High-power LED lamp driving circuit

Abstract

A high-power LED lamp driving circuit comprises a controller, an LED lamp, a constant current source circuit, a first switch tube, a second switch tube and a third switch tube. The anode end and the cathode end of the LED lamp are respectively connected with an input voltage and a constant current source circuit, and the LED lamp is composed of a first LED lamp string, a second LED lamp string and a third LED lamp string which are sequentially connected between the anode end and the cathode end in series. A first control signal output interface, a second control signal output interface and a third control signal output interface of the controller are connected with controlled ends of a first switch tube, a second switch tube and a third switch tube respectively, the first switch tube, the second switch tube and the third switch tube are connected with a first LED lamp string, a second LED lamp string and a third LED lamp string respectively, and a first conduction end and a second conduction end of each switch tube are connected with an anode and a cathode of the corresponding LED lamp string respectively. According to the utility model, the implementation cost is low, and the constant current source circuit for providing current for the LED lamp is ensured not to be derated.

Description

Technical Field

[0001] This utility model relates to LED lamp driver circuits. Background Technology

[0002] In automotive ambient lighting applications, some special tri-color ambient lights are used for warning purposes. These lights require high brightness, thus necessitating high current draw. To meet these brightness requirements, the driver circuit for this type of tri-color ambient light typically uses multiple constant current sources connected in parallel to amplify the current flowing through the red, green, and blue LEDs, thereby achieving high brightness. This approach places high demands on the number of constant current source channels in the LED driver chip, increasing manufacturing costs. Summary of the Invention

[0003] The technical problem to be solved by this utility model is to provide a high-power LED lamp driver circuit that has low implementation cost and can ensure that the constant current source circuit supplying current to the LED lamp will not be derated.

[0004] To solve the above-mentioned technical problems, the technical solution adopted by this utility model is as follows:

[0005] The high-power LED lamp driving circuit of this utility model embodiment includes a controller, an LED lamp, and a constant current source circuit. The anode and cathode terminals of the LED lamp are respectively connected to the input voltage and the constant current source circuit. The LED lamp is composed of a first to a third LED lamp string connected in series between the anode and cathode terminals. The high-power LED lamp driving circuit also includes a first to a third switching transistor. The first to a third control signal output interfaces of the controller are respectively connected to the controlled terminals of the first to a third switching transistor. The first to a third switching transistor are respectively connected in parallel with the first to a third LED lamp string. The first conducting terminal and the second conducting terminal of each switching transistor are respectively connected to the anode and cathode of the corresponding LED lamp string.

[0006] After adopting the above technical solution, this utility model has at least the following advantages and features:

[0007] The high-power LED lamp driving circuit of this utility model uses a single external constant current source circuit to provide operating current for the LED lamp, eliminating the requirement for the number of constant current source channels of the controller and reducing implementation costs. By controlling the three switching transistors connected in parallel with the three LED lamp strings respectively through the controller, the three switching transistors are not turned off at the same time, which can prevent the three LED lamp strings from being lit at the same time at any time. This can eliminate the phenomenon of derating of the external constant current source circuit (i.e., the current output by the constant current source circuit is lower than the rated current) due to low input voltage. Attached Figure Description

[0008] Figure 1A schematic block diagram of a high-power LED lamp driving circuit according to an embodiment of the present invention is shown.

[0009] Figure 2 A circuit diagram of a high-power LED lamp driver circuit according to an embodiment of the present invention is shown. Detailed Implementation

[0010] The present invention will now be described in detail with reference to the accompanying drawings and specific embodiments.

[0011] Figure 1 and Figure 2 The circuit principle of a high-power LED lamp driver circuit according to an embodiment of the present invention is shown below. Please refer to it. Figure 1 and Figure 2 A high-power LED lamp driving circuit 100 according to an embodiment of the present invention includes a controller 1, an LED lamp 2, a constant current source circuit 3, a first switching transistor 41, a second switching transistor 42, a third switching transistor 43, an input terminal circuit 5, and a LIN port protection circuit 6.

