capacitor C1 is connected with the 1 st pin of the chip U1, and the other end of the capacitor C1 is grounded.
In a preferred embodiment: the LED load comprises a lamp LED1, an LED2, an LED3, an LED4, a resistor R16, an R17, an R18 and an R19, wherein the anode of the lamp LED1 is connected with a power VCC (voltage source), the anode of the lamp LED2, the anode of the lamp LED3, the anode of the lamp LED4 and the input common pin of a dial switch, the cathode of the lamp LED1 is connected with one end of the resistor R16, the other end of the resistor R16 is connected with the drain electrode of the MOS tube Q3, one end of the resistor R17 is connected with the cathode of the lamp LED2, the other end of the resistor R16 is connected with the drain electrode of the MOS tube Q3, one end of the resistor R18 is connected with the cathode of the lamp LED3, the other end of the resistor R19 is connected with the cathode of the lamp LED4, and the other end of the resistor R19 is connected with the drain electrode of the MOS tube Q3.
Compared with the background technology, the technical proposal has the following advantages:
1. through the combined action of the dial switch and the constant current negative feedback module, when the dial switch is positioned in a normally-on gear, the load switch control module directly controls the LED load to keep normally-on, and under the action of the constant current negative feedback module, the LED load keeps normally-on constant current without fluctuation; when the dial switch is dialed to a low-brightness gear, the induction circuit control module works, the load switch control module controls the low brightness or the off of the LED load according to the output signal of the induction circuit control module, and the LED load keeps low-brightness constant current without fluctuation under the action of the constant-current negative feedback module; when the dial switch is dialed to a high-brightness gear, the sensing circuit control module works, the load switch control module controls the high brightness or the off of the LED load according to the output signal of the sensing circuit control module, and the LED load keeps high-brightness constant current without fluctuation under the action of the constant-current negative feedback module.
That is, when the dial switch is in a normal-bright gear or a high-bright gear, the constant-current negative feedback module can enable the LED load to keep high-bright constant current.
2. The constant current negative feedback module comprises a triode Q1, a group of parallel low-brightness current-limiting resistors R10 and R10A and a group of parallel high-brightness current-limiting resistors R9 and R9A, and as the voltage of the base electrode of the triode Q1 is clamped at 0.6V, when the MOS tube Q3 is in a conducting state to enable an LED load to be bright, constant current capable of keeping the LED load to be low-brightness is obtained on the parallel low-brightness current-limiting resistors R10 and R10A, constant current capable of keeping the LED load to be high-brightness is obtained on the parallel high-brightness current-limiting resistors R9 and R9A, and the load cannot fluctuate. Compared with the integrated circuit adopted in the prior art, the constant current negative feedback module has the advantages of extremely simple structure and low cost.
3. The load switch control module comprises triodes Q5 and Q4, MOS (metal oxide semiconductor) transistors Q3, resistors R14, R13, R12 and R15, wherein the triodes Q5 and Q4 are connected in series to form a composite tube to form logic AND gate control, when the sensing circuit control module outputs a high-level signal, the Q5 is conducted, the Q4 is cut off, and the Q3 is conducted, so that the LED load is on; when the sensing circuit control module outputs a low-level signal, Q5, Q4 and Q3 are all cut off, and the LED load is not lightened.
4. The sensing circuit control module comprises a sensor PIR, capacitors C1, C2, C3, C4, C5, C6, resistors R1, R2, R3, R4, R5, R7, R8, R11, a chip U1 and a photosensitive diode Q2, if the light is sufficient, the photosensitive diode does not work, the sensor PIR does not work, and no sensing signal is generated by the sensor PIR no matter how the human body senses; when the light is dark or black, the photosensitive diode Q2 is conducted, the sensor PIR starts to work, once the trigger signal of the human body is sensed, the 5 th pin of the chip U1 outputs a high level, and the high level is transmitted to the base electrode of the triode Q5 so as to start the LED load.
Drawings
The invention is further described below with reference to the drawings and examples.
Fig. 1 is a schematic block diagram of a constant current switching circuit of an LED induction night lamp according to a preferred embodiment.
Fig. 2 is a schematic circuit diagram of a constant current switching circuit of an LED induction night lamp according to a preferred embodiment.
Detailed Description
In the claims, specification and drawings hereof, unless explicitly defined otherwise, the terms "first," "second," or "third," etc. are used for distinguishing between different objects and not for describing a particular sequential order.
