CN112312607A - 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
CN112312607A
CN112312607A CN202010967891.3A CN202010967891A CN112312607A CN 112312607 A CN112312607 A CN 112312607A CN 202010967891 A CN202010967891 A CN 202010967891A CN 112312607 A CN112312607 A CN 112312607A
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resistor
pin
control module
constant current
triode
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CN202010967891.3A
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CN112312607B (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

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Abstract

The invention discloses a constant current switching circuit of an LED induction night lamp, wherein a dial switch is in a normal bright gear and a high bright gear, LED loads have the same constant current, and the brightness of a lamp LED1, a lamp LED2, a lamp LED3 and a lamp 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 extremely simple structure and low cost. The transistors Q5 and Q4 are connected in series to form a composite tube, and form logic AND gate control. Therefore, the constant current switching circuit is simple in overall structure and low in 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, people's intellectuality demand to the product is higher and higher, to current lighting device, no longer satisfy and control its bright going out through artificial control switch, but hope that lighting device can be through whether there is the object to move with automatic control device's bright going out in intelligent response scope. The existing lighting device directly controls the LED load lamp to emit light when sensing moving objects, so that the poor light emitting effect is caused and the safety is low.
Therefore, a constant current driving circuit of the induction lamp is provided, after the induction signal is generated, the induction signal does not directly control the illumination module to emit light, but the induction signal is sent to the constant current driving circuit, and the illumination module is controlled to emit light through the constant current driving circuit, so that the working state of the illumination module is stabilized, and the light emitting effect and the safety are improved. However, the existing constant current driving circuit basically adopts a constant current driving chip, and has the disadvantages of complex structure, large 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 of the background technology. The technical scheme adopted by the invention for solving the technical problems is as follows:
constant current switching circuit of LED response night-light, it includes the power, induction circuit control module, load switch control module, constant current negative feedback module, dial switch and LED load, dial switch and power, induction circuit control module, load switch control module and constant current negative feedback module homogeneous phase are connected, induction circuit control module still with the power, load switch control module is connected, load switch control module and constant current negative feedback module, the LED load links to each other, dial switch has the gear of closing, the normal bright gear, low bright gear and high bright gear:
when the dial switch is dialed to a closed gear, the circuit does not form a loop, and the LED load is not bright;
when the dial switch is dialed to a normally-on gear, the sensing 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 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 sensing circuit control module works, the load switch control module controls the low brightness or the off of the LED load according to an output signal of the sensing circuit control module, and the LED load keeps a constant low-brightness current under the action of the constant-current negative feedback module without fluctuation;
when the dial switch is dialed to a high-brightness gear, the induction circuit control module works, the load switch control module controls the high brightness or the off of the LED load according to an output signal of the induction circuit control module, and the LED load keeps a high 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 low bright current limiting resistors R10 and R10A which are connected in parallel, a group of high bright current limiting resistors R9 and R9A which are connected in parallel, one ends of the low bright current limiting resistors R10 and R10A which are connected in parallel are connected with the load switch control module, the base of the triode Q1 and one ends of the high bright current limiting resistors R9 and R9A which are connected in parallel, the collector and the emitter of the triode Q1 are connected with the load switch control module, the dial switch is provided with an input common pin A3, a first input pin A1, a second input pin A2, a third input pin A4, a fourth input pin A5, an output common pin B3, a first output pin B1, a second output pin B2, a third output pin B4 and a fourth output pin B5, the input common pin B3 is connected with a power supply 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, the third input pin B4 is connected with the load switch control module, and the fourth input pin B5 is suspended; the other ends of the parallel high-brightness current-limiting resistors R9 and R9A are connected with a first output pin A1 and a third output pin A4, the other ends of the parallel low-brightness current-limiting resistors R10 and R10A are connected with a second output pin A2, and a fourth output pin A5 is connected with a load switch control module;
when the dial switch is dialed to a closed gear, the input common pin B3 is in a disconnected state, and a circuit does not form a loop;
when the dial switch is dialed to a normally 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 the constant current negative feedback module enables the LED load to keep a high-bright constant current under the action of base clamping voltage of a triode Q1 and high-bright current-limiting resistors R9 and R9A;
when the dial switch is dialed 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 the constant current negative feedback module enables the LED load to keep a low-brightness constant current under the action of base clamping voltage of a triode Q1 and low-brightness current-limiting resistors R10 and R10A;
when the dial switch is dialed to a high-brightness gear, the input common pin B3 of the dial switch is connected with the first input pin B1, the output common pin A3 of the dial switch is connected with the first output pin A1, and the constant current negative feedback module enables the LED load to keep a high-brightness constant current under the action of base clamping voltage of the triode Q1 and high-brightness current-limiting resistors R9 and R9A.
