LED linear constant current circuit with silicon controlled rectifier dimming function and small night lamp lighting function

Abstract

The invention relates to the technical field of LED lighting, and discloses an LED linear constant current circuit with a silicon controlled rectifier dimming function and small night lamp lighting, which comprises a rectification unit, a silicon controlled rectifier dimmer unit, a main lamp lighting unit, a night lamp lighting unit and a night lamp control unit, and is characterized in that the main lamp lighting unit and the night lamp lighting unit are compatible with the silicon controlled rectifier dimming function; wherein the night lamp control unit comprises a control chip U2 of which the model is PM2042; in actual use, compared with an existing constant-current driving circuit with a silicon controlled rectifier dimming function and a night lamp, the constant-current driving circuit has the advantages that the control chip U2 with the model of PM2042 is arranged, and a corresponding peripheral circuit is matched for the control chip U2, so that the lighting control of the night lamp lighting unit is realized, the whole structure is simple, a single chip microcomputer and a power supply chip do not need to be additionally arranged, and the cost is low. The cost is low and the practicability is better.

Description

Technical Field

[0001] The invention relates to the technical field of LED lighting, and in particular to an LED linear constant current circuit with a thyristor dimming function and night light lighting. Background Art

[0002] In some lighting fields, in addition to constant current driving of LED lamps, the product also needs to have a night light function, that is, the product needs to have a backup lamp for lighting.

[0003] The circuit of the existing night light is as follows Figure 1 As shown, the circuit is controlled by a single-chip microcomputer U5, and cooperates with the power supply chip U4 and the optocoupler U2 that provide the working voltage to control the power conversion of the main light and the night light. The working process is as follows:

[0004] First, after the microcontroller U5 is set to be powered on, the PWM signal PWM1 is in a high level state, and the PWM signal PWM2 and the PWM signal PWM3 are in a low level state; the resistor R23, the resistor 24, the capacitor C6, the resistor R22 and the diode D4 form an input voltage detection circuit; when the level from the microcontroller U5 to the diode D4 changes from high to low, the levels of the PWM signal PWM1, the PWM signal PWM2 and the PWM signal PWM3 are reversed once.

[0005] Then, when the AC terminals L and N are connected to the AC voltage, the power supply chip U4 provides a stable voltage to the single-chip computer U5 (PM9802A), the single-chip computer U5 works, the PWM signal PWM1 is high, and the MOS tube Q4 is turned on. The AC voltage passes through the positive electrode of the bridge stack BD1, the diode D1, the main light, the MOS tube Q4, the MOS tube Q1, and the CS resistor connected to Q1 to return to the negative electrode of the bridge stack BD1 to form a loop, and the main light is on;

[0006] In addition, since the PWM signal PWM2 is at a low level, the MOS tube Q3 is turned off, so the night light is not on;

[0007] At the same time, since the PWM signal PWM3 is at a low level, the optocoupler U2 does not work, so the DS of the MOS tube Q2 is saturated and turned on, and the resistors R6 and R7 are connected to the ground through the DS of the MOS tube Q2, so the peak value of the lamp current in the main circuit is

[0008] Then, after the AC voltage connected to the AC terminals L and N is turned off once, the voltage across the diode D4 of the input voltage detection circuit decreases. After the microcontroller U5 detects that the voltage of the diode D4 becomes low, the levels of the PWM signals PWM1, PWM2 and PWM3 are reversed; the PWM signal PWM1 is at a low level, and the MOS tube Q4 is turned off; the PWM signal PWM2 is at a high level, and the MOS tube Q3 is turned on; the PWM signal PWM3 is at a high level, and the optocoupler U2 is turned on, and the MOS tube Q2 is turned off.