In the claims, specification and drawings of the present invention, unless explicitly defined otherwise, references to orientation or positional relationship such as the terms "center", "lateral", "longitudinal", "horizontal", "vertical", "top", "bottom", "inner", "outer", "upper", "lower", "front", "rear", "left", "right", "clockwise", "counterclockwise", etc. are based on the orientation and positional relationship shown in the drawings and are merely for convenience of description and to simplify the description, and do not indicate or imply that the apparatus or element referred to must have a particular orientation or be constructed and operated in a particular orientation, nor should it be construed as limiting the particular scope of the invention.
In the claims, specification and drawings of the present invention, unless explicitly defined otherwise, the terms "fixedly attached" and "fixedly attached" are to be construed broadly as any manner of connection without any positional or rotational relationship between the two, i.e. including non-removable, fixed, integrally connected, and fixedly connected by other means or elements.
In the claims, specification and drawings of the present invention, the terms "comprising," having, "and variations thereof as used herein, are intended to be" including but not limited to.
Referring to fig. 1 to 2, a preferred embodiment of a constant current switching circuit of an LED induction night lamp includes a power source, an induction circuit control module, a load switch control module, a constant current negative feedback module, a dial switch and an LED load, wherein the dial switch is connected with the power source, the induction circuit control module, the load switch control module and the constant current negative feedback module, the induction circuit control module is further connected with the power source and the load switch control module, the load switch control module is connected with the constant current negative feedback module and the LED load, and the dial switch has a closing gear, a normal bright gear, a low bright gear and a high bright gear:
when the dial switch is dialed to a closing gear, the circuit does not form a loop, and the LED load is not bright;
when the dial switch is shifted to a normally-on gear, the induction circuit control module does not work, the load switch control module directly controls the LED load to keep normally-on, and the LED load keeps high-on constant current without fluctuation under the action of the constant current negative feedback module;
when the dial switch is dialed to a low-brightness gear, the induction circuit control module works, the load switch control module controls the low brightness or the off of the LED load according to the output signal of the induction circuit control module, and the LED load keeps low-brightness constant current without fluctuation under the action of the constant-current negative feedback module;
when the dial switch is dialed to a high-brightness gear, the sensing circuit control module works, the load switch control module controls the high brightness or the off of the LED load according to the output signal of the sensing circuit control module, and the LED load keeps high-brightness constant current without fluctuation under the action of the constant-current negative feedback module.
In this embodiment, the constant current negative feedback module includes a triode Q1, a set of parallel low-brightness current limiting resistors R10 and R10A, and a set of parallel high-brightness current limiting resistors R9 and R9A, one ends of the parallel low-brightness current limiting resistors R10 and R10A are connected to a load switch control module, a base electrode of the triode Q1, and one ends of the parallel high-brightness current limiting resistors R9 and R9A, a collector electrode and an emitter electrode of the triode Q1 are connected to the load switch control module, the dial switch has an input common pin B3, a first input pin B1, a second input pin B2, a third input pin B4, a fourth input pin B5, and an output common pin A3, a first output pin A1, a second output pin A2, a third output pin A4, and a fourth output pin A5, the input common pin B3 is connected to the power supply, the output pin A3 is connected to the load switch control module, the first input pin B1 and the second input pin B2 are connected to the sensing circuit control module, and the third input pin B4 is connected to the load switch control module VCC; the other ends of the high-brightness current-limiting resistors R9 and R9A which are connected in parallel are connected with the first output pin A1 and the third output pin A4, the other ends of the low-brightness current-limiting resistors R10 and R10A which are connected in parallel are connected with the second output pin A2, and the fourth output pin A5 is connected with the load switch control module;
when the dial switch is dialed to a closing gear, the input common pin B3 of the dial switch is in an off state, and the circuit does not form a loop;
when the dial switch is shifted to a normal-brightness gear, an input common pin B3 of the dial switch is connected with a third input pin B4, an output common pin A3 of the dial switch is connected with a third output pin A4, and a constant current negative feedback module keeps a high-brightness constant current through the base clamping voltage of a triode Q1 and the effects of high-brightness current limiting resistors R9 and R9A;
when the dial switch is shifted to a low-brightness gear, an input public pin B3 of the dial switch is connected with a second input pin B2, an output public pin A3 of the dial switch is connected with a second output pin A2, and the constant current negative feedback module keeps low-brightness constant current through base clamping voltage of a triode Q1 and low-brightness current limiting resistors R10 and R10A;
when the dial switch is shifted to a high-brightness gear, the input common pin B3 is connected with the first input pin B1, the output common pin A3 is connected with the first output pin A1, and the constant-current negative feedback module is used for keeping the high-brightness constant current of the LED load under the action of the base clamping voltage of the triode Q1 and the high-brightness current limiting resistors R9 and R9A.
