CN110933811A - LED constant current drive circuit and LED lamp - Google Patents
LED constant current drive circuit and LED lamp Download PDFInfo
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- CN110933811A CN110933811A CN201911368457.7A CN201911368457A CN110933811A CN 110933811 A CN110933811 A CN 110933811A CN 201911368457 A CN201911368457 A CN 201911368457A CN 110933811 A CN110933811 A CN 110933811A
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- temperature coefficient
- coefficient thermistor
- decoder
- mos transistors
- operational amplifier
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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]
- H05B45/30—Driver circuits
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Abstract
The invention discloses an LED constant current driving circuit and an LED lamp, and relates to the field of LED driving. The driving circuit comprises a positive temperature coefficient thermistor, a negative temperature coefficient thermistor, a voltage division circuit, a decoder, an operational amplifier and a first MOS (metal oxide semiconductor) tube. The output end of the decoder is connected with the input end of the voltage division circuit, the output end of the voltage division circuit is connected with the positive phase input end of the operational amplifier, the negative phase input end of the operational amplifier is respectively connected with one end of the positive temperature coefficient thermistor, one end of the negative temperature coefficient thermistor and the source electrode of the first MOS tube, the other end of the positive temperature coefficient thermistor and the other end of the negative temperature coefficient thermistor are both grounded, the output end of the operational amplifier is connected with the grid electrode of the first MOS tube, and the drain electrode of the first MOS tube is connected with the LED lamp. According to the invention, through mutual compensation of the thermistors with positive and negative temperature coefficients and voltage adjustment of the decoder and the voltage division circuit, the constant current flowing through the LED lamp can be ensured, and the illumination performance is improved.
Description
Technical Field
The invention relates to the field of LED driving, in particular to an LED constant current driving circuit and an LED lamp.
Background
The existing LED driver usually includes a transistor and a resistor, and the resistor generates heat, so that the current flowing through the LED is not accurate and is easily affected by voltage. Therefore, the existing driving method is to be improved.
Disclosure of Invention
The present invention is directed to solving at least one of the problems of the prior art. Therefore, the invention provides the LED constant current driving circuit which can ensure that the current flowing through the LED lamp is constant and improve the illumination performance.
The invention further provides the LED lamp.
In a first aspect, an embodiment of the present invention provides an LED constant current driving circuit, including a positive temperature coefficient thermistor, a negative temperature coefficient thermistor, a voltage dividing circuit, a decoder, an operational amplifier, and a first MOS transistor;
the output end of the decoder is connected with the input end of the voltage division circuit, the output end of the voltage division circuit is connected with the positive phase input end of the operational amplifier, the negative phase input end of the operational amplifier is respectively connected with one end of the positive temperature coefficient thermistor, one end of the negative temperature coefficient thermistor and the source electrode of the first MOS tube, the other end of the positive temperature coefficient thermistor and the other end of the negative temperature coefficient thermistor are both grounded, the output end of the operational amplifier is connected with the grid electrode of the first MOS tube, and the drain electrode of the first MOS tube is connected with the LED lamp;
one end of the positive temperature coefficient thermistor and one end of the negative temperature coefficient thermistor are also connected with a plurality of branch circuits, each branch circuit comprises a resistor and a connecting end, and the connecting ends can be grounded or suspended.
The LED constant current driving circuit provided by the embodiment of the invention at least has the following beneficial effects: through mutual compensation of the thermistors with positive and negative temperature coefficients and voltage adjustment of the decoder and the voltage division circuit, the constant current flowing through the LED lamp can be ensured, and the illumination performance is improved.
According to the LED constant current driving circuit according to other embodiments of the present invention, the voltage dividing circuit includes a plurality of MOS transistors, gates of the MOS transistors are correspondingly connected to an output terminal of the decoder, sources of the MOS transistors are connected to a non-inverting input terminal of the operational amplifier, and drains of the MOS transistors are grounded.
According to the LED constant current driving circuit according to other embodiments of the present invention, the voltage dividing circuit includes a plurality of MOS transistors, gates of the MOS transistors are correspondingly connected to the output terminal of the decoder, drains of the MOS transistors are connected to the non-inverting input terminal of the operational amplifier, and sources of the MOS transistors are grounded.