[0009] Then, when the AC terminals L and N are connected to the AC voltage again, since the PWM signals PWM2 and PWM3 are high and the PWM signal PWM1 is low, the main light goes out and the night light turns on. The peak current flowing through the night light circuit is The duration of U5 is from the time when the AC voltage connected to the input AC terminals L and N is turned off to the time when it is turned on again. Figure 1 When the time from the AC voltage connected to the input AC terminals L and N to the time from the closure to the reopening exceeds the maintenance level time of the single-chip microcomputer U5, the single-chip microcomputer U5 is reset and restored to the power-on default main light mode.

[0010] for Figure 1 The circuit shown in the figure has the problem of complex circuit when it is actually used, high manufacturing cost and complicated control scheme, which is not conducive to practical application. Summary of the invention

[0011] In view of the shortcomings of the background technology, the present invention provides an LED linear constant current circuit with thyristor dimming function and night light illumination. The technical problem to be solved is that the existing LED linear constant current circuit with night light illumination has the problems of complex structure, high cost and cumbersome control.

[0012] In order to solve the above technical problems, the present invention provides the following technical solutions: an LED linear constant current circuit with thyristor dimming function and night light lighting, comprising a rectifier unit, a thyristor dimmer unit, a main light lighting unit, a night light lighting unit and a night light control unit;

[0013] The rectifier unit is used to rectify the input alternating current; the thyristor dimmer unit is electrically connected to the rectifier unit and the main light lighting unit respectively, and provides a constant driving current for the main light lighting unit based on the DC voltage output by the rectifier unit;

[0014] The input end of the night light lighting unit is electrically connected to the input end of the main light lighting unit;

[0015] The night light control unit includes a control chip U2 of model PM2042, wherein pin No. 1 of the control chip U2 is grounded through capacitor C4, and pin No. 2 of the control chip U2 is grounded through capacitor C3; pin No. 3 of the control chip U2 is electrically connected to one end of resistor R3, one end of capacitor C2 and one end of resistor R5 respectively, the other end of resistor R3 is electrically connected to the positive output end of the rectifier unit, and the other end of resistor R5 and the other end of capacitor C2 are both grounded; pin No. 4 of the control chip U2 is grounded through resistor R4 and electrically connected to pin No. 5 of the control chip U2; pin No. 6 of the control chip U2 is electrically connected to the control end of the regulating switch tube in the thyristor dimmer unit; pin No. 7 of the control chip U2 is electrically connected to the output end of the night light lighting unit and one end of capacitor EC1 respectively, and pin No. 8 of the control chip U2 is electrically connected to the other end of capacitor EC1 and the thyristor dimmer unit respectively, for inputting a second DC voltage, which is less than the DC voltage output by the rectifier unit.

[0016] In a certain embodiment, the rectifier unit includes a rectifier bridge stack of model MB6S.

[0017] In some embodiments, the main light illumination unit includes a plurality of first LED lamps connected in series in sequence, wherein the anode of the first LED lamp at the head end is the input end of the main light illumination unit, and the cathode of the first LED lamp at the end end is the output end of the main light illumination unit.

[0018] In some embodiments, the night light lighting unit includes a plurality of second LED lamps connected in series, wherein the anode of the first second LED lamp is the input end of the night light lighting unit, and the cathode of the last second LED lamp is the output end of the night light lighting unit.

[0019] In a certain embodiment, the thyristor dimmer unit includes a dimmer U3 of model PM2029, a current ripple elimination unit and a voltage detection unit;

[0020] The DC voltage output end of the rectifier unit is electrically connected to the anode of the diode D1, the eighth pin of the dimmer U3, the seventh pin of the dimmer U3 and the voltage detection unit respectively; the first pin of the dimmer U3 is electrically connected to the detection voltage output end of the voltage detection unit and is grounded through the capacitor C5; the second pin of the dimmer U3 is electrically connected to one end of the resistor R6, and the other end of the resistor R6 is electrically connected to one end of the resistor R7, the source of the regulating switch tube Q1 and the third pin of the dimmer U3 respectively, and the other end of the resistor R7 is grounded; the fourth pin of the dimmer U3 is electrically connected to the gate of the regulating switch tube Q1; the fifth pin and the ninth pin of the dimmer U3 are both grounded;

[0021] The cathode of the diode D1 is electrically connected to the input end of the current ripple elimination unit, one end of the capacitor EC2 and pin 8 of the control chip U2 respectively; the output end of the current ripple elimination unit is electrically connected to the input end of the main light lighting unit, and the other end of the capacitor EC2 and the output end of the active lighting unit are electrically connected to the drain of the regulating switch tube Q1.

