Triode linear constant current circuit with resistor shunting

Abstract

The utility model discloses a triode linear constant current circuit with resistance shunting, comprising a power supply voltage input end which is connected with an output cathode LED-of the circuit after sequentially passing through a base electrode driving resistor, a negative feedback triode and a plurality of constant current units arranged in parallel. Meanwhile, a power supply voltage input end is connected with an output positive electrode LED + of the circuit, a base electrode of the negative feedback triode is connected with any one of the constant current units through the negative feedback resistor, a collector electrode is connected with the base electrode driving resistor, and an emitter electrode is grounded. According to the utility model, the constant current unit is connected in parallel with the constant current triode through the shunt resistor, and current flowing through the constant current unit and the constant current triode passes through the same sampling resistor to generate negative feedback voltage, so that the triode linear constant current circuit unit with the shunt resistor is formed; the use amount of triodes can be reduced under the condition that the power of the driving circuit is equal, and the circuit cost is reduced.

Description

TECHNICAL FIELD

[0001] The utility model relates to a triode linear constant current circuit with resistance shunt. BACKGROUND

[0002] A large number of linear constant current circuits are used as the driving circuit of LED car light in the existing car light circuit design, in order to meet the requirement of driving circuit power, multiple triodes in parallel are usually adopted, as shown in the drawing, and the circuit has the following shortcomings: the number of triodes used is relatively large, resulting in high cost of the circuit, and the dissipation power of the triode is large. Figure 1 INVENTION CONTENTS

[0003] In view of the above problems, the utility model provides a triode linear constant current circuit with resistance shunt, which effectively solves the problems pointed out in the background art.

[0004] The utility model adopts the technical scheme of:

[0005] A triode linear constant current circuit with resistance shunt, comprising a power supply voltage input end, the power supply voltage input end is connected with the output negative pole LED- of the circuit through a base drive resistor, a negative feedback triode and a plurality of parallel constant current units in turn, and the power supply voltage input end is also connected with the output positive pole LED+ of the circuit, the base of the negative feedback triode is connected with any one of the constant current units through a negative feedback resistor, the collector of the negative feedback triode is connected with the base drive resistor, and the emitter of the negative feedback triode is grounded.

[0006] As a preferred, the constant current unit comprises a constant current triode, a base current limiting resistor, a shunt resistor and a sampling resistor, the base of the constant current triode is connected with the collector of the negative feedback triode through the base current limiting resistor, the collector of the constant current triode is connected with the output negative pole LED- of the circuit, the emitter of the constant current triode is connected with the emitter of the negative feedback triode through the sampling resistor, the base of the negative feedback triode is connected with the emitter of any one of the constant current triodes through the negative feedback resistor, and the shunt resistor is connected with the collector and the emitter of the constant current triode.

[0007] The constant current unit of the utility model is connected in parallel with the shunt resistor and the constant current triode, the current flowing through them all passes through the same sampling resistor, a negative feedback voltage for constant current adjustment of the circuit is generated, a triode linear constant current circuit unit with a shunt resistor is constituted, the utility model shares the dissipation power of the constant current triode through shunt of the shunt resistor, the number of triodes can be reduced under the condition of meeting the driving circuit power, and the circuit cost is reduced. BRIEF DESCRIPTION OF DRAWINGS

[0008] ​Figure 1 is a structural schematic diagram of the prior art;

[0009] Figure 2 is a structural schematic diagram of Example 1. DETAILED DESCRIPTION

[0010] It should be noted that the following detailed description is exemplary in nature and is intended to provide further description of the application. Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs.

[0011] It is to be understood that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of example embodiments in accordance with the present application. As used herein, the singular forms "a", "an" and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms "comprises" and / or "comprising," when used in this specification, specify the presence of stated features, steps, operations, elements, and / or components, but do not preclude the presence or addition of one or more other features, steps, operations, elements, components, and / or groups thereof.

[0012] In addition, in the description of the present application, it needs to be understood that the terms "center", "longitudinal", "transverse", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "clockwise", "counterclockwise" and the like indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, and are only for the purpose of facilitating the description of the present application and simplifying the description, and therefore cannot be understood as indicating or implying that the devices or elements referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as limiting the present application.

[0013] In addition, the terms "first", "second", "third", etc. are used only for descriptive purposes and should not be construed as indicating or implying relative importance or an implied indication of the number of technical features indicated. Therefore, the features defined with "first", "second", etc. can explicitly or implicitly include one or more of the features. In the description of the present application, unless otherwise stated, the meaning of "a plurality of" is two or more, unless otherwise explicitly limited.

[0014] In the present application, unless otherwise explicitly specified and limited, the terms "mounting", "connection", "connecting", "fixing" and the like should be understood in a broad sense, for example, it can be fixedly connected, or it can be detachably connected, or it can be integrally connected; it can be mechanically connected, or it can be electrically connected; it can be directly connected, or it can be indirectly connected through an intermediate medium; it can be the communication inside two elements. For those skilled in the art, the specific meaning of the above terms in the present application can be understood according to the specific circumstances.

[0015] In the utility model, unless another definite provision and limitation, first feature is "on" or "under" second feature, can include that first and second features are in direct contact, also can include that first and second features are not in direct contact but contact through other feature between them. Moreover, first feature "on", "above" and "upper surface" of second feature includes that first feature is directly above and obliquely above second feature, or only indicates that horizontal height of first feature is higher than second feature. First feature "under", "below" and "under surface" of second feature includes that first feature is directly below and obliquely below second feature, or only indicates that horizontal height of first feature is less than second feature.