According to the LED constant current driving circuit of other embodiments of the present invention, the thermal characteristics of the positive temperature coefficient thermistor and the negative temperature coefficient thermistor are opposite, so that temperature changes can be compensated for each other.
According to the LED constant current driving circuit according to other embodiments of the present invention, the decoder is a 3-8 decoder, and correspondingly, the voltage dividing circuit includes 8 MOS transistors, and 8 output terminals of the 3-8 decoder are respectively connected to gates of the 8 MOS transistors.
In a second aspect, an embodiment of the invention provides an LED lamp including the LED constant current driving circuit.
Drawings
Fig. 1 is a schematic circuit diagram of an embodiment of an LED constant current driving circuit according to an embodiment of the present invention;
FIG. 2 is a circuit schematic of one embodiment of a 3-8 decoder according to the present invention;
fig. 3 is a schematic circuit diagram of a voltage divider circuit according to an embodiment of the present invention.
Detailed Description
The concept and technical effects of the present invention will be clearly and completely described below in conjunction with the embodiments to fully understand the objects, features and effects of the present invention. It is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all embodiments, and those skilled in the art can obtain other embodiments without inventive effort based on the embodiments of the present invention, and all embodiments are within the protection scope of the present invention.
In the description of the present invention, if an orientation description is referred to, for example, the orientations or positional relationships indicated by "upper", "lower", "front", "rear", "left", "right", etc. are based on the orientations or positional relationships shown in the drawings, only for convenience of describing the present invention and simplifying the description, but not for indicating or implying that the referred device or element must have a specific orientation, be constructed and operated in a specific orientation, and thus should not be construed as limiting the present invention. If a feature is referred to as being "disposed," "secured," "connected," or "mounted" to another feature, it can be directly disposed, secured, or connected to the other feature or indirectly disposed, secured, connected, or mounted to the other feature.
In the description of the embodiments of the present invention, if "a number" is referred to, it means one or more, if "a plurality" is referred to, it means two or more, if "greater than", "less than" or "more than" is referred to, it is understood that the number is not included, and if "greater than", "lower" or "inner" is referred to, it is understood that the number is included. If reference is made to "first" or "second", this should be understood to distinguish between features and not to indicate or imply relative importance or to implicitly indicate the number of indicated features or to implicitly indicate the precedence of the indicated features.
Example one
Referring to fig. 1 to 3, circuit schematic diagrams of the LED constant current driving circuit in the present embodiment are shown. The driving circuit comprises a positive temperature coefficient thermistor R1, a negative temperature coefficient thermistor R2, a voltage division circuit, a decoder, an operational amplifier OP and a first MOS transistor M0.
The output end of the decoder is connected with the input end of the voltage division circuit, the output end of the voltage division circuit is connected with the positive phase input end of the operational amplifier OP, the negative phase input end of the operational amplifier OP is respectively connected with one end of the positive temperature coefficient thermistor R1, one end of the negative temperature coefficient thermistor R2 and the source electrode of the first MOS tube M0, the other end of the positive temperature coefficient thermistor R1 and the other end of the negative temperature coefficient thermistor R2 are grounded, the output end of the operational amplifier OP is connected with the grid electrode of the first MOS tube M0, and the drain electrode of the first MOS tube M0 is connected with the LED lamp.
One end of the positive temperature coefficient thermistor R1 and one end of the negative temperature coefficient thermistor R2 are also connected with a plurality of branches, each branch comprises a resistor and a connecting end, and the connecting ends can be grounded or suspended.
In this embodiment, the decoder is a 3-8 decoder, as shown in FIG. 2. As shown in fig. 3, the voltage divider circuit includes a plurality of MOS transistors M1 to M8, and resistors RA, RB1 to RB7, and resistor RC. Gates T1 to T8 of the MOS transistors M1 to M8 are correspondingly connected to 8 output terminals Y1 to Y8 of the 3-8 decoder, sources of the MOS transistors M1 to M8 are connected to a non-inverting input terminal of the operational amplifier OP, and drains of the MOS transistors M1 to M8 are grounded through resistors RA, RB1 to RB7 and RC, respectively.
It should be noted here that the voltage dividing circuit may also be: drains of the MOS transistors M1 to M8 are connected to a non-inverting input terminal of the operational amplifier OP, and sources of the MOS transistors M1 to M8 are grounded through resistors RA, RB1 to RB7 and RC, respectively.