[0012] The anode and cathode of LED 2 are connected to the input voltage VS1 and the constant current source circuit 3, respectively. LED 2 consists of a first LED string 21, a second LED string 22, and a third LED string 23 connected in series between the anode and cathode. Each LED string consists of a single LED or multiple LEDs of the same color connected in the same direction. The term "high power" in this application means that the rated power of the LED is greater than or equal to 1.5W (0.5W for each LED string).

[0013] In some specific implementation methods, such as Figure 2 As shown, LED light 2 is a three-color ambient light. The first LED light string 21, the second LED light string 22, and the third LED light string are red LED light string, green LED light string, and blue LED light string, respectively.

[0014] The constant current source circuit 3 is a transistor constant current source circuit, which includes NPN transistors Q5 and Q4, resistors R1 and R2. The collector of NPN transistor Q5 is connected to the cathode of LED 2. The base of NPN transistor Q5 is connected to the common junction of the first end of resistor R2 and the collector of NPN transistor Q4. The emitter of NPN transistor Q5 is connected to the common junction of the first end of resistor R1 and the base of NPN transistor Q4. The second end of resistor R1 and the emitter of NPN transistor Q4 are both grounded. The second end of resistor R2 is connected to the input voltage VS1. After NPN transistor Q4 is turned on, the conduction voltage of resistor R1 is limited by the base-emitter voltage Vbe4 of NPN transistor Q4. The current flowing through LED 2 is approximately Vbe4 / R1 of NPN transistor Q4.

[0015] The power input interface VS2 of controller 1 is connected to the input voltage VS1. The first control signal output interface LED0, the second control signal output interface LED1 and the third control signal output interface LED2 of controller 1 are respectively connected to the controlled terminals of the first switch 41, the second switch 42 and the third switch 43. The first switch 41, the second switch 42 and the third switch 43 are respectively connected in parallel with the first LED string 21, the second LED string 22 and the third LED string 23. The first conducting terminal and the second conducting terminal of each switch are respectively connected to the anode and cathode of the corresponding LED string.

[0016] In this embodiment, the first switch 41, the second switch 42, and the third switch 43 are respectively composed of a first PNP transistor Q1, a second PNP transistor Q2, and a third PNP transistor Q3. The base, emitter, and collector of the PNP transistors constitute the controlled terminal, the first conducting terminal, and the second conducting terminal of the switch, respectively. In other embodiments, the first switch 41, the second switch 42, and the third switch 43 are each composed of a PMOS transistor. Preferably, the operating parameters of the first switch 41, the second switch 42, and the third switch 43 are the same (for PNP transistors, this means that the base-emitter voltage and collector-emitter voltage of the first PNP transistor Q1, the second PNP transistor Q2, and the third PNP transistor Q3 are all the same).

[0017] In this embodiment, controller 1 is a microcontroller U1. Controller 1 uses a TCPL010A automotive ambient light driver chip manufactured by Techsilicon Technologies Inc.

[0018] Input circuit 5 includes diode D101, TVSD102, capacitor C101, and capacitor C102. LIN port protection circuit 6 includes ESD TVSD103, ferrite bead B101, capacitor C104, and capacitor C105. The output of LIN port protection circuit 6 is connected to the LIN transceiver of controller 1.

[0019] The input power supply KL30, after passing through the anti-reverse diode D101, provides power (input voltage VS1) to the microcontroller U1, the constant current source circuit 3, and the LED 2. Specifically, when the first control signal output interface LED0 of the controller 1 is turned on (i.e., LED0 is in the on state) and draws sufficient current, the PNP transistor Q1 is saturated and conducts. At this time, the current flows through the PNP transistor Q1 and not through the first LED string 21; that is, when the switching transistor is in the on state, it can bypass the LED string connected in parallel with the switching transistor. When the first control signal output interface LED0 of the controller 1 is turned off, it is in an open-drain state, the PNP transistor Q1 is not conducting, and the current flows through the first LED string 21. The working principle of the second control signal output interface LED1 and the third control signal output interface LED2 is the same as that of LED0.