In a preferred embodiment: the load switch control module comprises a triode Q5, a Q4, an MOS tube Q3, a resistor R14, an R13, an R12 and an R15, the base of the triode Q15 is connected with the inductive circuit control module, the collector of the triode Q15 is connected with the base of the triode Q15 and one end of the resistor R15, the emitter of the triode Q15 is grounded, the collector of the triode Q15 is connected with one end of the resistor R15, the gate of the MOS tube Q15 and one end of the resistor R15, the emitter of the triode Q15 is grounded, the drain of the MOS tube Q15 is connected with the LED load, the source of the MOS tube Q15 is connected with one end of a high-brightness current-limiting resistor R15, one end of an R9 15, a low-brightness current-limiting resistor R15, one end of an R10 15 and the base of the triode Q15 in parallel connection, the collector of the triode Q15 is connected with the other end of the resistor R15, the emitter of the triode Q15 is connected with the emitter of the triode Q15, the emitter, The LED loads are all connected, and two ends of the resistor R15 are respectively connected with the base of the triode Q5, the fourth output pin and the third input pin of the dial switch.
In a preferred embodiment: the sensing circuit control module comprises a sensor PIR, capacitors C1, C2, C3, C4, C5, C6, a resistor R1, R2, R3, R4, R5, R7, R8, 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, a2 nd pin of the chip U1, one end of a capacitor C5, one end of a resistor R1, one end of a resistor R2 and one end of a resistor R4, the other end of the resistor R1 is connected with a 8 th pin of the chip U1, one end of the capacitor C4 and the anode of the photodiode Q4, the other end of the capacitor C4 is connected with the cathode of the photodiode Q4 and the other end of the resistor R4 is connected with the ground, the other end of the resistor R4 is connected with the 7 th pin of the chip U4 and one end of the resistor R4, the other end of the capacitor R4 and the other end of the capacitor R4 are connected with the resistor R4, the other end of the resistor R11 is connected with one end of a resistor R6, one end of a capacitor C6, the base of a triode Q5 and one end of a resistor R15, the other end of a capacitor C6 is connected with the other end of a resistor R3, and the other end of the resistor R6 is connected with the 5 th pin of the chip U1;
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 a chip U1, the other end of a resistor R8 is connected with the other end of a resistor R7, the other end of the capacitor C5 and the G end of the sensor PIR, and the sensor PIR is connected with the ground and 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 supply VCC, the anode of the lamp LED2, the anode of the lamp LED3, the anode of the lamp LED4 and an input common pin of a dial switch, the cathode of the lamp LED1 is connected with one end of a resistor R16, the other end of the resistor R16 is connected with the drain electrode of a MOS tube Q3, one end of a resistor R17 is connected with the cathode of the lamp LED2, the other end of the resistor R17 is connected with the drain electrode of the MOS tube Q3, one end of a 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.
Compared with the background technology, the technical scheme has the following advantages:
1. under the combined action of the dial switch and the constant-current negative feedback module, the load switch control module directly controls the LED load to keep normally bright when the dial switch is positioned at a normally bright gear, and the LED load keeps normally bright constant current under the action of the constant-current negative feedback module without fluctuation; when the dial switch is dialed to a low-brightness gear, the sensing circuit control module works, the load switch control module controls the low brightness or the off of the LED load according to an output signal of the sensing circuit control module, and the LED load keeps a constant low-brightness current under the action of the constant-current negative feedback module without fluctuation; when the dial switch is dialed to a high-brightness gear, the induction circuit control module works, the load switch control module controls the high brightness or the off of the LED load according to an output signal of the induction circuit control module, and the LED load keeps a high constant current without fluctuation under the action of the constant current negative feedback module.