In this embodiment, the load switch control module includes a triode Q5, Q4, a MOS transistor Q3, and resistors R14, R13, R12, R15, where the base of the triode Q5 is connected to the sensing circuit control module, the collector of the triode Q5 is connected to the base of the triode Q4, one end of the resistor R12, the emitter of the triode Q5 is grounded, the collector of the triode Q4 is connected to one end of the resistor R13, the gate of the MOS transistor Q3, one end of the resistor R14, the emitter of the triode Q4 is grounded, the source of the MOS transistor Q3 is connected to the LED load, the drain of the MOS transistor Q3 is connected to one end of the high-brightness current-limiting resistor R9, R9A, one end of the low-brightness current-limiting resistor R10, R10A, one end of the base of the triode Q1, the collector of the triode Q1 is connected to the other end of the resistor R14, the emitter of the triode Q1 is connected to the emitter of the triode Q4, the emitter of the triode Q5 is connected to the other end of the resistor R12, the other end of the resistor R13 is connected to the power supply, the LED load is connected to the LED load, the drain of the resistor R15 is connected to the output pins of the triode Q5, and the third input pin of the fourth pin of the input pin of the triode Q5 is connected to the fourth pin, and the fourth pin of the input pin is connected to the fourth pin, respectively.
In this embodiment, the sensing circuit control module includes a sensor PIR, a capacitor C1, C2, C3, C4, C5, C6, a resistor R1, R2, R3, R4, R5, R7, R8, R11, a chip U1, and a photodiode Q2, where a D end of the sensor PIR is connected to a first input pin B1 and a second input pin B2 of the dial switch, a second pin of the chip U1, one end of the capacitor C5, one end of the resistor R1, one end of the resistor R2, and one end of the resistor R4, the other end of the resistor R1 is connected to a first pin of the chip U1, one end of the capacitor C4, an anode of the photodiode Q2, the other end of the resistor C4 is connected to a cathode of the photodiode Q2, the other end of the resistor R2 is connected to one end of the first pin of the chip U1, one end of the resistor R4 is connected to one end of the resistor R5, one end of the first pin of the capacitor C2 is connected to the other end of the chip U3, the other end of the resistor R5 is connected to the other end of the resistor R5, the other end of the resistor C2 is connected to the other end of the resistor C5, and the other end of the resistor C11 is connected to the resistor C6, and the other end of the resistor is connected to the other end of the resistor 3, and the resistor is connected to the other end of the resistor 3;
the S end of the sensor PIR is connected with one end of a capacitor C3 and one end of a resistor R8, the other end of the capacitor C3 is connected with one end of a resistor R7 and the 3 rd pin of the chip U1, and the other end of the resistor R8 is connected with the other end of the resistor R7, the other end of the capacitor C5 and the G end of the sensor PIR and is grounded and connected with the 2 nd pin of the chip U1; one end of the capacitor C1 is connected with the 1 st pin of the chip U1, and the other end of the capacitor C1 is grounded.
In this embodiment, the LED load includes lamp LED1, LED2, LED3, LED4, resistor R16, R17, R18, R19, the positive pole of lamp LED1 links to each other with power VCC, lamp LED2 positive pole, lamp LED3 positive pole, lamp LED4 positive pole, the input common pin B3 of dial switch, the negative pole of lamp LED1 links to each other with resistor R16 one end, the other end of resistor R16 links to each other with the source of MOS tube Q3, one end of resistor R17 links to each other with lamp LED2 negative pole, the other end links to each other with the source of MOS tube Q3, resistor R18 one end links to each other with lamp LED3 negative pole, the other end links to each other with the source of MOS tube Q3, resistor R19 one end links to each other with lamp LED4 negative pole, the other end links to each other with the source of MOS tube Q3.