[0020] When the input voltage is too low (e.g., below 9V), since the first to third LED strings are connected in series to the collector of NPN transistor Q5, if all three LED strings are lit, the collector voltage of NPN transistor Q5 will be too low, causing it to enter saturation. This will derating the constant current source circuit 3, preventing it from working properly and thus affecting the brightness of LED 2. In this embodiment, a switching transistor is connected in parallel next to each LED string. By controlling the switching transistor to be on, a bypass function is achieved, preventing the LED strings connected in parallel with that transistor from lighting up. That is, the controller of the high-power LED driver circuit in this embodiment controls the first to third switching transistors to not be turned off simultaneously (the three light-emitting control signals sent to LED0, LED1, and LED2 are not simultaneously at a low level), thus preventing the first to third LED strings from being lit simultaneously and eliminating the derating phenomenon of the external constant current source circuit 3 due to low input voltage.

[0021] The high-power LED lamp driving circuit of this utility model embodiment uses a single external constant current source circuit to provide operating current to the LED lamp, eliminating the requirement for the number of constant current source channels in the controller and reducing manufacturing costs.

Claims

1. A high-power LED lamp driving circuit comprising a controller, an LED lamp and a constant current source circuit, an anode terminal and a cathode terminal of the LED lamp being connected with an input voltage and the constant current source circuit respectively, the LED lamp being composed of first to third LED lamp strings which are connected in series in turn between the anode terminal and the cathode terminal; characterized in that, The high-power LED lamp driving circuit further comprises first to third switching tubes; The first to third control signal output interfaces of the controller are connected with the controlled ends of the first to third switching tubes respectively, and the first to third switching tubes are connected with the first to third LED lamp strings in parallel respectively, wherein the first conducting end and the second conducting end of each switching tube are connected with the anode and the cathode of the corresponding LED lamp string respectively.

2. The high power LED lamp driving circuit according to claim 1, wherein, The constant current source circuit is a triode constant current source circuit, which comprises an NPN triode Q5, an NPN triode Q4, a resistor R1 and a resistor R2. The collector of the NPN triode Q5 is connected with the cathode of the LED lamp, the base of the NPN triode Q5 is connected with the common connection point of the first end of the resistor R2 and the collector of the NPN triode Q4, and the emitter of the NPN triode Q5 is connected with the common connection point of the first end of the resistor R1 and the base of the NPN triode Q4. The second end of the resistor R1 and the emitter of the NPN triode Q4 are grounded, and the second end of the resistor R2 is connected with the input voltage.

3. The high power LED lamp driving circuit according to claim 1, wherein, The first to third switching tubes are all PNP triodes, and the base, the emitter and the collector of the PNP triode respectively constitute the controlled end, the first conducting end and the second conducting end of the switching tube.

4. The high power LED lamp driving circuit according to claim 1 or 3, characterized in that, The working parameters of the first to third switching tubes are the same.

5. The high power LED lamp driving circuit according to claim 1, wherein, The power input interface of the controller is connected with the input voltage.

6. The high power LED lamp driving circuit according to claim 1 or 5, wherein The controller is a single-chip microcomputer.

7. The high power LED lamp driving circuit of claim 1, wherein, The LED lamp is a three-color atmosphere lamp, and the first to third LED lamp strings are red LED lamp string, green LED lamp string and blue LED lamp string respectively.

8. The high power LED lamp driving circuit according to claim 1 or 7, characterized in that, The controller selects a driving chip for automobile atmosphere lamp produced by Taisi Micro Company, and the model of the driving chip is TCPL010A.

9. The high power LED lamp driving circuit according to claim 1 or 7, wherein, Each LED lamp string is composed of a single LED lamp bead or a plurality of same-direction series LED lamp beads with the same color.

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