Constant-current output BUCK power circuit
A power supply circuit, constant current output technology, applied in the direction of converting DC power input to DC power output, output power conversion devices, electrical components, etc., can solve the problem of inconstant output current and achieve the effect of improving stability
Inactive Publication Date: 2015-04-15
UNIV OF ELECTRONICS SCI & TECH OF CHINA
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Problems solved by technology
[0006] The present invention aims at the problem that the output current is not constant in the prior art, and proposes a constant current output BUCK power supply circuit, so that the output current remains unchanged when the input and output voltages and output inductance change
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[0022] In this example, the structure of the constant current output BUCK power supply circuit is as follows Figure 4 As shown, it includes a pulse circuit, a control unit, a driving unit, a first transistor Q1, a freewheeling diode D1, an output inductor L1, an output capacitor C1, a sampling resistor R1, and a constant current control circuit. Among them, the pulse circuit, the control unit, and the drive unit have the power of the traditional BUCK power circuit control chip, which is used to generate a signal for controlling the on and off of the first transistor, and adjust the output voltage and current according to the feedback signal of the sampling resistor. The constant current control circuit of this example includes a first operational amplifier A1, a second operational amplifier A2, an inverter U1, an AND gate U2, a second transistor Q2, a third transistor Q3, and a second capacitor C2. In this example, the first transistor is a power field effect transistor, which ...
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The invention relates to a switch power circuit working in a BUCK mode and discloses a constant-current output BUCK power circuit which aims to solve the problem of inconstant output current of the prior art. According to the technical scheme, the constant-current output BUCK power circuit comprises a control chip, a switch tube, a fly-wheel diode, an output inductor, an output capacitor and a sampling resistor, wherein the control chip is composed of a pulse circuit, a control unit and a drive unit and used for generating a signal which controls turn-on and turn-off of the switch tube and adjusting the output voltage and an output current according to a feedback signal of the sampling resistor. The constant-current output BUCK power circuit is characterized by further comprising a constant current control circuit, wherein the constant current control circuit comprises a first operational amplifier, a second operational amplifier, an inverter, an and gate, a second transistor, a third transistor and a second capacitor. The constant-current output BUCK power circuit solves the problem that the output current is influenced by the input voltage, the output voltage and output inductance value and greatly improves stability of the output current.
Description
Technical field [0001] The invention relates to a DC-DC (direct current-direct current) converter, in particular to a switching power supply circuit working in a BUCK mode (buck conversion mode). Mainly used for driving power of LED light source. Background technique [0002] Nowadays, high-efficiency, energy-saving, and environmentally friendly light sources have become a universal requirement of society. LED is a new type of energy-saving light source widely used in recent years. Since LEDs are characteristic-sensitive semiconductor devices, the requirements of LEDs for driving power are almost harsh. The current commonly used drive circuit is based on the BUCK circuit, and the first transistor in the BUCK circuit is controlled by the control chip to control the turn-on and turn-off time of the first transistor to control and stabilize the output current. [0003] Such as figure 1 Shown: a traditional output constant current circuit based on switching power supply BUCK topolog...
Claims
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IPC IPC(8): H02M3/156
Inventor 方健赵前利王贺龙李源彭宜建潘华谷洪波
Owner UNIV OF ELECTRONICS SCI & TECH OF CHINA