The working principle of the switching circuit is as follows:
when the dial switch is positioned at a closing gear, namely, the input public pin B3 and the output public pin A3 of the dial switch are in an off state, a circuit does not form a loop, and the whole switching circuit does not work;
when the dial switch is shifted to a normal-bright gear, the input common pin B3 of the dial switch is connected with the third input pin B4, the output common pin A3 of the dial switch is connected with the third output pin A4, and at the moment, as the first input pin B1 and the second input pin B2 are in a disconnected state, no current flows through the sensing circuit control module, and the sensing circuit control module does not work; the power supply VCC forms a loop after being input into a common pin B3, a third input pin B4, a resistor R15 and a triode Q5, the triode Q5 is conducted, the triode Q4 is cut off, the MOS tube Q3 is conducted, the lamps LED1, LED2, LED3 and LED4 are lighted, current flows from the power supply VCC through the four lamps LED1, LED2, LED3, LED4 and the four resistors R16, R17, R18 and R19, and then flows through the MOS tube Q3 and the high-brightness current-limiting resistors R9 and R9A which are connected in parallel and then is grounded to form a loop; namely, the LED load and the high-brightness current-limiting resistors R9 and R9A which are connected in parallel are connected in series. Because the base voltage of the triode Q1 is clamped at 0.6V, the parallel high-brightness current-limiting resistors R9 and R9A obtain constant current, and the four lamps LED1, LED2, LED3 and LED4 have constant current.
When the dial switch is shifted to a low-brightness gear, the input common pin B3 of the dial switch is connected with the second input pin B2, the output common pin A3 of the dial switch is connected with the second output pin A2, and then current can enter the induction circuit control module through the second input pin B2, so that the chip U1 has current, and the chip U1 starts to work; because the fourth output pin A5 is in an off state, current cannot enter the base electrode of the triode Q5 through the R15, and the triode Q5 is controlled by the induction circuit control module only:
if the light is sufficient, the photosensitive diode does not work, the sensor PIR does not work, and no matter how the human body senses, the sensor PIR does not generate sensing signals; when the light is dark or black, the photosensitive diode Q2 is conducted, the sensor PIR starts to work, once a trigger signal of a human body is sensed, the 5 th pin of the chip U1 outputs a high level and transmits the high level to the base electrode of the triode Q5, the Q5 is conducted, the Q4 is cut off, the MOS tube Q3 is conducted, and the lamps LED1, LED2, LED3 and LED4 are lightened;
the current flows from the power supply VCC through the four lamps LED1, LED2, LED3, LED4 and the four resistors R16, R17, R18 and R19, then flows through the MOS tube Q3 and the parallel low-brightness current-limiting resistors R10 and R10A and is grounded to form a loop; that is, the LED load is connected in series with the parallel low-light current limiting resistors R10, R10A. Because the base voltage of the triode Q1 is clamped at 0.6V, the parallel low-brightness current limiting resistors R10 and R10A obtain constant current, and the four lamps LED1, LED2, LED3 and LED4 have constant current.
When the dial switch is dialed to a high-brightness gear, the input common pin B3 is connected with the first input pin B1, the output common pin A3 is connected with the first output pin A1, and then current can enter the induction circuit control module through the first input pin B1, so that the chip U1 has current, and the chip U1 starts to work; because the fourth output pin A5 is in an off state, current cannot enter the base electrode of the triode Q5 through the R15, and the triode Q5 is controlled by the induction circuit control module only:
if the light is sufficient, the photosensitive diode does not work, the sensor PIR does not work, and no matter how the human body senses, the sensor PIR does not generate sensing signals; when the light is dark or black, the photosensitive diode Q2 is conducted, the sensor PIR starts to work, once a trigger signal of a human body is sensed, the 5 th pin of the chip U1 outputs a high level and transmits the high level to the base electrode of the triode Q5, the Q5 is conducted, the Q4 is cut off, the MOS tube Q3 is conducted, and the lamps LED1, LED2, LED3 and LED4 are lightened;
the current flows from the power supply VCC through the four lamps LED1, LED2, LED3, LED4 and the four resistors R16, R17, R18 and R19, then flows through the MOS tube Q3 and the high-brightness current-limiting resistors R9 and R9A which are connected in parallel and then is grounded to form a loop; namely, the LED load and the high-brightness current-limiting resistors R9 and R9A which are connected in parallel are connected in series. Because the base voltage of the triode Q1 is clamped at 0.6V, the parallel high-brightness current-limiting resistors R9 and R9A obtain constant current, and the four lamps LED1, LED2, LED3 and LED4 have constant current.
It can be seen from this that the dial switch is in the normal and high light gear, the LED loads all have the same constant current, and the lamps LED1, LED2, LED3, LED4 have the same brightness in both gear states.