In addition, other decoders such as 4-16 decoders can be adopted for the decoders, correspondingly, 17 resistors and 16 MOS transistors are needed for the voltage dividing circuit, and 16 output ends of the 4-16 decoders are correspondingly linked with gates of the 16 MOS transistors.
In this embodiment, the 3 inputs of the 3-8 decoder are a1, a2, and A3, respectively. The 3 inputs may input signals by blowing the wires connected thereto. For example, the trimming algorithm is
Wherein, Iout1 is a current flowing through the LED lamp and the chip when no trimming is performed, Iout is a target current value that needs to be trimmed, if Iout1 is 11mA, an Iout increment Δ Iout is 10%, a current needs to be trimmed downwards at this time, and a trimming logic corresponding to Δ Iout being 10% is 010, then 010 is respectively input to 3 input terminals a1, a2, and A3 of the 3-8 decoder (that is, Δ Iout has a mapping relationship with the trimming logic).
In this embodiment, the resistor RA is connected to a voltage VREF, and the voltage value of VREF is 1.2V.
The operation of the above-mentioned driving circuit is described with reference to fig. 1 to 3:
input ends A1, A2 and A3 of the 3-8 decoder can input signals by fusing conducting wires connected with the input ends, 8 output signals Y1-Y8 are respectively input to gates T1-T8 of MOS transistors M1-M8 in a voltage division circuit, MOS transistors M1-M8 are conducted, the output of the voltage division circuit is VF, the VF is connected to a positive input end of an operational amplifier OP and is input to a gate of a first MOS transistor M0 after being amplified. The negative phase input end of the operational amplifier OP is connected to one end of the positive temperature coefficient thermistor R1 and one end of the negative temperature coefficient thermistor R2. The other end of the positive temperature coefficient thermistor R1 and the other end of the negative temperature coefficient thermistor R2 are grounded.
One end of the positive temperature coefficient thermistor R1 and one end of the negative temperature coefficient thermistor R2 are also connected with 5 branches A, B, C, D and E. The branch circuit A comprises a resistor R3 and a connecting end JA, the branch circuit B comprises a resistor R4 and a connecting end JB, the branch circuit C comprises a resistor R5 and a connecting end JC, the branch circuit D comprises a resistor R6 and a connecting end JD, and the branch circuit E comprises a resistor R7 and a connecting end JE. The connection terminals JA-JE can be grounded or suspended, and are determined according to the magnitude of the current flowing through the LED. For example, the current of branch a is 10mA, the current of branch B is 10mA, the current of branch C is 20mA, the current of branch D is 20mA, and the current of branch E is 5 mA. If the current required to flow through the LED is 30mA, the connecting end JA of the branch circuit A and the connecting end JC of the branch circuit C are grounded, the branch circuit A and the branch circuit C are conducted, and the connecting ends of other branch circuits are suspended. Since the drain and source currents of the first MOS transistor are equal, the current flowing through the LED is the sum of the current of the branch a and the current of the branch C, i.e. 30 mA.
In this embodiment, on the one hand, the thermal characteristics of the positive temperature coefficient thermistor R1 and the negative temperature coefficient thermistor R2 are opposite, so that temperature changes can be compensated for each other. Since the formula of the current I flowing through the LED is I/R, and the positive temperature coefficient thermistor R1 and the negative temperature coefficient thermistor R2 which are mutually compensated are adopted, R in the formula does not change. On the other hand, the voltage U can be kept constant by the adjustment of the 3-8 decoder and the voltage divider circuit. Therefore, the drive circuit can ensure that the current I flowing through the LED is constant, thereby achieving the purpose of constant current drive and improving the illumination performance.
Example two
The embodiment provides an LED lamp which comprises the LED constant current driving circuit described in the first embodiment.
The working process of the LED lamp in this embodiment can refer to the description of the first embodiment. The constant current driving circuit is applied to the LED lamp, so that the illumination performance of the LED can be improved.
The embodiments of the present invention have been described in detail with reference to the accompanying drawings, but the present invention is not limited to the above embodiments, and various changes can be made within the knowledge of those skilled in the art without departing from the gist of the present invention. Furthermore, the embodiments of the present invention and the features of the embodiments may be combined with each other without conflict.
