CN111372353A - Proportional current source circuit, LED drive circuit, car light and vehicle - Google Patents
Proportional current source circuit, LED drive circuit, car light and vehicle Download PDFInfo
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Abstract
The present disclosure provides a proportional current source circuit, wherein the proportional current source circuit includes: a plurality of proportional current devices configured to provide proportional currents to a respective plurality of circuit branches, respectively; and a switching circuit configured to cut power to the plurality of proportional current devices in response to a trip signal of at least one of the plurality of circuit branches; wherein one of the circuit branches is used as a power supply circuit branch, and the output end of the power supply circuit branch supplies power to the switch circuit.
Description
Technical Field
The present disclosure relates to the field of electronic devices, and in particular, to a proportional current source circuit, and an LED driving circuit, a vehicle lamp, and a vehicle including the proportional current source circuit.
Background
Proportional current source circuits are widely used in various electronic circuits for providing a desired constant current. More specifically, proportional current source circuits are commonly used in lighting circuits to provide illumination. However, how to ensure the safety of an electronic circuit such as a lighting circuit while supplying a constant current to any of a plurality of circuit branches in the electronic circuit is a hot issue of attention in recent years.
It is therefore desirable to provide a proportional current source circuit that is capable of providing a constant current to a plurality of circuit branches of an electronic circuit while ensuring the safety of the electronic circuit.
Disclosure of Invention
According to a first aspect of embodiments of the present invention, there is provided a proportional current source circuit, wherein the proportional current source circuit includes: a plurality of proportional current devices configured to provide proportional currents to a respective plurality of circuit branches, respectively; and a switching circuit configured to cut power to the plurality of proportional current devices in response to a trip signal of at least one of the plurality of circuit branches; wherein one of the circuit branches is used as a power supply circuit branch, and the output end of the power supply circuit branch supplies power to the switch circuit.
Such a configuration can avoid placing the switching circuit in the power loop, thereby avoiding operating the switching circuit in a linear mode. Therefore, the power consumption of the entire circuit is reduced.
In one example, the proportional current source circuit further comprises: the input end of the branch detection circuit is respectively connected with the other circuit branches except the power supply circuit branch in the plurality of circuit branches, and the output end of the branch detection circuit is connected with the control end of the switch circuit; wherein the branch detection circuit is configured to: controlling the switching circuit to cut off power to the plurality of proportional current devices in response to a trip signal of at least one of the remaining circuit branches.
Due to the branch detection circuit, the states of a plurality of circuit branches can be detected, and the power supply of a plurality of proportional current devices can be controlled according to the detection result.
In another example, the branch detection circuit is further configured to: outputting a high voltage to a control terminal of the switching circuit in response to the low voltage output by the at least one of the remaining circuit branches; the switching circuit is further configured to: cutting off power to the plurality of proportional current devices in response to the high voltage received at the control terminal.
The branch detection circuit configured as above is capable of outputting a low voltage in the case where each circuit branch operates normally, and outputting a high voltage in the case where an abnormality occurs in the circuit branch. Therefore, not only can the monitoring of a plurality of circuit branches be realized, but also the branch detection circuit configured as above also has the effect of saving electricity because the normal state is the output low voltage.
In another example, the branch detection circuit includes a plurality of diodes, a first resistor, a second resistor, a first transistor, and an auxiliary power supply, wherein the first resistor and the second resistor are connected in series between the auxiliary power supply and ground, cathodes of the plurality of diodes are connected as input terminals of the branch detection circuit to output terminals of respective ones of the remaining circuit branches, respectively, and anodes are connected to a connection point between the auxiliary power supply and the first resistor; the first transistor is a high-conduction transistor, a base of the first transistor is connected with a connection point between the first resistor and the second resistor, an emitter of the first transistor is connected with the ground, and a collector of the first transistor is connected with a control end of the switch circuit as an output end of the branch detection circuit.
The branch detection circuit adopting the scheme can realize NAND logic by a relatively simple circuit structure so as to achieve the purpose of monitoring the state of each circuit branch.
In another example, the branch detection circuit includes a plurality of input sub-circuits, a first resistor, a second resistor, a first transistor, and an auxiliary power supply, wherein the first resistor and the second resistor are connected in series between the auxiliary power supply and ground, input terminals of the plurality of input sub-circuits are connected as input terminals of the branch detection circuit to output terminals of respective ones of the remaining circuit branches, respectively, and output terminals are connected to a connection point between the first resistor and the second resistor; the first transistor is a high-conduction transistor, and a base of the first transistor is connected to a connection point between the first resistor and the second resistor, an emitter is connected to ground, and a collector is connected to a control terminal of the switch circuit as an output terminal of the branch detection circuit, wherein each input sub-circuit is configured to output a low voltage in response to a break of a corresponding circuit branch.