That is, when the dial switch is in a normally bright gear or a high bright gear, the constant current negative feedback module can enable the LED load to keep a high bright constant current.
2. The constant current negative feedback module comprises a triode Q1, a group of low bright current-limiting resistors R10 and R10A which are connected in parallel and a group of high bright current-limiting resistors R9 and R9A which are connected in parallel, because the voltage of the base electrode of the triode Q1 is clamped at 0.6V, when the MOS transistor Q3 is in a conducting state, so that an LED load is bright, constant current which can enable the LED load to keep low bright is obtained on the low bright current-limiting resistors R10 and R10A which are connected in parallel, and constant current which can enable the LED load to keep high bright is obtained on the high bright current-limiting resistors R9 and R9A which are connected in parallel, so that the load cannot fluctuate. Compared with the integrated circuit in the prior art, the constant current negative feedback module has extremely simple structure and low cost.
3. The load switch control module comprises triodes Q5 and Q4, an MOS transistor Q3, resistors R14, R13, R12 and R15, the triodes Q5 and Q4 are connected in series to form a composite tube to form logic AND gate control, when the induction circuit control module outputs a high level signal, Q5 is switched on, Q4 is switched off, Q3 is switched on, and then an 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 bright.
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 photodiode Q2, wherein if light is sufficient, the photodiode does not work, the sensor PIR does not work, and no matter how a human body senses, the sensor PIR does not generate sensing signals; when the light is dark or dark, the photodiode Q2 is turned on, the sensor PIR starts to operate, and once a triggering 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 of the transistor Q5 to start the LED load.
Drawings
The invention is further illustrated by the following figures and examples.
Fig. 1 is a schematic block diagram illustrating a constant current switching circuit of an LED-based night light according to a preferred embodiment.
Fig. 2 is a schematic circuit diagram of a constant current switching circuit of an LED-based night light according to a preferred embodiment.
Detailed Description
In the claims, the specification and the drawings of the present invention, unless otherwise expressly limited, the terms "first", "second" or "third", etc. are used for distinguishing between different items and not for describing a particular sequence.
In the claims, the specification and the drawings of the present invention, unless otherwise expressly limited, all directional or positional relationships indicated by the terms "center," "lateral," "longitudinal," "horizontal," "vertical," "top," "bottom," "inner," "outer," "upper," "lower," "front," "rear," "left," "right," "clockwise," "counterclockwise," and the like are based on the directional or positional relationships indicated in the drawings and are used for convenience in describing the present invention and for simplicity in description, but do not indicate or imply that the device or element so indicated must have a particular orientation or be constructed and operated in a particular orientation, and therefore should not be construed as limiting the scope of the present invention.
In the claims, the description and the drawings of the present application, unless otherwise expressly limited, the terms "fixedly connected" and "fixedly connected" should be interpreted broadly, that is, any connection between the two that is not in a relative rotational or translational relationship, that is, non-detachably fixed, integrally connected, and fixedly connected by other devices or elements.
In the claims, the specification and the drawings of the present invention, the terms "including", "having", and variations thereof, are intended to be inclusive and not limiting.
