Dual voltage operated LED light strip

Abstract

The utility model discloses a kind of LED lamp strips of double-voltage operation, including first lamp string, second lamp string, triode Q1, triode Q2 and triode Q3, the anode of first lamp string is connected with power input end, cathode is connected with the anode of second lamp string in series connection;The gate of triode Q3 is connected with power input end through voltage stabilizing diode Z3, drain electrode is connected with the gate of triode Q1 and triode Q2 respectively;The gate of triode Q1 is connected with power input end through resistance R1, source electrode is connected with the anode of second lamp string;The gate of triode Q2 is connected with power input end through resistance R2, drain electrode is connected with the cathode of first lamp string.The utility model makes LED lamp strip work under double-voltage condition by pure circuit structure, without relying on comparator or special control chip, greatly simplify circuit structure, reduce hardware cost and production complexity.

Description

Technical Field

[0001] This utility model relates to a lighting device, and more particularly to a driving circuit for an LED light strip. Background Technology

[0002] Patent document CN116471721A discloses a linear constant current control circuit based on automatic switching of LED lamp modes. The technical solution includes a load component and a series-parallel switching module, a current switching module, and an efficiency detection module connected to the load component. By detecting the loss voltage on the first load, the circuit calculates the working efficiency based on the loss voltage and determines the appropriate power supply voltage value to drive the series-parallel switching module to turn on or off its branches, allowing the first and second loads to be connected in parallel or series. The circuit automatically adjusts the series-parallel connection mode of the LED group based on the working efficiency of the LEDs, thus enabling operation under different voltages. However, this circuit structure involves acquiring the loss voltage on the first load using a comparator or chip and comparing it with a switching reference voltage, then outputting a parallel or series signal based on the comparison result. The overall circuit structure is relatively complex. Utility Model Content

[0003] In order to overcome the shortcomings of the existing technology, this utility model provides an LED light strip that operates under dual voltage.

[0004] The technical solution adopted by this utility model to solve its technical problem is: A dual-voltage LED light strip includes: a first light string, a second light string, transistors Q1, Q2, and Q3. The positive terminal of the first light string is connected to a power input terminal, and its negative terminal is connected in series with the positive terminal of the second light string. The gate of transistor Q3 is connected to the power input terminal through a Zener diode Z3, and the drain of transistor Q3 is connected to the gates of both transistors Q1 and Q2. The gate of transistor Q1 is connected to the power input terminal through a resistor R1, and its source is connected to the positive terminal of the second light string. The gate of transistor Q2 is connected to the power input terminal through a resistor R2, and its drain is connected to the negative terminal of the first light string.

[0005] This application employs a simple control circuit. Compared to existing technologies, it does not require a comparator or a dedicated control chip. Specifically, under low-voltage conditions, the voltage at the power input terminal is lower than that of the Zener diode Z3, causing Z3 to be cut off. This cuts off transistor Q3, which in turn turns on transistor Q2 powered by resistor R2. The negative terminal of the first LED string is grounded through transistor Q2, illuminating the first LED string. Simultaneously, transistor Q1 is powered by resistor R1 and turns on. The positive terminal of the second LED string is connected to the power input terminal through transistor Q1, illuminating the second LED string. At this time, the first and second LED strings form a parallel structure. Under high-voltage conditions, the voltage at the power input terminal is higher than that of the Zener diode Z3, causing transistor Q3 to turn on powered by the power input terminal. This forces transistors Q1 and Q2 to be pulled low and cut off, short-circuiting their circuits. This causes the first and second LED strings to form a series circuit, illuminating them simultaneously.

[0006] As a further improvement of this utility model, the first light string and the second light string are each composed of a number of light-emitting diodes connected in series. The first light string is connected in series with a current-limiting resistor RL1, and the second light string is connected in series with a current-limiting resistor RL2.

[0007] As a further improvement of this utility model, the source of the transistor Q3 is grounded, and a Zener diode Z4 and a resistor R4 are connected in parallel between the source and gate of the transistor Q3.