In another example, each input sub-circuit comprises a first sub-resistor, a second sub-resistor, a third sub-resistor, a first sub-transistor and a second sub-transistor, and the first sub-transistor and the second sub-transistor are high-conducting transistors, one end of the first sub-resistor is connected with the corresponding circuit branch as the input end of the corresponding input sub-circuit, and the other end of the first sub-resistor is connected with the base electrode of the first sub-transistor; an emitter of the first sub-transistor is grounded and a collector is connected to an auxiliary power supply via a third sub-resistor; the second sub-resistor is connected between the emitter and the base of the first sub-transistor; and the base of the second sub-transistor is connected to the collector of the first sub-transistor, the emitter is grounded and the collector serves as the output end of the corresponding input sub-circuit.
With the scheme of this example, since no diode is present in the circuit, detection errors due to reverse breakdown of the diode can be avoided. Therefore, the branch detection circuit according to this example can output a detection result with higher reliability.
In another example, the switching circuit includes a second transistor; the second transistor is a low conduction type transistor, the base of the second transistor is used as the control end of the switch circuit and is connected with the output end of the branch detection circuit, the collector of the second transistor is connected with the control ends of the proportional current devices, and the emitter of the second transistor is connected with the output end of the branch of the power supply circuit to receive power supply.
In another example, the switch circuit further includes a third transistor, which is a high-conduction transistor, having a base connected to the collector of the second transistor, an emitter connected to the control terminals of the plurality of proportional current devices, and a collector connected to a power supply.
With this scheme, the third transistor can further amplify the signal generated by the second transistor, thereby enabling the signal to be sufficient to drive the plurality of proportional current devices.
In another example, the plurality of proportional current devices include a plurality of high-conduction transistors having bases connected as control terminals of the plurality of proportional current devices to the output terminals of the switching circuit, collectors connected to the output terminals of the respective circuit branches, respectively, and emitters grounded.
In another example, the plurality of proportional current devices further includes a plurality of resistors, emitters of the plurality of high-conduction transistors are grounded via the plurality of resistors, respectively, and the plurality of proportional current devices are configured to: providing a proportional current to the plurality of circuit branches based on a ratio of resistance values between the plurality of resistors.
With this scheme, proportional currents can be supplied as needed by selecting the resistance values of the resistors of each circuit branch when designing the circuit.
According to a second aspect of an exemplary embodiment of the present invention, there is provided an LED driving circuit including the proportional current source circuit according to any one of the above examples.
According to a third aspect of exemplary embodiments of the present invention, there is provided a vehicle lamp including the LED driving circuit according to any one of the above examples.
According to a fourth aspect of example embodiments of the invention, there is provided a vehicle employing the lamp according to any one of the examples described above.
Drawings
For a more complete understanding of the present disclosure and the advantages thereof, reference is now made to the following descriptions taken in conjunction with the accompanying drawings, in which:
fig. 1 and 2 respectively show an example of a proportional current source circuit applied to an LED driving circuit according to the prior art;
fig. 3A and 3B respectively show block diagrams of structures of a proportional current source circuit according to an example embodiment of the present disclosure;
fig. 4A and 4B respectively show schematic diagrams of circuits when a proportional current source circuit according to an exemplary embodiment of the present disclosure is applied to an LED driving circuit; and
fig. 5A and 5B respectively show specific examples of the branch detection circuit when the proportional current source circuit according to the exemplary embodiment of the present disclosure is applied to the LED driving circuit.
Detailed Description
Hereinafter, embodiments of the present disclosure will be described with reference to the accompanying drawings. It should be understood that the description is illustrative only and is not intended to limit the scope of the present disclosure. Moreover, in the following description, descriptions of well-known structures and techniques are omitted so as to not unnecessarily obscure the concepts of the present disclosure.
The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the disclosure. The words "a", "an" and "the" and the like as used herein are also intended to include the meanings of "a plurality" and "the" unless the context clearly dictates otherwise. Furthermore, the terms "comprises," "comprising," and the like, as used herein, specify the presence of stated features, steps, operations, and/or components, but do not preclude the presence or addition of one or more other features, steps, operations, or components.
It will be understood by those skilled in the art that various elements may be modified by the ordinal numbers of the terms "first" and "second", etc. However, such elements are not limited to the above words. For example, the above terms do not limit the order and/or importance of the elements. The above terms are only used to distinguish one element from another. For example, a first element could be termed a second element, and, similarly, a second element could be termed a first element, without departing from the scope of the present disclosure.
All terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art unless otherwise defined. It is noted that the terms used herein should be interpreted as having a meaning that is consistent with the context of this specification and should not be interpreted in an idealized or overly formal sense.
Some block diagrams and/or flow diagrams are shown in the figures. It will be understood that some blocks of the block diagrams and/or flowchart illustrations, or combinations thereof, can be implemented by computer program instructions. These computer program instructions may be provided to a processor of a general purpose computer, special purpose computer, or other programmable data processing apparatus, such that the instructions, which execute via the processor, create means for implementing the functions/acts specified in the block diagrams and/or flowchart block or blocks.