And compared with the integrated circuit adopted in the prior art, the constant current negative feedback module has the advantages of extremely simple structure and low cost.
The triodes Q5 and Q4 are connected in series to form a composite tube, and logic AND gate control is formed.
Therefore, the constant current switching circuit has simple integral structure and low cost.
The foregoing description is only illustrative of the preferred embodiments of the present invention, and therefore should not be taken as limiting the scope of the invention, for all changes and modifications that come within the meaning and range of equivalency of the claims and specification are therefore intended to be embraced therein.

Claims (5)

  1. Constant current switching circuit of LED response night-light, its characterized in that: the LED power supply comprises a power supply, an induction circuit control module, a load switch control module, a constant current negative feedback module, a dial switch and an LED load, wherein the dial switch is connected with the power supply, the induction circuit control module, the load switch control module and the constant current negative feedback module, the induction circuit control module is also connected with the power supply and the load switch control module, the load switch control module is connected with the constant current negative feedback module and the LED load, and the dial switch is provided with a closing gear, a normal-bright gear, a low-bright gear and a high-bright gear:
    when the dial switch is dialed to a closing gear, the circuit does not form a loop, and the LED load is not bright;
    when the dial switch is shifted to a normally-on gear, the induction circuit control module does not work, the load switch control module directly controls the LED load to keep normally-on, and the LED load keeps high-on constant current without fluctuation under the action of the constant current negative feedback module;
    when the dial switch is dialed to a low-brightness gear, the induction circuit control module works, the load switch control module controls the low brightness or the off of the LED load according to the output signal of the induction circuit control module, and the LED load keeps low-brightness constant current without fluctuation under the action of the constant-current negative feedback module;
    when the dial switch is dialed to a high-brightness gear, the sensing circuit control module works, the load switch control module controls the high brightness or the off of the LED load according to the output signal of the sensing circuit control module, and the LED load keeps high-brightness constant current without fluctuation under the action of the constant-current negative feedback module.
  2. 2. The constant current switching circuit of an LED induction night light of claim 1, wherein: the constant current negative feedback module comprises a triode Q1, a group of parallel low-brightness current limiting resistors R10 and R10A and a group of parallel high-brightness current limiting resistors R9 and R9A, one ends of the parallel low-brightness current limiting resistors R10 and R10A are connected with a load switch control module, a base electrode of the triode Q1 and one ends of the parallel high-brightness current limiting resistors R9 and R9A, a collector electrode and an emitter electrode of the triode Q1 are connected with the load switch control module, the dial switch is provided with an input common pin B3, a first input pin B1, a second input pin B2, a third input pin B4, a fourth input pin B5, an output common pin A3, a first output pin A1, a second output pin A2, a third output pin A4 and a fourth output pin A5, the input common pin B3 is connected with a power VCC, the output common pin A3 is connected with the load switch control module, the first input pin B1 and the second input pin B2 are connected with the sensing circuit control module, and the third input pin B4 is connected with the load switch control module in a suspending mode; the other ends of the high-brightness current-limiting resistors R9 and R9A which are connected in parallel are connected with the first output pin A1 and the third output pin A4, the other ends of the low-brightness current-limiting resistors R10 and R10A which are connected in parallel are connected with the second output pin A2, and the fourth output pin A5 is connected with the load switch control module;
    when the dial switch is dialed to a closing gear, the input common pin B3 of the dial switch is in an off state, and the circuit does not form a loop;
    when the dial switch is shifted to a normal-brightness gear, an input common pin B3 of the dial switch is connected with a third input pin B4, an output common pin A3 of the dial switch is connected with a third output pin A4, and a constant current negative feedback module keeps a high-brightness constant current through the base clamping voltage of a triode Q1 and the effects of high-brightness current limiting resistors R9 and R9A;
    when the dial switch is shifted to a low-brightness gear, an input public pin B3 of the dial switch is connected with a second input pin B2, an output public pin A3 of the dial switch is connected with a second output pin A2, and the constant current negative feedback module keeps low-brightness constant current through base clamping voltage of a triode Q1 and low-brightness current limiting resistors R10 and R10A;
    when the dial switch is shifted to a high-brightness gear, the input common pin B3 is connected with the first input pin B1, the output common pin A3 is connected with the first output pin A1, and the constant-current negative feedback module is used for keeping the high-brightness constant current of the LED load under the action of the base clamping voltage of the triode Q1 and the high-brightness current limiting resistors R9 and R9A.