[0008] As a further improvement of this utility model, an isolation diode D3 is connected between the source of the transistor Q1 and the positive terminal of the second lamp string, and a Zener diode Z1 is connected between the source and gate of the transistor Q1.

[0009] As a further improvement of this utility model, the source of the transistor Q2 is grounded, a Zener diode Z2 is connected between the source and gate of the transistor Q2, and an isolation diode D2 is connected between the gate of the transistor Q2 and the drain of the transistor Q3.

[0010] As a further improvement of this utility model, an isolation diode D1 is connected in series between the first light string and the second light string.

[0011] The beneficial effects of this invention are as follows: This invention enables LED light strips to operate under dual voltage conditions through a pure circuit structure, eliminating the need for comparators or dedicated control chips, thus significantly simplifying the circuit structure and reducing hardware costs and production complexity. Under low voltage input, the circuit automatically switches the two light strings to parallel mode, and under high voltage input, it automatically switches to series mode, ensuring stable operating current and brightness of the light strings under both voltage conditions. Attached Figure Description

[0012] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0013] Figure 1 This is the circuit schematic diagram of this utility model. Detailed Implementation

[0014] To make the objectives, technical solutions, and advantages of this utility model clearer, the present utility model will be further described in detail below with reference to specific embodiments and accompanying drawings. It should be noted that, unless otherwise specified, the embodiments and features of the present utility model can be combined with each other.

[0015] It should be understood that these descriptions are merely exemplary and are not intended to limit the scope of this invention.

[0016] The following describes some embodiments of the present invention with reference to the accompanying drawings.

[0017] Reference Figure 1 A dual-voltage LED light strip includes: a first light string 1, a second light string 2, transistors Q1, Q2, and Q3. The positive terminal of the first light string 1 is connected to a power input terminal, and its negative terminal is connected in series with the positive terminal of the second light string 2. The gate of transistor Q3 is connected to the power input terminal through a Zener diode Z3, and the drain of transistor Q3 is connected to the gates of transistors Q1 and Q2. The gate of transistor Q1 is connected to the power input terminal through a resistor R1, and the source of transistor Q1 is connected to the positive terminal of the second light string 2. The gate of transistor Q2 is connected to the power input terminal through a resistor R2, and the drain of transistor Q2 is connected to the negative terminal of the first light string 1.

[0018] In this embodiment, the transistor can be a switching transistor or a MOSFET, which are transistors with turn-off or turn-on functions.

[0019] This invention enables LED light strips to operate under dual voltage conditions through a pure circuit structure, eliminating the need for comparators or dedicated control chips. This significantly simplifies the circuit structure and reduces hardware costs and production complexity. Under low voltage input, the circuit automatically switches the two light strings to parallel mode, and under high voltage input, it automatically switches to series mode, ensuring stable operating current and brightness of the light strings under both voltage conditions.

[0020] Specifically, under low voltage conditions, the voltage at the power input terminal is lower than that of the Zener diode Z3, causing Z3 to be cut off. This cuts off transistor Q3, which in turn turns on transistor Q2 powered by resistor R2. The negative terminal of the first LED string is grounded through transistor Q2, illuminating the first LED string 1. Simultaneously, transistor Q1 is powered by resistor R1 and turns on. The positive terminal of the second LED string 2 is connected to the power input terminal through transistor Q1, illuminating the second LED string 2. At this time, the first LED string 1 and the second LED string 2 form a parallel structure. Under high voltage conditions, the voltage at the power input terminal is higher than that of the Zener diode Z3, causing transistor Q3 to turn on powered by the power input terminal. This forces transistors Q1 and Q2 to be pulled low and cut off, short-circuiting their circuits. This causes the first LED string 1 and the second LED string 2 to form a series circuit, illuminating them simultaneously.