Fig. 1 and 2 respectively show examples of a proportional current source circuit applied to an LED driving circuit according to the related art.
According to the prior art, the proportional current source circuit shown in fig. 1 is often used to supply power to each circuit branch in the LED driving circuit. The proportional current source circuit includes a proportional current device Q providing a proportional current1、Q2、...、QNAnd R1、R2、...、RNFor driving a corresponding number (i.e., N, if any) of LED circuit branches. Although the solution of fig. 1 can achieve the objective of feeding a constant current to any number of LED circuit branches, it has some problems. In particular, the proportional current source circuit lacks protection for the LED driver circuit. That is, when a branch of a certain LED circuit is disconnected, the power supply to the other branches of the LED circuit cannot be cut off, which may damage the circuit.
Based on this, an LED driving circuit shown in fig. 2 is proposed. In the LED driving circuit shown in fig. 2, compared to the proportional current source circuit used in fig. 1, there is no improvement on the proportional current source circuit for driving, and the avoidance of damage to the LED driving circuit is achieved by only adding a feedback control switch (such as the transistor M1 shown in fig. 2) to the LED driving circuit. However, since the LED driving circuit needs to be feedback controlled and the feedback control switch is a three-port device, the LED driving circuit can only be used to drive two circuit branches. Specifically, a feedback control switch is provided in a power circuit of one circuit branch in the LED driving circuit and receives a feedback signal from the other circuit branch, thereby controlling the supply of power. That is, the proportional current mirror circuit shown in fig. 2 is only capable of supplying a drive current to the two-way circuit branches and cutting off the current feed to the other circuit branch in the event of an open circuit of any of the two-way circuit branches for protection. Furthermore, since the feedback-controlled switch is provided in the power loop of the circuit branch, the feedback-controlled switch may sometimes operate in a linear mode, resulting in large power consumption.
In order to at least partially solve the above problems, it is necessary to provide a new proportional current source circuit.
Fig. 3A and 3B respectively illustrate block diagrams of a proportional current source circuit 300 according to an example embodiment of the present disclosure.
As shown in fig. 3A, a proportional current source circuit 300 is provided. The proportional current source circuit 300 includes: a plurality of proportional current devices 310-1, 310-2, 310-N, the plurality of proportional current devices 310-1, 310-2, 310-N configured to provide proportional currents to a respective plurality of circuit branches, respectively; and a switch circuit 320, the switch circuit 320 configured to disconnect power to the plurality of proportional current devices 310-1, 310-2, · g, 310-N in response to a trip signal of at least one of the plurality of circuit branches; wherein one of the circuit branches is a power supply circuit branch (as shown in the figure, the first circuit branch), and the output end of the power supply circuit branch supplies power to the switch circuit 320. Compared to the circuit configuration shown in fig. 2, such a configuration can avoid placing the switch circuit 320 in the power loop, thereby avoiding operating the switch circuit in the linear mode. Therefore, the power consumption of the entire circuit is reduced.
Alternatively, in another embodiment, the proportional current source circuit 300 may further include: the branch detection circuit 330 is shown in FIG. 3B. The input end of the branch detection circuit 330 is connected to the other circuit branches except the power supply circuit branch, and the output end of the branch detection circuit 330 is connected to the control end of the switch circuit 320. The branch detection circuit 330 may be configured to: controlling the switching circuit 320 to cut power to the plurality of proportional current devices 310-1, 310-2, …, 310-N in response to a trip signal for at least one of the remaining circuit branches.
For example, the branch detection circuit 330 may be further configured to: in response to the low voltage output by the at least one of the remaining circuit branches, a high voltage is output to the control terminal of the switch circuit 320, i.e., nand logic is implemented. At this time, the switching circuit 320 may be further configured to: cutting off power to the plurality of proportional current devices 310-1, 310-2, …, 310-N in response to the high voltage received at the control terminal.
It should be noted that although the branch detection circuit 330 is illustratively described herein as a circuit for implementing nand logic, those skilled in the art will recognize that the structure and corresponding functionality of the branch detection circuit 330 is not so limited. For example, it may be a circuit configured to output a low voltage to the control terminal of the switch circuit 320 in response to the low voltage output by the at least one of the remaining circuit branches. At this time, the switching circuit 320 may be further configured to: cutting off power to the plurality of proportional current devices 310-1, 310-2, …, 310-N in response to a low voltage received at the control terminal.
That is, the branch detection circuit 330 and the switch circuit 320 may be configured by those skilled in the art according to actual conditions, as long as the switch circuit 320 is ensured to output a corresponding signal to cut off the power supply to the plurality of proportional current devices 310-1, 310-2, …, 310-N in case that the branch detection circuit 330 detects that at least one circuit branch is short-circuited.
Fig. 4A and 4B respectively show schematic diagrams of circuits when the proportional current source circuit according to the exemplary embodiment of the present disclosure is applied to an LED driving circuit.