  3. 3. The constant current switching circuit of an LED induction night light of claim 2, wherein: the load switch control module comprises triodes Q5, Q4, a MOS transistor Q3 and resistors R14, R13, R12 and R15, wherein the base electrode of the triode Q5 is connected with the sensing circuit control module, the collector electrode of the triode Q5 is connected with the base electrode of the triode Q4 and one end of the resistor R12, the emitter electrode of the triode Q5 is grounded, the collector electrode of the triode Q4 is connected with one end of the resistor R13, the grid electrode of the MOS transistor Q3 and one end of the resistor R14, the emitter electrode of the triode Q4 is grounded, the source electrode of the MOS transistor Q3 is connected with an LED load, the drain electrode of the MOS transistor Q3 is connected with one end of a high-brightness current limiting resistor R9 and one end of R9A which are connected in parallel, one end of a low-brightness current limiting resistor R10 and one end of R10A which are connected in parallel, the base electrode of the triode Q1 is connected with the other end of the resistor R14, the emitter electrode of the triode Q1 is connected with the emitter electrode of the triode Q4, the emitter electrode of the triode Q5 is grounded, the other end of the resistor R12 is connected with a power supply VCC and the LED load, the two ends of the resistor R13 are connected with the LED load, and the two ends of the resistor Q15 are respectively connected with the drain electrode of the triode Q5 and the output of a fourth pin A and the fourth pin B of a pin of a switch.
  4. 4. The constant current switching circuit of an LED induction night light of claim 3, wherein: the sensing circuit control module comprises a sensor PIR, a capacitor C1, a C2, a C3, a C4, a C5, a C6, a resistor R1, a resistor R2, a resistor R3, a resistor R4, a resistor R5, a resistor R7, a resistor R8, a resistor R11, a chip U1 and a photodiode Q2, wherein the D end of the sensor PIR is connected with a first input pin B1 and a second input pin B2 of a dial switch, the first pin 2 of the chip U1, one end of the capacitor C5, one end of the resistor R1, one end of the resistor R2 and one end of the resistor R4 are connected, the other end of the resistor R1 is connected with the first pin 8 of the chip U1, one end of the capacitor C4, the positive electrode of the photodiode Q2, the other end of the resistor C4 is connected with the negative electrode of the photodiode Q2 and is grounded, the other end of the resistor R2 is connected with the first pin 7 of the chip U1, one end of the resistor R3, the other end of the resistor R4 is connected with one end of the resistor R5, the first pin 6 of the chip U1, one end of the capacitor C2 is connected with one end of the resistor C2, the other end of the resistor R5 and the other end of the resistor R2 is connected with one end of the resistor C11, one end of the resistor C6 is connected with one end of the resistor C6, one end of the other end is connected with the resistor Q6, and the other end is connected with the other end of the resistor;
    the S end of the sensor PIR is connected with one end of a capacitor C3 and one end of a resistor R8, the other end of the capacitor C3 is connected with one end of a resistor R7 and the 3 rd pin of the chip U1, and the other end of the resistor R8 is connected with the other end of the resistor R7, the other end of the capacitor C5 and the G end of the sensor PIR and is grounded and connected with the 2 nd pin of the chip U1; one end of the capacitor C1 is connected with the 1 st pin of the chip U1, and the other end of the capacitor C1 is grounded.
  5. 5. The constant current switching circuit of an LED induction night light of claim 4, wherein: the LED load comprises a lamp LED1, an LED2, an LED3, an LED4, resistors R16, R17, R18 and R19, wherein the anode of the lamp LED1 is connected with a power supply VCC, the anode of the lamp LED2, the anode of the lamp LED3, the anode of the lamp LED4 and an input public pin B3 of a dial switch, the cathode of the lamp LED1 is connected with one end of the resistor R16, the other end of the resistor R16 is connected with the source electrode of the MOS tube Q3, one end of the resistor R17 is connected with the cathode of the lamp LED2, the other end of the resistor R16 is connected with the source electrode of the MOS tube Q3, one end of the resistor R18 is connected with the cathode of the lamp LED3, the other end of the resistor R19 is connected with the cathode of the lamp LED4, and the other end of the resistor R19 is connected with the source electrode of the MOS tube Q3.
CN202010967891.3A 2020-09-15 2020-09-15 Constant current switching circuit of LED induction night lamp Active CN112312607B (en)

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