Referring to fig. 1 to 2, a preferred embodiment of the constant current switching circuit of the LED induction night light includes 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 to 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 further connected to the power supply and the load switch control module, the load switch control module is connected to the constant current negative feedback module and the LED load, and the dial switch has a turn-off gear, a normally-on gear, a low-on gear and a high-on gear:
when the dial switch is dialed to a closed gear, the circuit does not form a loop, and the LED load is not bright;
when the dial switch is dialed to a normally-on gear, the sensing 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 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 sensing circuit control module works, the load switch control module controls the low brightness or the off of the LED load according to an output signal of the sensing circuit control module, and the LED load keeps a constant low-brightness current under the action of the constant-current negative feedback module without fluctuation;
when the dial switch is dialed to a high-brightness gear, the induction circuit control module works, the load switch control module controls the high brightness or the off of the LED load according to an output signal of the induction circuit control module, and the LED load keeps a high 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 transistor Q1, a group of low bright current-limiting resistors R10 and R10A connected in parallel, and a group of high bright current-limiting resistors R9 and R9A connected in parallel, one end of each of the low bright current-limiting resistors R10 and R10A connected in parallel is connected to the load switch control module, the base of the transistor Q1, one end of each of the high bright current-limiting resistors R9 and R9A connected in parallel, the collector and the emitter of the transistor Q1 are connected to the load switch control module, the dial switch has an input common pin a3, a first input pin a1, a second input pin a2, a third input pin a4, and a fourth input pin A5, an output common pin B9, a first output pin B1, a second output pin B2, a third output pin B4, and a fourth output pin B5, the input common pin B3 is connected to the power supply VCC, the output common pin a3 is connected to the load switch control module, and the first input pin B1 is connected to the input pin 2, the third input pin B4 is connected with the load switch control module, and the fourth input pin B5 is suspended; the other ends of the parallel high-brightness current-limiting resistors R9 and R9A are connected with a first output pin A1 and a third output pin A4, the other ends of the parallel low-brightness current-limiting resistors R10 and R10A are connected with a second output pin A2, and a fourth output pin A5 is connected with a load switch control module;
when the dial switch is dialed to a closed gear, the input common pin B3 is in a disconnected state, and a circuit does not form a loop;
when the dial switch is dialed to a normally 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 the constant current negative feedback module enables the LED load to keep a high-bright constant current under the action of base clamping voltage of a triode Q1 and high-bright current-limiting resistors R9 and R9A;
when the dial switch is dialed 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 the constant current negative feedback module enables the LED load to keep a low-brightness constant current under the action of base clamping voltage of a triode Q1 and low-brightness current-limiting resistors R10 and R10A;
when the dial switch is dialed to a high-brightness gear, the input common pin B3 of the dial switch is connected with the first input pin B1, the output common pin A3 of the dial switch is connected with the first output pin A1, and the constant current negative feedback module enables the LED load to keep a high-brightness constant current under the action of base clamping voltage of the triode Q1 and high-brightness current-limiting resistors R9 and R9A.
In this embodiment, the load switch control module includes a transistor Q5, a transistor Q4, a MOS transistor Q3, a resistor R14, a resistor R13, a transistor R12, and a resistor R15, wherein a base of the transistor Q15 is connected to the inductive circuit control module, a collector of the transistor Q15 is connected to a base of the transistor Q15 and one end of the resistor R15, an emitter of the transistor Q15 is grounded, a collector of the transistor Q15 is connected to one end of the resistor R15, a gate of the transistor Q15, and one end of the resistor R15, an emitter of the transistor Q15 is connected to ground, a source of the transistor Q15 is connected to the LED load, a drain of the transistor Q15 is connected to one end of the transistor Q15, a high-brightness current-limiting resistor R15, a low brightness current-limiting resistor R15, one end of the transistor R10 15, and a base of the transistor Q15, a collector of the transistor Q15 is connected to the other end of the transistor Q15, an emitter, The LED loads are all connected, and two ends of the resistor R15 are respectively connected with the base of the triode Q5, the fourth output pin A5 of the dial switch and the third input pin B4 of the dial switch.