In the circuits shown in FIGS. 4A and 4B, the plurality of proportional current devices 310-1, 310-2, …, 310-N illustratively include a plurality of high-conductivity transistors Q1、Q2、...、QnAnd a plurality of resistors R1、R2、...、Rn. The plurality of high-conductivity transistors Q1、Q2、...、QnAs control terminals of the plurality of proportional current devices 310-1, 310-2, …, 310-N, a base (i.e., a b pole) thereof is connected to an output terminal of the switching circuit 320, a collector (i.e., a c pole) thereof is connected to an output terminal of the corresponding circuit branch, respectively, and an emitter (i.e., an e pole) thereof is connected to an output terminal of the corresponding circuit branch via the plurality of resistors R, respectively1、R2、...、RnAnd (4) grounding. Those skilled in the art will recognize that the plurality of proportional current devices 310-1, 310-2, …, 310-N are configured to: based on the plurality of resistors R1、R2、...、RnTo provide proportional current to the plurality of circuit branches. In particular, it will be appreciated by those skilled in the art that the respective current ratios may be obtained by adjusting the resistance values of the respective resistors. For example, if R is to be1Is selected to be R2Is 2 times the resistance value of and is RNOne third of the resistance value of (1), then R1The current of the circuit branch should be R2The current of the circuit branch is one half and is RNThe current of the circuit branch is 3 times. Thus, the resistor R can be selected1、R2、...、RnTo provide the required proportional current to the plurality of circuit branches.
In addition, one skilled in the art will also recognize when there are multiple resistors R1、R2、...、RnThe proportional current source circuits shown in fig. 4A and 4B become current mirror circuits capable of providing balanced currents for the respective circuit branches, that is, the current proportion of the respective circuit branches of the proportional current source circuits is 1 at this time. In addition, it should be noted that the plurality of proportional current devices 310-1, 310-2, …, 310-N shown may also be comprised of a plurality of high-conductivity transistors Q in the case of a current mirror circuit1、Q2、...、QnTo achieve that said plurality of high conduction transistors Q1、Q2、...、QnThe emitter of (2) is directly grounded.
At one endIn one example, the plurality of high-conduction transistors Q1、Q2、...、QnMay be implemented by an N-type transistor, for example, an N-type bipolar transistor.
In addition, in the example circuits shown in fig. 4A and 4B, the branch detection circuit 330 may be implemented by, for example, a circuit that performs nand logic as described above. Similar to fig. 3, the first circuit branch connected to the switching circuit 320 is used as a supply circuit branch for supplying power to said switching circuit 320. The input terminals of the circuit for performing the nand logic may be connected to the output terminals of the second to nth circuit branches other than the first circuit branch, respectively, and the output terminal thereof is connected to the control terminal of the switching circuit 320. In particular, the circuitry executing the nand logic may be further configured to: in response to the at least one of the second through nth circuit branches outputting a low voltage (i.e., a trip signal), a high voltage is output to the control terminal of the switch circuit 320. It should be noted that although in the description of the exemplary embodiment of the present invention, the branch detection circuit 330 is exemplarily shown to be connected to the output terminals of the second to nth circuit branches, those skilled in the art will recognize that the present invention is not limited thereto, and the branch detection circuit 330 may be connected to any number of circuit branches among the first to nth circuit branches to detect the states of the connected circuit branches.
In addition, in the present exemplary embodiment, since the branch detection circuit 330 is exemplarily configured to output a high voltage to the switch circuit 320 in response to at least one circuit branch connected thereto outputting a low voltage, the switch circuit 320 is further configured to: in response to receiving a high voltage at its control terminal, power to the plurality of proportional current devices 310-1, 310-2, …, 310-N is cut off. Specifically, the switch circuit 320 may be implemented by a low-conduction transistor. The low-conduction transistor capable of outputting a low voltage in response to the control terminal receiving a high voltage further causes a plurality of high-conduction transistors Q of the plurality of proportional current devices 310-1, 310-2, …, 310-N1、Q2、...、QnOff, thereby cutting off power to the plurality of proportional current devices 310-1, 310-2, …, 310-N.
In one example, as shown in FIG. 4A, when using, for example, a P-type transistor Qb1To implement the switching circuit 320, the P-type transistor Qb1May be connected as a control terminal of the switch circuit 320 to an output terminal of the branch detection circuit 330, and a collector (i.e., a c-pole) may be connected as the high-conduction transistor Q1、Q2、...、QnIs connected to the base of the control terminal and the emitter (i.e. e-pole) is connected to the output of the supply circuit branch (in this example, the first circuit branch) to receive power. The P-type transistor Qb1Can be turned off in response to a high voltage received at the base, thereby causing the plurality of high-conduction transistors Q to be turned on1、Q2、...、QnOutputs a low voltage, that is, makes a plurality of high-conduction transistors Q1、Q2、...、QnAnd (6) cutting off.