[0022] In some implementations, the regulating switch tube Q1 is an NMOS tube.

[0023] In a certain embodiment, the voltage detection unit includes a resistor R2 and a resistor R8, one end of the resistor R2 is electrically connected to the DC voltage output end of the rectifier unit, and the other end of the resistor R2 is grounded through the resistor R8, which is the detection voltage output end of the voltage detection unit.

[0024] In a certain embodiment, the current ripple elimination unit includes a chip U3 with model number PM2074D, pin No. 2 of the chip U3 is the input end of the current ripple elimination unit, pin No. 1 of the chip U3 is electrically connected to one end of the capacitor C1, and the other end of the capacitor C1 is electrically connected to pin No. 3 of the chip U3 through the resistor R1, which is the output end of the current ripple elimination unit.

[0025] In some implementations, the capacitor EC2 is an electrolytic capacitor.

[0026] In some implementations, the capacitor EC1 is an electrolytic capacitor.

[0027] Compared with the prior art, the beneficial effect of the present invention is as follows: compared with the existing constant current driving circuit with thyristor dimming function and night light, the present invention realizes the lighting control of the night light lighting unit by setting a control chip U2 with model PM2042 and matching the control chip U2 with corresponding peripheral circuits. The whole structure is simple, no additional single-chip computer and power supply chip are required, the cost is low, and the practicality is better. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 This is the circuit diagram of the existing device with a night light;

[0029] Figure 2 is a circuit diagram of the present invention in an embodiment. DETAILED DESCRIPTION

[0030] The present invention will now be described in further detail with reference to the accompanying drawings. These drawings are simplified schematic diagrams, which only illustrate the basic structure of the present invention in a schematic manner, and therefore only show the components related to the present invention.

[0031] In order to make the LED linear constant current circuit with night light function simple in structure, lower in cost and more practical, Figure 2As shown, this embodiment provides an LED linear constant current circuit with thyristor dimming function and night light lighting, including a rectifier unit 5, a thyristor dimmer unit 1, a main light lighting unit 2, a night light lighting unit 3 and a night light control unit 4;

[0032] The rectifier unit 5 is used to rectify the input AC power; the thyristor dimmer unit 1 is electrically connected to the rectifier unit 5 and the main light lighting unit 2 respectively, and provides a constant driving current for the main light lighting unit 2 based on the DC voltage output by the rectifier unit 5;

[0033] The input end of the night light lighting unit 3 is electrically connected to the input end of the main light lighting unit 2;

[0034] The night light control unit 4 includes a control chip U2 of model PM2042, pin 1 of the control chip U2 is grounded through capacitor C4, and pin 2 of the control chip U2 is grounded through capacitor C3; pin 3 of the control chip U2 is electrically connected to one end of the resistor R3, one end of the capacitor C2 and one end of the resistor R5, respectively, the other end of the resistor R3 is electrically connected to the positive output end of the rectifier unit, and the other end of the resistor R5 and the other end of the capacitor C2 are both grounded; pin 4 of the control chip U2 is grounded through resistor R4 and electrically connected to pin 5 of the control chip U2; pin 6 of the control chip U2 is electrically connected to the control end of the regulating switch tube Q1 in the thyristor dimmer unit 1; pin 7 of the control chip U2 is electrically connected to the output end of the night light lighting unit 3 and one end of the capacitor EC1, and pin 8 of the control chip U2 is electrically connected to the other end of the capacitor EC1 and the thyristor dimmer unit 1, respectively, for inputting a second DC voltage, the second DC voltage is less than the DC voltage output by the rectifier unit 5; wherein capacitor EC1 is an electrolytic capacitor.