In this embodiment, the sensing circuit control module includes a sensor PIR, capacitors C1, C2, C3, C4, C5, C6, resistors R1, R2, R3, R4, R5, R7, R8, R11, a chip U1, and a photodiode Q2, a D terminal of the sensor PIR is connected to a first input pin B1 and a second input pin B2 of the dial switch, a2 nd pin of the chip U1, one terminal of the capacitor C5, one terminal of the resistor R5, and one terminal of the resistor R5, the other terminal of the resistor R5 is connected to an 8 th pin of the chip U5, one terminal of the capacitor C5, an anode of the photodiode Q5, the other terminal of the capacitor C5 is connected to a cathode of the photodiode Q5 and connected to ground, the other terminal of the resistor R5 is connected to one terminal of the first pin 7 th pin of the chip U5, the resistor R5, the other terminal of the resistor R5, the other terminal of the capacitor R5, the resistor R5, the other terminal of the capacitor C5, the resistor R5, the other end of the resistor R11 is connected with one end of a resistor R6, one end of a capacitor C6, the base of a triode Q5 and one end of a resistor R15, the other end of a capacitor C6 is connected with the other end of a resistor R3, and the other end of the resistor R6 is connected with the 5 th pin of the chip U1;
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 a chip U1, the other end of a resistor R8 is connected with the other end of a resistor R7, the other end of the capacitor C5 and the G end of the sensor PIR, and the sensor PIR is connected with the ground and 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 a lamp LED1, an LED2, an LED3, an LED4, a resistor R16, an R17, an R18, and an R19, an anode of the lamp LED1 is connected to the power VCC, an anode of the lamp LED2, an anode of the lamp LED3, an anode of the lamp LED4, and an input common pin B3 of the dial switch, a cathode of the lamp LED1 is connected to one end of the resistor R16, another end of the resistor R16 is connected to a source of the MOS transistor Q3, one end of the resistor R17 is connected to a cathode of the lamp LED2, another end of the resistor R18 is connected to a source of the MOS transistor Q3, one end of the resistor R18 is connected to a cathode of the lamp LED3, another end of the resistor R3 is connected to a cathode of the lamp LED3, and another end of the resistor.
The working principle of the switching circuit is as follows:
when the dial switch is in a closed gear, namely, the input common pin B3 and the output common 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 dialed to a normally-on gear, the input common pin B3 is connected with the third input pin B4, and the output common pin A3 is connected with the third output pin A4, at the moment, as the first input pin B1 and the second input pin B2 are both in an off state, no current flows through the induction circuit control module, and the induction circuit control module does not work; a power supply VCC forms a loop after passing through an input common pin B3, a third input pin B4, a resistor R15 and a triode Q5, the triode Q5 is turned on, the triode Q4 is turned off, and an MOS tube Q3 is turned on, so that a lamp LED1, an LED2, an LED3 and an LED4 are lighted, and current flows through four lamp LEDs 1, an LED2, an LED3, an LED4, four resistors R16, an R17, an R18 and an R19 from the power supply VCC and then flows through an MOS tube Q3, a parallel high-brightness current-limiting resistor R9 and an R9A and then is grounded to form a loop; namely, the LED load is connected in series with the parallel high-brightness current-limiting resistors R9 and R9A. The base voltage clamp of the triode Q1 is 0.6V, so that the parallel high-brightness current-limiting resistors R9 and R9A obtain constant current, and further the four lamps LED1, LED2, LED3 and LED4 all have constant current.
When the dial switch is dialed 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 of the transistor Q5 through R15, and the transistor Q5 is controlled solely by the sensing circuit control module:
if the light is sufficient and 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 a sensing signal; when light is dark or dark, the photosensitive diode Q2 is switched on, the sensor PIR starts to work, once a triggering signal of a human body is sensed, the 5 th pin of the chip U1 outputs a high level, the high level is transmitted to the base electrode of the triode Q5, the Q5 is switched on, the Q4 is switched off, the MOS tube Q3 is switched on, and the lamp LED1, the LED2, the LED3 and the LED4 are turned on;
the current flows from a power supply VCC through four lamps LED1, LED2, LED3, LED4, four resistors R16, R17, R18 and R19, then flows through a MOS tube Q3, a low-brightness current-limiting resistor R10 and a low-brightness current-limiting resistor R10A which are connected in parallel and then is grounded to form a loop; that is, the LED load is connected in series with the parallel low-bright current-limiting resistors R10 and R10A. The base voltage clamp of the triode Q1 is at 0.6V, so that the low-brightness current-limiting resistors R10 and R10A which are connected in parallel obtain constant current, and further the four lamps LED1, LED2, LED3 and LED4 all have constant current.