In another example, as shown in fig. 4B, the switch circuit 320 may additionally include a high-conduction transistor QbIts base (i.e., b-pole) and the P-type transistor Qb1Is connected to the collector of the transistor Q, and the emitter (i.e., the e-pole) is connected to the transistor Q as the high conduction type1、Q2、...、QnIs connected to the base of the control terminal of (1), and the collector (i.e., the c-pole) is connected via a resistor RcIs connected with a power supply. In this example, a high-conduction transistor QbCan further amplify the transistor Q of low conduction typeb1A signal generated such that the signal is sufficient to drive a plurality of high-conductivity transistors Q in the plurality of proportional current devices 310-1, 310-2, …, 310-N1、Q2、...、Qn. In addition, the transistor Q is of a high conduction typebEnables proportional currents with higher accuracy to be supplied to the respective circuit branches.
Specifically, the P-type transistor Qb1Can be turned off in response to a high voltage received at the control terminal to thereby make the transistor Q of high conduction typebCut-off. Off high conduction transistor QbFurther controlling the plurality of high-conduction transistors Q1、Q2、...、QnIs low, that is, a plurality of high-conduction transistors Q are made to be high1、Q2、...、QnAnd (6) cutting off. Thus, power to the plurality of proportional current devices 310-1, 310-2, …, 310-N is cut off.
It should be noted that although the branch detection circuit 330 is exemplarily described as a circuit for implementing nand logic in the above example and the following description, a person skilled in the art will recognize that the branch detection circuit 330 is not limited thereto, and may be any other circuit, for example, a circuit configured to output a low voltage to the control terminal of the switch circuit 320 in response to a low voltage output by the at least one of the remaining circuit branches. Further, it should be noted that if the branch detection circuit 330 is configured as a circuit that outputs a low voltage to the control terminal of the switch circuit 320 in response to the low voltage output by the at least one of the remaining circuit branches, the switch circuit 320 may accordingly be further configured to: cutting off power to the plurality of proportional current devices 310-1, 310-2, …, 310-N in response to a low voltage received at the control terminal.
Fig. 5A and 5B respectively show a specific example of the branch detection circuit 330 when the proportional current source circuit according to the exemplary embodiment of the present disclosure is applied to the LED driving circuit.
In the example shown in fig. 5A, the branch detection circuit 330 mainly includes a plurality of diodes D2、D3、...、DnA first resistor RaA second resistor RbA first transistor Qb2And an auxiliary power supply (as shown, +5V auxiliary power supply). In addition, the branch detection circuit 330 may further include a device for optimizing performance and protecting a circuit, etc., for example, a resistor R for resistance matching0And Rb2. The structure and specific operation principle of the branch detection circuit 330 shown in fig. 5A will be described in detail below. The first resistor RaAnd the second electrodeResistor RbConnected in series between the auxiliary power supply and ground. The plurality of diodes D2、D3、...、DnAs an input terminal of the branch detection circuit 330 is connected to an output terminal of a corresponding one of the remaining circuit branches, respectively, and an anode is connected to the auxiliary power supply and the first resistor RaAre connected with each other at the connecting points. The first transistor Qb2Is a high-conduction transistor, and the first transistor Qb2And the first resistor R and the base (i.e., b-pole)aAnd the second resistor RbThe connection point therebetween (corresponding to the node a), the emitter (i.e., the e-pole) is connected to the ground, and the collector (i.e., the c-pole) is connected as the output terminal of the branch detection circuit 330 to the control terminal of the switch circuit 320.
For the branch detection circuit 330 shown in fig. 5A, when each circuit branch is in a normal operating state, the output terminal of each circuit branch outputs a relatively high voltage. Therefore, the voltage of the node A is relatively high, and the node A with the higher voltage is enough for the transistor Qb2Is turned on, and thus, the transistor Qb2A low voltage is output to the switching circuit 320. Transistor Q in response to the base receiving a low voltageb1Is turned on to make the transistor QbAnd conducting. That is, the switching circuit 320 outputs a high voltage to a plurality of proportional current devices 310-1, 310-2, …, 310-N, of which a plurality of high-conductivity transistors Q are included in the plurality of proportional current devices 310-1, 310-2, …, 310-N1、Q2、...、QnTurns on in response to its base receiving a high voltage, thus continuing to supply power.
On the other hand, when at least one of the circuit branches to which the branch detection circuit 330 is connected is open-circuited (e.g., the second circuit branch), the output terminal of the at least one circuit branch outputs a low voltage, i.e., the diode D2Receives a low voltage. At this time, a large amount of current flows through the diode D2Transistor Q not yet turned off temporarily2And a resistor R2Flow to ground such that RaAnd RbThe current between them is small, further, the node A is electrifiedThe pressure is lower. Specifically, the voltage at node a is insufficient to turn on transistor Qb2. Therefore, at this time, the transistor Qb2Output a high voltage to the switching circuit 320, resulting in the transistor Qb1And (6) cutting off. As described above, since the transistor Qb1Is turned off, so that the transistor QbSo that the base of the transistor Q is at a low voltagebAnd is cut off accordingly. In addition, since the transistor QbOff, the switch circuit 320 outputs a low voltage to the plurality of proportional current devices 310-1, 310-2, …, 310-N, resulting in a plurality of high conduction transistors Q1、Q2、...、QnAnd (6) cutting off. Thus, power to the plurality of proportional current devices 310-1, 310-2, …, 310-N is cut off.