[0035] In actual use, compared with the existing constant current driving circuit with thyristor dimming function and night light, the present invention realizes the lighting control of the night light lighting unit by setting a control chip U2 with model PM2042 and matching the control chip U2 with corresponding peripheral circuits. The whole structure is simple, does not require additional single-chip microcomputer and power supply chip, has low cost and better practicality.

[0036] Specifically, in this embodiment, the rectifier unit 5 includes a rectifier bridge stack BR1 of model MB6S. In some implementations, other types of rectifier chips can be selected or other existing rectifier circuits can be set to convert AC voltage into DC voltage, which is not limited here.

[0037] Specifically, in this embodiment, the main light lighting unit 2 includes a plurality of first LED lamps connected in series in sequence, the anode of the first LED lamp at the head end is the input end of the main light lighting unit 2, and the cathode of the first LED lamp at the end end is the output end of the main light lighting unit 2.

[0038] Exemplarily, the main light lighting unit 2 may include two, three, four, five or other number of first LED lamps, which is configured according to actual needs and is not limited here.

[0039] Specifically, in this embodiment, the night light lighting unit 3 includes a plurality of second LED lamps connected in series in sequence, the anode of the second LED lamp at the head end is the input end of the night light lighting unit 3, and the cathode of the second LED lamp at the end end is the output end of the night light lighting unit 3.

[0040] Exemplarily, the night light illumination unit 3 may include two, three, four, five or other number of second LED lamps, which may be configured according to actual needs and is not limited here.

[0041] Specifically, in this embodiment, Figure 2 As shown, the thyristor dimmer unit 1 includes a dimmer U3 of model PM2029, a current ripple elimination unit 10 and a voltage detection unit 11;

[0042] The DC voltage output end of the rectifier unit 5 is electrically connected to the anode of the diode D1, the eighth pin of the dimmer U3, the seventh pin of the dimmer U3 and the voltage detection unit 11 respectively; the first pin of the dimmer U3 is electrically connected to the detection voltage output end of the voltage detection unit 11, and is grounded through the capacitor C5; the second pin of the dimmer U3 is electrically connected to one end of the resistor R6, and the other end of the resistor R6 is electrically connected to one end of the resistor R7, the source of the regulating switch tube Q1 and the third pin of the dimmer U3 respectively, and the other end of the resistor R7 is grounded; the fourth pin of the dimmer U3 is electrically connected to the gate of the regulating switch tube Q1; the fifth pin and the ninth pin of the dimmer U3 are both grounded;

[0043] The cathode of the diode D1 is electrically connected to the input end of the current ripple elimination unit 10, one end of the capacitor EC2 and the eighth pin of the control chip U2 respectively; the output end of the current ripple elimination unit 10 is electrically connected to the input end of the main light lighting unit 2, and the other end of the capacitor EC2 and the output end of the active lighting unit 2 are electrically connected to the drain of the regulating switch tube Q1; wherein the capacitor EC2 is an electrolytic capacitor.

[0044] More specifically, in this embodiment, the regulating switch tube Q1 is an NMOS tube.

[0045] More specifically, in this embodiment, the voltage detection unit 11 includes a resistor R2 and a resistor R8, one end of the resistor R2 is electrically connected to the DC voltage output end of the rectifier unit 5, and the other end of the resistor R2 is grounded through the resistor R8, which is the detection voltage output end of the voltage detection unit 11.

[0046] More specifically, in this embodiment, the current ripple elimination unit 10 includes a chip U3 of model PM2074D, pin No. 2 of the chip U3 is the input end of the current ripple elimination unit, pin No. 1 of the chip U3 is electrically connected to one end of the capacitor C1, and the other end of the capacitor C1 is electrically connected to pin No. 3 of the chip U3 through the resistor R1, which is the output end of the current ripple elimination unit.