[0016] The utility model is further described in detail below through specific embodiments combined with drawings.

[0017] As Figure 2 The utility model discloses a linear constant current circuit of triode with resistance shunt, including power supply voltage input end 1, power supply voltage input end 1 is connected with the output negative pole LED-5 of circuit through base drive resistance 2, negative feedback triode 3 and two parallelly arranged constant current unit 4 in proper order, and power supply voltage input end 1 is connected with the output positive pole LED+6 of circuit, the base of negative feedback triode 3 is connected with any one constant current unit 4 through negative feedback resistance 7, the collector of negative feedback triode 3 is connected with base drive resistance 2, and the emitter of negative feedback triode 3 is grounded.

[0018] The constant current unit 4 includes constant current triode 41, base current-limiting resistance 42, shunt resistance 43 and sampling resistance 44, the base of constant current triode 41 is connected with the collector of negative feedback triode 3 through base current-limiting resistance 42, the collector of constant current triode 41 is connected with the output negative pole LED-5 of circuit, the emitter of constant current triode 41 is connected with the emitter of negative feedback triode 3 through sampling resistance 44, the base of negative feedback triode 3 is connected with the emitter of any one constant current triode 41 through negative feedback resistance 7, and both ends of shunt resistance 43 are connected with the collector and the emitter of constant current triode 41 respectively.

[0019] Figure 2In the technical scheme, VIN is a power voltage input end (a direct current power supply, generally ≤24V); LED+ is an output positive pole of the circuit, and is connected with an anode of the LED; LED- is an output negative pole of the circuit, and is connected with a cathode of the LED; Q1, R4, R7 and R2 form a driven constant current unit; Q2, R5 and R8 form another driven constant current unit; the two constant current units are in parallel connection; the technical scheme of the utility model is not limited to a single constant current unit and multiple constant current units in parallel connection; R1 is a base driving resistor; R2 and R3 are base limiting resistors of Q1 and Q2 respectively; R4 and R5 are shunt resistors of Q1 and Q2 respectively; R7 and R8 are sampling resistors of Q1 and Q2 respectively; for the convenience of description, the driven constant current unit formed by Q1, R4, R7 and R2 is described in detail.

[0020] VIN provides a driving current for the base of Q1 through R1 and R2, Q1 is turned on, and a current forms a current loop through "LED+" → a load → "LED-" → (Q1+R4) → R7 → GND; the current flowing through Q1 and R4 generates a voltage drop V b at R7, when the voltage reaches the turn-on voltage of Q3, Q3 is turned on, and the voltage V a at point a is pulled down, so that the current flowing through Q1 is reduced; R6, R7 and Q3 form a negative feedback circuit of the constant current unit, the current flowing through Q1 is adjusted, Q1 is equivalent to an adjustable resistor connected in parallel with R4, and because

[0021] V a = V R2 + V Q1be + V b = V R3 + V Q2be + V c , wherein V a is the voltage at point a, V R2 is the voltage across R2, V Q1be is the voltage between the base b and the emitter e of Q1, V b is the voltage at point b, V R3 is the voltage across R3, V Q2be is the voltage between the base b and the emitter e of Q2, and V cFor the voltage of c point, in the case of R2=R3, R7=R8, the current of "Q2, R5, R8, R3 constitute another driven constant current unit" is approximately equal to the current of "Q1, R4, R7, R2 constitute a driven constant current unit", by reasonably adjusting the resistance value of shunt resistor R4 (R5) and sampling resistor R7 (R8), while the circuit meets the constant current drive, since the shunt resistor R4 (R5) shares the dissipation power of the transistor, the dissipation power borne by Q1 (Q2) can be reduced better, so that the amount of transistors can be reduced under the condition of meeting the driving circuit power.

[0022] Finally, it should be noted that the above is only a specific embodiment of the present application. Obviously, the present application is not limited to the above embodiments, but can have many variations. All variations that can be directly derived or inferred from the disclosed content by those of ordinary skill in the art should be considered within the scope of the present application.

Claims

1. A triode linear constant current circuit with a resistance shunt, characterized by, The power supply voltage input end (1) is connected with the output negative pole LED-(5) of the circuit after passing through the base driving resistor (2), the negative feedback triode (3) and a plurality of parallel arranged constant current units (4) in turn, and is connected with the output positive pole LED+(6) of the circuit at the same time, the base of the negative feedback triode (3) is connected with any one of the constant current units (4) through the negative feedback resistor (7), the collector of the negative feedback triode (3) is connected with the base driving resistor (2), and the emitter of the negative feedback triode (3) is grounded.

2. A linear constant current circuit with a resistor shunt for a triode according to claim 1, characterized in that The constant current unit (4) comprises a constant current triode (41), a base current limiting resistor (42), a shunt resistor (43) and a sampling resistor (44), the base of the constant current triode (41) is connected with the collector of the negative feedback triode (3) through the base current limiting resistor (42), the collector of the constant current triode (41) is connected with the output negative pole LED-(5) of the circuit, the emitter of the constant current triode (41) is connected with the emitter of the negative feedback triode (3) through the sampling resistor (44), the base of the negative feedback triode (3) is connected with the emitter of any one of the constant current triodes (41) through the negative feedback resistor (7), and the two ends of the shunt resistor (43) are connected with the collector and the emitter of the constant current triode (41) respectively.

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