In addition, when the power supply circuit branch (e.g., the first circuit branch shown in fig. 1) is disconnected, its output terminal outputs a low voltage and no current flows out. Thus, for transistor Qb1In other words, the voltage between the emitter (i.e., e-pole) and the base (i.e., b-pole) is not sufficient to turn on the PN junction therebetween, i.e., the transistor Qb1And (6) cutting off. As described above, since the transistor Qb1Off, therefore, no current flows into the transistor Qb1Collector (or transistor Q)bBase of) so that transistor QbAnd is cut off accordingly. In addition, since the transistor QbOff, the switch circuit 320 outputs a low voltage to the plurality of proportional current devices 310-1, 310-2, …, 310-N, resulting in a plurality of high conduction transistors Q1, Q2、...、QnAnd (6) cutting off. Thus, power to the plurality of proportional current devices 310-1, 310-2, …, 310-N is cut off.
In the example shown in FIG. 5B, the branch detection circuit 330 basically includes a plurality of input sub-circuits 331-2, 331-3aA second resistor RbA first transistor Qb2And an auxiliary power supply (as shown, +5V auxiliary power supply). The first resistor RaAnd the second resistor RbConnected in series between the auxiliary power supply and ground. The input terminals of the plurality of input sub-circuits 331-2, 331-3The input terminal of the path 330 is connected to the output terminal of the corresponding circuit branch of the other circuit branches, and the output terminal is connected to the first resistor RaAnd the second resistor RbThe connection point between (corresponding to node a) is connected. In this example, each input sub-circuit may be configured to output a low voltage in response to the respective circuit branch being open circuited. Similar to fig. 5A, the first transistor Qb2Is a high-conduction transistor, and the first transistor Qb2And the first resistor R and the base (i.e., b-pole)aAnd the second resistor RbTo ground, and a collector (i.e., a c-pole) as an output terminal of the branch detection circuit 330 to a control terminal of the switch circuit 320.
More specifically, each input sub-circuit comprises a first sub-resistor R21、R31、...、RN1Second sub-resistor R22、R32、...、RN2Third sub-resistor R23、R33、...、RN3First sub-transistor Q21、Q31、...、QN1And a second sub-transistor Q22、Q32、...、QN2. In this example, the first sub-transistor Q21、Q31、...、QN1And a second sub-transistor Q22、Q32、...、QN2Is a high-conduction transistor. The first sub-resistor R21、R31、...、RN1As an input terminal of the respective input sub-circuit, to the respective circuit branch, and to the base (i.e., b-pole) of the first sub-transistor. The emitter (i.e., e-pole) of the first sub-transistor is grounded and the collector (i.e., c-pole) is connected via a third sub-resistor R23、R33、...、RN3Is connected to an auxiliary power supply. The second sub-resistor R22、R32、...、RN2Is connected between the emitter and the base of the first sub-transistor to ensure that the base current is not excessive. The base (i.e., b-pole) of the second sub-transistor is connected to the collector, emitter of the first sub-transistorI.e., the e-pole) is grounded and the collector (i.e., the c-pole) serves as the output of the corresponding input sub-circuit.
The operation of the branch detection circuit 330 shown in fig. 5B is similar to the operation of the branch monitoring circuit 330 shown in fig. 5A.
Specifically, when each circuit branch is in a normal operating state, the output terminal of each circuit branch outputs a relatively high voltage. For example, for the Nth circuit branch, the output voltage of the Nth circuit branch is equal to the output voltage of the transistor QN2When the voltage of the collector of the transistor Q corresponds toN2In normal operation, transistor QN1So that the base voltage of the transistor Q is highN1Is turned on to make the transistor QN2Is low, i.e. transistor QN2And (6) cutting off. Due to the transistor QN2Is turned off, so that the transistor QN2The collector of which cannot be pulled low by the emitter, so that the output of this circuit branch outputs a higher voltage. That is, the voltage at node a is relatively high. Since node a, which has a higher voltage, is sufficient to enable transistor Qb2Is turned on, and thus, the transistor Qb2A low voltage is output to the switching circuit 320. On the other hand, when at least one of the nth circuit branches is disconnected, for example, and the output terminal of the at least one circuit branch outputs a low voltage, the transistor Q is turned onN1The base voltage of (2) is low, so that the transistor QN1Is turned off, so that the transistor QN2Is a high voltage, i.e. transistor QN2And conducting. Due to the transistor QN2Is turned on so that the transistor QN2Is pulled low by its emitter, thereby outputting a low voltage. That is, the voltage at node A is relatively low, which is insufficient to cause transistor Qb2Is turned on, and thus, the transistor Qb2Turns off and outputs a high voltage to the switching circuit 320. When the power supply circuit branch is broken, the operation principle of the circuit shown in fig. 5B is completely the same as that of the circuit shown in fig. 5A, and therefore, the detailed description thereof will be omitted.