[0047] Figure 2 The circuit shown works as follows:

[0048] When an AC voltage is input to the rectifier unit 5, the DC voltage output by the rectifier unit passes through the diode D1 to the No. 8 pin of the control chip U2, and the internal circuit of the control chip U2 charges the capacitor C4 connected to its No. 1 pin. When the level of the No. 1 pin of the control chip U2 reaches the working voltage of the control chip U2, the control chip U2 detects the level of its No. 3 pin; when the level of the No. 3 pin of the control chip U2 is high, the DRN circuit of the No. 7 pin of the control chip U2 is disconnected, the No. 6 pin of the control chip U2 is high impedance, and the main light lighting unit 2 emits light;

[0049] Then, when the AC voltage is removed, the level of the pin 3 of the control chip U2 changes from high to low. When it drops to 1V, the DRN loop of the pin 3 and the pin 7 of the control chip U2 is turned on, and the pin 6 of the control chip U2 becomes low impedance.

[0050] Then when pin 3 of the control chip U2 is powered on again, since pin 6 of the control chip U2 becomes low impedance, the regulating switch tube Q1 is cut off, the main light lighting unit 2 is not lit, the DRN circuit of the control chip U2 is opened, the night light lighting unit 3 is lit, and the peak current flowing through the night light circuit is the reference voltage of the control chip U2 divided by the resistance value of the resistor R4.

[0051] By default, the control chip U2 lights up the main light unit 2 when it is powered on for the first time, that is, the sixth pin of the control chip U2 is high impedance, and the DRN circuit is disconnected; when it is detected that the voltage of the third pin of the control chip U2 changes from high to low and reaches the judgment level, the sixth pin of the control chip U2 and the DRN circuit will flip the state. During the period when the AC voltage is off and then powered on, the power supply of the control chip U2 is maintained by capacitors C4, EC2 and EC1.

[0052] In addition, the second pin of the control chip U2 is a reset pin. When the AC voltage is off, the level of the third pin of the control chip U2 changes from high to low. When it is low to the judgment level, the control chip U2 charges the capacitor C3 with a constant current. When the voltage of the second pin of the control chip U2 rises to the judgment level, the system is reset. At this time, when LN is powered on again, the system still has the main light unit 2 on, and the night light unit 3 off.

[0053] In addition, in this embodiment, since the control chip U2 is an existing chip, the above description of the working process of the control chip U2, that is, how to perform loop control and capacitor charging inside the control chip U2, are all existing technologies and will not be described redundantly here.

[0054] In combination with the above content, it can be known that the structural design of the present invention can make the main light lighting unit 2 and the night light lighting unit 3 compatible with the thyristor dimming function.

[0055] The above is based on the present invention as an inspiration. Through the above description, relevant staff can make various changes and modifications without departing from the technical idea of ​​this invention. The technical scope of this invention is not limited to the content in the specification, and its technical scope must be determined according to the scope of the claims.

Claims

1. LED linear constant current circuit with thyristor dimming function and night light lighting, characterized in that: It includes a rectifier unit, a thyristor dimmer unit, a main light lighting unit, a night light lighting unit and a night light control unit; The rectifier unit is used to rectify the input alternating current; the thyristor dimmer unit is electrically connected to the rectifier unit and the main light lighting unit respectively, and provides a constant driving current for the main light lighting unit based on the DC voltage output by the rectifier unit; The input end of the night light lighting unit is electrically connected to the input end of the main light lighting unit; The night light control unit includes a control chip U2 of model PM2042, wherein pin No. 1 of the control chip U2 is grounded through capacitor C4, and pin No. 2 of the control chip U2 is grounded through capacitor C3; pin No. 3 of the control chip U2 is electrically connected to one end of resistor R3, one end of capacitor C2 and one end of resistor R5 respectively, the other end of resistor R3 is electrically connected to the positive output end of the rectifier unit, and the other end of resistor R5 and the other end of capacitor C2 are both grounded; pin No. 4 of the control chip U2 is grounded through resistor R4 and electrically connected to pin No. 5 of the control chip U2; pin No. 6 of the control chip U2 is electrically connected to the control end of the regulating switch tube in the thyristor dimmer unit; pin No. 7 of the control chip U2 is electrically connected to the output end of the night light lighting unit and one end of capacitor EC1 respectively, and pin No. 8 of the control chip U2 is electrically connected to the other end of capacitor EC1 and the thyristor dimmer unit respectively, for inputting a second DC voltage, which is less than the DC voltage output by the rectifier unit.