[0021] In this embodiment, the power input terminal is the DC voltage VCC after AC power is rectified. The low voltage can be 100V and the high voltage can be 220V. Since the peak voltage of AC voltage is 1.4 times the effective value, the peak voltage of 100V AC power is 140V. Therefore, the voltage regulation value of Zener diode Z3 can be selected as 150V. Increasing it by 10V can be used as a control margin.

[0022] The first light string 1 and the second light string 2 are each composed of several light-emitting diodes connected in series. The first light string 1 is connected in series with a current-limiting resistor RL1, and the second light string 2 is connected in series with a current-limiting resistor RL2.

[0023] The source of transistor Q3 is grounded, and a Zener diode Z4 and a resistor R4 are connected in parallel between the source and gate of transistor Q3. An isolation diode D3 is connected between the source of transistor Q1 and the positive terminal of the second lamp string 2, and a Zener diode Z1 is connected between the source and gate of transistor Q1. The source of transistor Q2 is grounded, and a Zener diode Z2 is connected between the source and gate of transistor Q2. An isolation diode D2 is connected between the gate of transistor Q2 and the drain of transistor Q3. In this embodiment, the Zener diodes Z1, Z2, and Z4 serve a voltage limiting function, regulating the voltage to 5-20V, protecting the switching transistors Q1, Q2, and Q3 from high voltage breakdown.

[0024] In this embodiment, the Zener diode Z4 can be omitted. A resistor is connected between one end of the Zener diode Z3 and the source of the transistor Q3. Since there are few Zener diodes, and even fewer high-voltage ones, adding a resistor for voltage reduction makes it possible to eliminate the need for a high-voltage Zener diode Z3, making voltage adjustment more convenient and voltage switching more efficient.

[0025] An isolation diode D1 is connected in series between the first light string 1 and the second light string 2. In series mode, this allows unidirectional current conduction, ensuring that the two light strings form a stable series circuit. In this embodiment, isolation diodes D1, D2, and D3 serve as voltage isolation diodes, with a withstand voltage requirement of 500V or higher.

[0026] Although embodiments of the present invention have been shown and described, those skilled in the art will understand that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the present invention, the scope of which is defined by the claims and their equivalents.

Claims

1. A dual-voltage LED light strip, characterized in that... include: The first light string (1), the second light string (2), transistors Q1, Q2 and Q3 are connected together. The positive terminal of the first light string (1) is connected to the power input terminal, and the negative terminal is connected in series with the positive terminal of the second light string (2). The gate of transistor Q3 is connected to the power input terminal through Zener diode Z3, and the drain of transistor Q3 is connected to the gates of transistors Q1 and Q2 respectively. The gate of transistor Q1 is connected to the power input terminal through resistor R1, and the source of transistor Q1 is connected to the positive terminal of the second light string (2). The gate of transistor Q2 is connected to the power input terminal through resistor R2, and the drain of transistor Q2 is connected to the negative terminal of the first light string (1).

2. The LED light strip operating under dual voltages according to claim 1, characterized in that... The first light string (1) and the second light string (2) are each composed of several light-emitting diodes connected in series. The first light string (1) is connected in series with a current-limiting resistor RL1, and the second light string (2) is connected in series with a current-limiting resistor RL2.

3. The LED light strip operating under dual voltages according to claim 1, characterized in that... The source of the transistor Q3 is grounded, and a Zener diode Z4 and a resistor R4 are connected in parallel between the source and gate of the transistor Q3.

4. The LED light strip operating under dual voltages according to claim 1, characterized in that... An isolation diode D3 is connected between the source of the transistor Q1 and the positive terminal of the second lamp string (2), and a Zener diode Z1 is connected between the source and the gate of the transistor Q1.

5. The LED light strip operating under dual voltages according to claim 1, characterized in that... The source of transistor Q2 is grounded, and a Zener diode Z2 is connected between the source and gate of transistor Q2. An isolation diode D2 is connected between the gate of transistor Q2 and the drain of transistor Q3.

6. The LED light strip operating under dual voltages according to claim 1, characterized in that... An isolation diode D1 is connected in series between the first light string (1) and the second light string (2).

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