In addition, those skilled in the art should note that the configuration of the plurality of proportional current source devices 310-1, 310-2, a.., 310-N, the switching circuit 320, and the LED lighting branch are merely exemplary shown in the circuits shown in FIGS. 5A and 5B, and the branch detection circuit 330 shown in FIGS. 5A and 5B may be used in conjunction with the plurality of proportional current source devices 310-1, 310-2, a.., 310-N and the switching circuit 320 having other configurations as described above, and may also be applied to LED lighting branches or other electronic circuits having other configurations.
In summary, the proportional current mirror circuit according to the above exemplary embodiments can provide a proportional current to each circuit branch, and at the same time, can ensure the safety of each circuit branch. Specifically, the proportional current mirror circuit according to the above-described exemplary embodiment is capable of detecting the state of each circuit branch and cutting off the power supply in the case where any circuit branch or any plurality of circuit branches are disconnected.
According to another aspect of exemplary embodiments of the present invention, there is also provided an LED driving circuit including the proportional current source circuit according to any one of the above examples.
According to a further aspect of exemplary embodiments of the present invention, there is also provided a vehicle lamp including the LED driving circuit according to any one of the above examples.
According to still another aspect of an example embodiment of the present invention, there is also provided a vehicle employing the lamp according to any one of the above examples.
The techniques of this disclosure may be implemented in hardware and/or software (including firmware, microcode, etc.). In addition, the techniques of this disclosure may take the form of a computer program product on a computer-readable medium having instructions stored thereon for use by or in connection with an instruction execution system. In the context of this disclosure, a computer-readable medium may be any medium that can contain, store, communicate, propagate, or transport the instructions. For example, the computer readable medium can include, but is not limited to, an electronic, magnetic, optical, electromagnetic, infrared, or semiconductor system, apparatus, device, or propagation medium. Specific examples of the computer readable medium include: magnetic storage devices, such as magnetic tape or Hard Disk Drives (HDDs); optical storage devices, such as compact disks (CD-ROMs); a memory, such as a Random Access Memory (RAM) or a flash memory; and/or wired/wireless communication links.
The above-mentioned embodiments are intended to illustrate the objects, technical solutions and advantages of the present invention in further detail, and it should be understood that the above-mentioned embodiments are only exemplary embodiments of the present invention, and are not intended to limit the present invention, and any modifications, equivalents, improvements and the like made within the spirit and principle of the present invention should be included in the protection scope of the present invention.
Claims (13)
1. A proportional current source circuit (300), wherein the proportional current source circuit (300) comprises:
a plurality of proportional current devices (310-1, 310-2, 310-N), the plurality of proportional current devices (310-1, 310-2, 310-N) configured to provide proportional currents to a corresponding plurality of circuit branches, respectively; and
a switching circuit (320), the switching circuit (320) configured to cut power to the plurality of proportional current devices (310-1, 310-2, 310-N) in response to a trip signal for at least one of the plurality of circuit branches;
wherein one of the plurality of circuit branches is a supply circuit branch, the switching circuit (320) being supplied by an output of the supply circuit branch.
2. The proportional current source circuit (300) of claim 1, further comprising:
a branch detection circuit (330), wherein the input end of the branch detection circuit (330) is respectively connected with the rest circuit branches except the power supply circuit branch in the plurality of circuit branches, and the output end of the branch detection circuit (330) is connected with the control end of the switch circuit (320); wherein the branch detection circuit (330) is configured to:
controlling the switching circuit (320) to cut power to the plurality of proportional current devices (310-1, 310-2, 310-N) in response to a trip signal for at least one of the remaining circuit branches.
3. The proportional current source circuit (300) of claim 2, wherein the branch detection circuit (330) is further configured to:
outputting a high voltage to a control terminal of the switching circuit (320) in response to the low voltage output by the at least one of the remaining circuit branches;
the switching circuit (320) is further configured to: cutting off power to the plurality of proportional current devices (310-1, 310-2, 310-N) in response to the high voltage received at the control terminal.
4. The proportional current source circuit (300) of claim 3, wherein the branch detection circuit (330) comprises a plurality of diodes (D)2，D3，Dn) A first resistor (R)a) A second resistor (R)b) A first transistor (Q)b2) And an auxiliary power supply for supplying power to the power supply,
wherein the first resistor (R)a) And the second resistor (R)b) Is connected in series between the auxiliary power supply and the ground,
the plurality of diodes (D)2，D3，Dn) As an input of the branch detection circuit (330) is connected to an output of a respective one of the remaining circuit branches, and an anode is connected to the auxiliary power supply and the first resistor (R)a) The connecting points between the two are connected;
the first transistor (Q)b2) Is a high-conduction transistor, and the first transistor (Q)b2) And said first resistor (R)a) And the second resistor (R)b) To ground, and a collector as an output of the branch detection circuit (330) to a control terminal of the switching circuit (320).