Claims (6)
1. An LED constant current driving circuit is characterized by comprising a positive temperature coefficient thermistor, a negative temperature coefficient thermistor, a voltage division circuit, a decoder, an operational amplifier and a first MOS (metal oxide semiconductor) tube;
the output end of the decoder is connected with the input end of the voltage division circuit, the output end of the voltage division circuit is connected with the positive phase input end of the operational amplifier, the negative phase input end of the operational amplifier is respectively connected with one end of the positive temperature coefficient thermistor, one end of the negative temperature coefficient thermistor and the source electrode of the first MOS tube, the other end of the positive temperature coefficient thermistor and the other end of the negative temperature coefficient thermistor are both grounded, the output end of the operational amplifier is connected with the grid electrode of the first MOS tube, and the drain electrode of the first MOS tube is connected with the LED lamp;
one end of the positive temperature coefficient thermistor and one end of the negative temperature coefficient thermistor are also connected with a plurality of branch circuits, each branch circuit comprises a resistor and a connecting end, and the connecting ends can be grounded or suspended.
2. The LED constant current driving circuit according to claim 1, wherein the voltage divider circuit comprises a plurality of MOS transistors, gates of the MOS transistors are correspondingly connected to the output end of the decoder, sources of the MOS transistors are connected to the non-inverting input end of the operational amplifier, and drains of the MOS transistors are grounded.
3. The LED constant current driving circuit according to claim 1, wherein the voltage divider circuit comprises a plurality of MOS transistors, gates of the MOS transistors are correspondingly connected to the output end of the decoder, drains of the MOS transistors are connected to the non-inverting input end of the operational amplifier, and sources of the MOS transistors are grounded.
4. The LED constant-current driving circuit according to claim 2 or 3, wherein the positive temperature coefficient thermistor and the negative temperature coefficient thermistor have opposite thermal characteristics, so that temperature changes can be compensated for each other.
5. The LED constant-current driving circuit according to claim 4, wherein the decoder is a 3-8 decoder, correspondingly, the voltage dividing circuit comprises 8 MOS transistors, and 8 output ends of the 3-8 decoder are respectively connected with gates of the 8 MOS transistors correspondingly.
6. An LED lamp, characterized by comprising the LED constant current drive circuit as claimed in any one of claims 1 to 5.
Priority Applications (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201911368457.7A CN110933811A (en) | 2019-12-26 | 2019-12-26 | LED constant current drive circuit and LED lamp |
| PCT/CN2020/073217 WO2021128527A1 (en) | 2019-12-26 | 2020-01-20 | Led constant-current driving circuit and led lamp |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201911368457.7A CN110933811A (en) | 2019-12-26 | 2019-12-26 | LED constant current drive circuit and LED lamp |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN110933811A true CN110933811A (en) | 2020-03-27 |
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Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN201911368457.7A Pending CN110933811A (en) | 2019-12-26 | 2019-12-26 | LED constant current drive circuit and LED lamp |
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| Country | Link |
|---|---|
| CN (1) | CN110933811A (en) |
| WO (1) | WO2021128527A1 (en) |
Family Cites Families (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP5482221B2 (en) * | 2010-01-22 | 2014-05-07 | 株式会社リコー | Analog circuit |
| CN102542979A (en) * | 2011-11-08 | 2012-07-04 | 南京微盟电子有限公司 | Constant current light emitting diode (LED) driving circuit |
| CN103687201B (en) * | 2013-11-21 | 2015-07-08 | 浙江大学 | Constant-current drive system of LED string lights |
| CN104656732B (en) * | 2014-12-31 | 2016-05-18 | 格科微电子（上海）有限公司 | Voltage reference circuit |
| CN107479617B (en) * | 2017-09-20 | 2023-08-08 | 广西师范大学 | High-precision correction circuit for band-gap reference voltage source |
| CN108693913A (en) * | 2018-05-21 | 2018-10-23 | 上海华力集成电路制造有限公司 | The current generating circuit of temperature coefficient adjustable section |
-
2019
- 2019-12-26 CN CN201911368457.7A patent/CN110933811A/en active Pending
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2020
- 2020-01-20 WO PCT/CN2020/073217 patent/WO2021128527A1/en active Application Filing
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| WO2021128527A1 (en) | 2021-07-01 |
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