CN214757012U

CN214757012U - Double NPN constant voltage and constant current lamp strip control circuit

Info

Publication number: CN214757012U
Application number: CN202120884307.8U
Authority: CN
Inventors: 刘念白; 李子琼; 唐勇; 田月; 徐艳云
Original assignee: Zhongshan Zhengdu Lighting Technology Co ltd
Current assignee: Zhongshan Zhengdu Lighting Technology Co ltd
Priority date: 2021-04-27
Filing date: 2021-04-27
Publication date: 2021-11-16
Anticipated expiration: 2031-04-27

Abstract

The utility model relates to a lamp area circuit design technical field, concretely relates to two NPN constant voltage constant current lamp area control circuit, it includes a plurality of emitting diode, triode T1, triode T2, resistance R1 and resistance R2, a plurality of emitting diode form the lamp area group after establishing ties, lamp area group one end links to each other with the VDD end, and the lamp area group other end establishes ties with collecting electrode C end; after the base electrode B end of the triode T1 is connected with one end of the resistor R1 in series, the other end of the resistor R1 is connected with the VDD end in parallel; the end E of the emitter of the triode T1 is connected with a resistor R2 in series; the circuit adopts two triodes and two resistors, wherein one triode and one resistor form a divider resistor of the other triode; the constant-current power supply has the advantages of simple circuit structure, low cost, capability of realizing a closed circuit, no voltage reduction, realization of constant voltage and realization of the function of a constant-current power supply.

Description

Double NPN constant voltage and constant current lamp strip control circuit

Technical Field

The utility model relates to a lamp area circuit design technical field, concretely relates to two NPN constant voltage constant current lamp area control circuit.

Background

The LED lamp strip is formed by assembling LEDs on a strip-shaped flexible circuit board or a PCB rigid board, and the product shape is named like a lamp strip. The LED display screen is widely applied to the fields of showcases, door heads, home decoration, outdoor brightening and the like. However, when the conventional low-voltage LED strip is used, the following problems exist: although the traditional low pressure LED lamp area is collectively called as constant voltage lamp area, when in actual use, there is often the pressure drop to make the luminance of each LED lamp pearl have inhomogeneous phenomenon, lead to influencing decorative effect. In addition, the inside constant voltage circuit and the lamp strip circuit in traditional low pressure LED lamp area are complicated, also lead to cost increase, are unfavorable for the sale and the maintenance in later stage.

SUMMERY OF THE UTILITY MODEL

An object of the utility model is to prior art's defect and not enough, provide a two NPN constant voltage constant current lamp area control circuit.

The utility model relates to a double NPN constant voltage constant current lamp belt control circuit, which comprises a plurality of light emitting diodes, a triode T1, a triode T2, a resistor R1 and a resistor R2,

the light emitting diodes are connected in series to form a lamp strip group, one end of the lamp strip group is connected with the VDD end, and the other end of the lamp strip group is connected with the collector C end in series; after the base electrode B end of the triode T1 is connected with one end of the resistor R1 in series, the other end of the resistor R1 is connected with the VDD end in parallel;

the end E of the emitter of the triode T1 is connected with a resistor R2 in series; the end E of an emitter and the end C of a collector of the triode T2 are connected in parallel with two ends of the ends B of the base of the resistor R2 and the triode T1; the base terminal B of the transistor T2 is connected in parallel to the conductor between the emitter terminal E of the transistor T1 and the resistor R2.

Further, the emitter E terminal of the transistor T2 is connected to the VSS terminal.

Furthermore, the transistor T1 and the transistor T2 are both NPN transistors.

Further, the transistor T1 and the resistor R2 form a voltage dividing resistor of the transistor T1.

Further, the transistor T2 and the resistor R1 form a voltage dividing resistor of the transistor T2.

Further, the final end voltage VCC of the lamp strip group is not lower than the total voltage of the series connection of the plurality of light emitting diodes.

After the structure is adopted, the utility model discloses beneficial effect does: the utility model discloses a double NPN constant voltage constant current lamp area control circuit, it adopts two triodes and two resistances, wherein one triode and one resistance constitute the divider resistance of another triode; the constant-current power supply has the advantages of simple circuit structure, low cost, capability of realizing a closed circuit, no voltage reduction, realization of constant voltage and realization of the function of a constant-current power supply.

Drawings

The accompanying drawings, which are included to provide a further understanding of the invention and are incorporated in and constitute a part of this application, do not constitute a limitation of the invention, and in which:

fig. 1 is a schematic diagram of the circuit principle of the present invention.

Detailed Description

In order to make the objects, technical solutions and advantages of the embodiments of the present invention clearer, the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention, and it is obvious that the described embodiments are some, but not all, embodiments of the present invention. Based on the embodiments in the present invention, all other embodiments obtained by a person skilled in the art without creative efforts belong to the protection scope of the present invention.

In the description of the present invention, it should be noted that the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the drawings, and are only for convenience of description and simplification of description, but do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and thus, should not be construed as limiting the present invention.

As shown in fig. 1, the dual NPN constant voltage constant current lamp strip control circuit according to this embodiment includes a plurality of light emitting diodes, a transistor T1, a transistor T2, a resistor R1, and a resistor R2,

Furthermore, the transistor T1 and the transistor T2 are both NPN transistors.