2. The LED linear constant current circuit with thyristor dimming function and night light illumination according to claim 1, characterized in that: The rectifier unit includes a rectifier bridge stack of model MB6S.

3. The LED linear constant current circuit with thyristor dimming function and night light illumination according to claim 1, characterized in that: The main light illumination unit comprises a plurality of first LED lamps connected in series in sequence, wherein the anode of the first LED lamp at the head end is the input end of the main light illumination unit, and the cathode of the first LED lamp at the end end is the output end of the main light illumination unit.

4. The LED linear constant current circuit with thyristor dimming function and night light illumination according to claim 1, characterized in that: The night light lighting unit comprises a plurality of second LED lamps connected in series in sequence, wherein the anode of the second LED lamp at the head end is the input end of the night light lighting unit, and the cathode of the second LED lamp at the end end is the output end of the night light lighting unit.

5. The LED linear constant current circuit with thyristor dimming function and night light illumination according to any one of claims 1 to 4, characterized in that: The thyristor dimmer unit includes a PM2029 dimmer U3, a current ripple elimination unit and a voltage detection unit; The DC voltage output end of the rectifier unit is electrically connected to the anode of the diode D1, the eighth pin of the dimmer U3, the seventh pin of the dimmer U3 and the voltage detection unit respectively; the first pin of the dimmer U3 is electrically connected to the detection voltage output end of the voltage detection unit and is grounded through the capacitor C5; the second pin of the dimmer U3 is electrically connected to one end of the resistor R6, and the other end of the resistor R6 is electrically connected to one end of the resistor R7, the source of the regulating switch tube Q1 and the third pin of the dimmer U3 respectively, and the other end of the resistor R7 is grounded; the fourth pin of the dimmer U3 is electrically connected to the gate of the regulating switch tube Q1; the fifth pin and the ninth pin of the dimmer U3 are both grounded; The cathode of the diode D1 is electrically connected to the input end of the current ripple elimination unit, one end of the capacitor EC2 and pin 8 of the control chip U2 respectively; the output end of the current ripple elimination unit is electrically connected to the input end of the main light lighting unit, and the other end of the capacitor EC2 and the output end of the active lighting unit are electrically connected to the drain of the regulating switch tube Q1.

6. The LED linear constant current circuit with thyristor dimming function and night light illumination according to claim 5, characterized in that: The regulating switch tube Q1 is an NMOS tube.

7. The LED linear constant current circuit with thyristor dimming function and night light illumination according to claim 5, characterized in that: The voltage detection unit includes a resistor R2 and a resistor R8. One end of the resistor R2 is electrically connected to the DC voltage output end of the rectifier unit, and the other end of the resistor R2 is grounded through the resistor R8, which is the detection voltage output end of the voltage detection unit.

8. The LED linear constant current circuit with thyristor dimming function and night light illumination according to claim 5, characterized in that: The current ripple elimination unit includes a chip U3 with model number PM2074D, wherein pin No. 2 of the chip U3 is the input end of the current ripple elimination unit, pin No. 1 of the chip U3 is electrically connected to one end of capacitor C1, and the other end of capacitor C1 is electrically connected to pin No. 3 of chip U3 through resistor R1, which is the output end of the current ripple elimination unit.

9. The LED linear constant current circuit with thyristor dimming function and night light illumination according to claim 5, characterized in that: The capacitor EC2 is an electrolytic capacitor.

10. The LED linear constant current circuit with thyristor dimming function and night light illumination according to claim 1, characterized in that: The capacitor EC1 is an electrolytic capacitor.

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