5. The proportional current source circuit (300) of claim 3, wherein the branch detection circuit (330) comprises a plurality of input sub-circuits (331-2, 331-3, 331-N), a first resistor(s) (300)Ra) A second resistor (R)b) A first transistor (Q)b2) And an auxiliary power supply for supplying power to the power supply,
wherein the first resistor (R)a) And the second resistor (R)b) Is connected in series between the auxiliary power supply and the ground,
the input terminals of the plurality of input sub-circuits as input terminals of the branch detection circuit (330) are respectively connected with the output terminals of the corresponding circuit branches of the remaining circuit branches, and the output terminals are connected with the first resistor (R)a) And the second resistor (R)b) The connecting points between the two are connected;
the first transistor (Q)b2) Is a high-conduction transistor, and the first transistor (Q)b2) And said first resistor (R)a) And the second resistor (R)b) To ground and a collector as an output of said branch detection circuit (330) to a control terminal of said switching circuit (320),
wherein each input sub-circuit is configured to output a low voltage in response to the respective circuit branch being open circuited.
6. The proportional current source circuit (300) of claim 5, wherein each input sub-circuit comprises a first sub-resistor (R)21，R31，RN1) A second sub-resistor (R)22，R32，RN2) A third sub-resistor (R)23，R33，RN3) A first sub-transistor (Q)21，Q31，QN1) And a second sub-transistor (Q)22，Q32，QN2) And a first sub-transistor (Q)21，Q31，QN1) And a second sub-transistor (Q)22，Q32，QN2) Is a transistor of a high-conduction type,
the first sub-resistor (R)21，R31，RN1) As an input terminal of the respective input sub-circuit, to the respective circuit branch, and to the first sub-transistor (Q)21，Q31，QN1) The base electrodes are connected;
the first sub-transistor (Q)21，Q31，QN1) Is grounded and the collector is connected via a third sub-resistor (R)23，R33，RN3) Is connected to an auxiliary power supply;
the second sub-resistor (R)22，R32，RN2) Is connected to the first sub-transistor (Q)21，Q31，QN1) Between the emitter and the base; and
the second sub-transistor (Q)22，Q32，QN2) Is connected to the first sub-transistor (Q)21，Q31，QN1) With the emitter grounded and the collector as the output of the corresponding input sub-circuit.
7. The proportional current source circuit (300) of claim 2, wherein the switch circuit (320) comprises a second transistor (Q)b1) (ii) a The second transistor (Q)b1) Is a low conduction transistor having a base connected to the output of the branch detection circuit (330) as the control terminal of the switching circuit (320), a collector connected to the control terminals of the plurality of proportional current devices (310-1, 310-2, 310-N), and an emitter connected to the output of the power supply circuit branch to receive power.
8. The proportional current source circuit (300) of claim 7, wherein the switch circuit (320) further comprises a third transistor (Q)b) The third transistor (Q)b) Is a high-conductivity transistor, the base of which is connected to the second transistor (Q)b1) Is connected to the control terminals of the plurality of proportional current devices (310-1, 310-2, 310-N), and is connected to a power supply.
9. The proportional current source circuit (300) of claim 1, wherein the plurality of proportional current devices (310-1, 310-2, 310-N) comprises a plurality of high-conductivity transistors (Q)1，Q2，Qn) Said plurality of high-conductivity transistors (Q)1，Q2，Qn) As control terminals of said plurality of proportional current devices (310-1, 310-2, 310-N) is connected to an output terminal of said switching circuit (320), with respective collectors connected to output terminals of respective circuit branches and with their emitters grounded.
10. The proportional current source circuit (300) of claim 9, wherein the plurality of proportional current devices (310-1, 310-2, 310-N) further comprises a plurality of resistors (R)1，R2，Rn) Said plurality of high-conductivity transistors (Q)1，Q2，Qn) Respectively via the plurality of resistors (R)1，R2，Rn) Is grounded, and
the plurality of proportional current devices (310-1, 310-2, 310-N) are configured to: based on the plurality of resistors (Q)1，Q2，Qn) To provide proportional current to the plurality of circuit branches.
11. An LED driver circuit comprising the proportional current source circuit (300) of any of claims 1 to 10.
12. A vehicular lamp comprising the LED driving circuit according to claim 11.
13. A vehicle employing the lamp according to claim 12.
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201811586100.1A CN111372353A (en) | 2018-12-24 | 2018-12-24 | Proportional current source circuit, LED drive circuit, car light and vehicle |
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| Application Number | Priority Date | Filing Date | Title |
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| CN201811586100.1A CN111372353A (en) | 2018-12-24 | 2018-12-24 | Proportional current source circuit, LED drive circuit, car light and vehicle |
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