The working principle of the design is as follows:

in this design, a plurality of emitting diode are LED lamp pearl D1 in the circuit, and D2 is all the way to LED lamp pearl Dn. In this design, in the circuit, LED lamp pearl D1, D2 are all connected in series respectively to power and main control triode T1 up to LED lamp pearl Dn and resistance RES2 in the circuit, and establish ties each other. According to the graph shown in fig. 1, the current flowing through the LED lamp bead D is the sum of the base current of the triode T2 and the current flowing through the RES 2; the current flowing through them is equal. Neglecting the base current of the small triode T2, the current flowing through the resistor RES2 is close to the current flowing through the LED lamp bead. In the above circuit connection, the transistors T1 and R2 are voltage dividing resistors at the base of the transistor T2, and the transistor T2 and the resistor R1 are voltage dividing resistors at the base of the transistor T1, so as to form a relatively closed-loop accurate current control circuit.

In the design, when the triodes T1 are firstly conducted after the power is on in the plurality of series-parallel circuits, the LED lamp group is lightened, the current flows through the resistor RES2 and the voltage on the RES2 is increased along with the increase of the Ic of the triode T1, when the divided voltage U =0.7 × T1Ic1=0.7V at RES2, the transistor T2 will turn from off to on, and the base of T1 is pulled down after the transistor T2 is turned on, at which time the transistor T1 is turned off, the equivalent resistance of the transistor T1 becomes large, so that the current flowing through R2 decreases, the voltage on RES2 decreases, the base voltage of transistor T1 is raised again, thus, the current of the LED straight circuit is controlled to be I =0.7/RES2V, the interaction of the two tubes is continued until the circuit is balanced, that is, the current flowing through R2 (approximately equal to D) cannot be large or small, but is a constant value through the resistance RES2, thereby realizing the function of a constant current power supply.

If Ic flowing through the transistor T1 is smaller than the set value after the LED is turned on, the voltage across the resistor RES2 is decreased, when the base potential of the transistor T2 is decreased to below 0.6V, the transistor T2 is turned from on to off, the equivalent resistance of the transistor T2 is correspondingly increased, the transistor T2 is the lower bias resistor of the transistor T1, and its off causes the base voltage of the transistor T1 to rise, so that the on state of the transistor T1 is close to the saturation direction, the equivalent resistance of the transistor T1 is decreased, the equivalent resistance of the transistor T1 is decreased, the current flowing through R2 is increased, and the same is continued until the circuit is balanced, that is, the current flowing through R2 (approximately equal to D) is neither large nor small, but is a constant value set in advance by the resistor RES 2.

In the design, the magnitude of the constant current is determined by the resistance of RES2 and the Vbe of a triode T2, and the output current I = T2Vbe =0.6V/RES2 of the circuit.

In the design, in the circuit, the circuit current passing through the LED lamp beads D1, D2, n, Dn and the triode must be direct current, and the final end voltage VCC of the lamp strip should not be lower than the total voltage of the serially connected lamp beads, otherwise, the LED light source may not enter a constant current state, so that the triode T1 and the triode T2 cannot go into a closed loop state, and the current flowing through the lamp bead D cannot exceed the maximum collector dissipation current ic of the triode T1, that is, the saturation current × the saturation voltage drop is the dissipation power. The maximum voltage cannot exceed the maximum withstand voltage of the tube. The output power of the triode is different along with the output voltage, and the higher the voltage is, the higher the power is. The maximum voltage cannot exceed the maximum withstand voltage of the tube.

The above embodiments are only used to illustrate the technical solution of the present invention, and not to limit it; although the present invention has been described in detail with reference to the foregoing embodiments, it should be understood by those skilled in the art that: the technical solutions described in the foregoing embodiments may still be modified, or some technical features may be equivalently replaced; such modifications and substitutions do not depart from the spirit and scope of the present invention in its corresponding aspects.

Claims

1. The utility model provides a two NPN constant voltage constant current lamp area control circuit which characterized in that: it comprises a plurality of light emitting diodes, a triode T1, a triode T2, a resistor R1 and a resistor R2,

the light emitting diodes are connected in series to form a lamp strip group, one end of the lamp strip group is connected with the VDD end, and the other end of the lamp strip group is connected with the collector C end in series; after the base electrode B end of the triode T1 is connected with one end of the resistor R1 in series, the other end of the resistor R1 is connected with the VDD end in parallel; the end E of the emitter of the triode T1 is connected with a resistor R2 in series; the end E of an emitter and the end C of a collector of the triode T2 are connected in parallel with two ends of the ends B of the base of the resistor R2 and the triode T1; the base terminal B of the transistor T2 is connected in parallel to the conductor between the emitter terminal E of the transistor T1 and the resistor R2.

2. A double NPN constant voltage constant current lamp strip control circuit as claimed in claim 1, wherein: the emitter E terminal of the transistor T2 is connected to the VSS terminal.

3. A double NPN constant voltage constant current lamp strip control circuit as claimed in claim 1, wherein: the triode T1 and the triode T2 are both NPN type triodes.