When the dial switch is dialed to a high-brightness gear, the input common pin B3 of the dial switch is connected with the first input pin B1, the output common pin A3 of the dial switch is connected with the first output pin A1, and then current can enter the induction circuit control module through the first 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 of the transistor Q5 through R15, and the transistor Q5 is controlled solely by the sensing circuit control module:
if the light is sufficient and 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 a sensing signal; when light is dark or dark, the photosensitive diode Q2 is switched on, the sensor PIR starts to work, once a triggering signal of a human body is sensed, the 5 th pin of the chip U1 outputs a high level, the high level is transmitted to the base electrode of the triode Q5, the Q5 is switched on, the Q4 is switched off, the MOS tube Q3 is switched on, and the lamp LED1, the LED2, the LED3 and the LED4 are turned on;
the current flows from a power supply VCC through four lamps LED1, LED2, LED3, LED4, four resistors R16, R17, R18 and R19, then flows through a MOS tube Q3, a parallel high-brightness current-limiting resistor R9 and a parallel high-brightness current-limiting resistor R9A and then is grounded to form a loop; namely, the LED load is connected in series with the parallel high-brightness current-limiting resistors R9 and R9A. The base voltage clamp of the triode Q1 is 0.6V, so that the parallel high-brightness current-limiting resistors R9 and R9A obtain constant current, and further the four lamps LED1, LED2, LED3 and LED4 all have constant current.
Therefore, the LED loads have the same constant current when the dial switch is in a normally bright position and a highly bright position, and the brightness of the lamp LED1, the LED2, the LED3 and the LED4 is the same in the two gear positions.
And compared with the integrated circuit adopted in the prior art, the constant current negative feedback module has extremely simple structure and low cost.
The transistors Q5 and Q4 are connected in series to form a composite tube, and form logic AND gate control.
Therefore, the constant current switching circuit is simple in overall structure and low in cost.
The above description is only a preferred embodiment of the present invention, and therefore should not be taken as limiting the scope of the invention, which is defined by the appended claims and their equivalents.

Claims (5)

  1. The constant current switching circuit of LED response night-light, its characterized in that: it includes the power, the induction circuit control module, load switch control module, constant current negative feedback module, dial switch and LED load, dial switch and power, the induction circuit control module, load switch control module and constant current negative feedback module homogeneous phase are connected, induction circuit control module still is connected with the power, load switch control module and constant current negative feedback module, the LED load links to each other, dial switch has the gear of closing, the gear that often brightens, low bright gear and high bright gear:
    when the dial switch is dialed to a closed gear, the circuit does not form a loop, and the LED load is not bright;
    when the dial switch is dialed to a normally-on gear, the sensing 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 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 sensing circuit control module works, the load switch control module controls the low brightness or the off of the LED load according to an output signal of the sensing circuit control module, and the LED load keeps a constant low-brightness current under the action of the constant-current negative feedback module without fluctuation;
    when the dial switch is dialed to a high-brightness gear, the induction circuit control module works, the load switch control module controls the high brightness or the off of the LED load according to an output signal of the induction circuit control module, and the LED load keeps a high constant current without fluctuation under the action of the constant current negative feedback module.
  2. 2. The constant current switching circuit of an LED-induced night light of claim 1, wherein: the constant current negative feedback module comprises a triode Q1, a group of low bright current limiting resistors R10 and R10A which are connected in parallel, a group of high bright current limiting resistors R9 and R9A which are connected in parallel, one ends of the low bright current limiting resistors R10 and R10A which are connected in parallel are connected with the load switch control module, the base of the triode Q1 and one ends of the high bright current limiting resistors R9 and R9A which are connected in parallel, the collector and the emitter of the triode Q1 are connected with the load switch control module, the dial switch is provided with an input common pin A3, a first input pin A1, a second input pin A2, a third input pin A4, a fourth input pin A5, an output common pin B3, a first output pin B1, a second output pin B2, a third output pin B4 and a fourth output pin B5, the input common pin B3 is connected with a power supply 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, the third input pin B4 is connected with the load switch control module, and the fourth input pin B5 is suspended; the other ends of the parallel high-brightness current-limiting resistors R9 and R9A are connected with a first output pin A1 and a third output pin A4, the other ends of the parallel low-brightness current-limiting resistors R10 and R10A are connected with a second output pin A2, and a fourth output pin A5 is connected with a load switch control module;
    when the dial switch is dialed to a closed gear, the input common pin B3 is in a disconnected state, and a circuit does not form a loop;
    when the dial switch is dialed to a normally 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 the constant current negative feedback module enables the LED load to keep a high-bright constant current under the action of base clamping voltage of a triode Q1 and high-bright current-limiting resistors R9 and R9A;
    when the dial switch is dialed 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 the constant current negative feedback module enables the LED load to keep a low-brightness constant current under the action of base clamping voltage of a triode Q1 and low-brightness current-limiting resistors R10 and R10A;
    when the dial switch is dialed to a high-brightness gear, the input common pin B3 of the dial switch is connected with the first input pin B1, the output common pin A3 of the dial switch is connected with the first output pin A1, and the constant current negative feedback module enables the LED load to keep a high-brightness constant current under the action of base clamping voltage of the triode Q1 and high-brightness current-limiting resistors R9 and R9A.
  3. 3. The constant current switching circuit of an LED-induced night light of claim 2, wherein: the load switch control module comprises a triode Q5, a Q4, an MOS tube Q3, a resistor R14, an R13, an R12 and an R15, the base of the triode Q15 is connected with the inductive circuit control module, the collector of the triode Q15 is connected with the base of the triode Q15 and one end of the resistor R15, the emitter of the triode Q15 is grounded, the collector of the triode Q15 is connected with one end of the resistor R15, the grid of the MOS tube Q15 and one end of the resistor R15, the emitter of the triode Q15 is grounded, the source of the MOS tube Q15 is connected with an LED load, the drain of the MOS tube Q15 is connected with one end of a high-brightness current-limiting resistor R15, one end of an R9 15 and a low-brightness current-limiting resistor R15 which are connected in parallel, one end of the R10 15 and the base of the triode Q15, the collector of the triode Q15 is connected with the other end of the resistor R15, the emitter of the triode Q15 is connected with the emitter of the triode Q15, the LED loads are all connected, and two ends of the resistor R15 are respectively connected with the base of the triode Q5, the fourth output pin A5 of the dial switch and the third input pin B4 of the dial switch.
  4. 4. The constant current switching circuit of an LED-induced night light of claim 3, wherein: the sensing circuit control module comprises a sensor PIR, capacitors C1, C2, C3, C4, C5, C6, a resistor R1, R2, R3, R4, R5, R7, R8, 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 2 nd pin of the chip U1, one end of the capacitor C5, one end of the resistor R5, one end of a resistor R5 and one end of a resistor R5, the other end of the resistor R5 is connected with the 8 th pin of the chip U5, one end of the capacitor C5 and the anode of the photodiode Q5, the other end of the capacitor C5 is connected with the cathode of the photodiode Q5 and the ground, the other end of the resistor R5 is connected with the 7 th pin of the chip U5 and one end of the resistor R5, the other end of the resistor R5 and one end of the capacitor R5 are connected with the capacitor C5 and the resistor R5, the other end of the resistor R11 is connected with one end of a resistor R6, one end of a capacitor C6, the base of a triode Q5 and one end of a resistor R15, the other end of a capacitor C6 is connected with the other end of a resistor R3, and the other end of the resistor R6 is connected with the 5 th pin of the chip U1;
    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 a chip U1, the other end of a resistor R8 is connected with the other end of a resistor R7, the other end of the capacitor C5 and the G end of the sensor PIR, and the sensor PIR is connected with the ground and 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 lamp of claim 4, wherein: 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 supply VCC, the anode of the lamp LED2, the anode of the lamp LED3, the anode of the lamp LED4 and an input common pin B3 of the dial switch, the cathode of the lamp LED1 is connected with one end of a resistor R16, the other end of the resistor R16 is connected with the source of a MOS tube Q3, one end of a resistor R17 is connected with the cathode of the lamp LED2, the other end of the resistor R1 is connected with the source of a MOS tube Q3, one end of a resistor R18 is connected with the cathode of the lamp LED3, the other end of the resistor R3 is connected with the source of the MOS tube Q3, and one end.
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