45results about How to "Good constant current effect" patented technology

The invention relates to a high-efficiency LED constant current driving circuit. The circuit comprises an input rectification filter circuit, a switch power supply management chip, an isolation switch transformer, a primary clamping circuit of the transformer, an output rectification filter circuit, an output current sampling circuit, a reference voltage generation circuit, a comparison circuit and a photoelectrical coupling circuit, wherein the input end of the input rectification filter circuit is connected with commercial AC electricity, while the output end is connected with a primary winding of the isolation switch transformer through the switch power supply management chip; the primary clamping circuit of the transformer is connected in parallel with the primary winding of the isolation switch transformer; the input end of the output rectification filter circuit is connected with the primary winding of the isolation switch transformer, while the output end is connected with LED load; an output current sampling circuit is connected in series with the LED load; the input end of the reference voltage generation circuit is connected with the LED load; and the input end of the comparison circuit is connected with the output current sampling circuit and the reference voltage generation circuit, while the output end is connected with the switch power supply management chip through the photoelectrical coupling circuit. The circuit improves the circuit integration degree, the reliability, the constant current precision and the circuit conversion efficiency.

The invention relates to a light-emitting diode (LED) dimming driving system with a silicon controlled bypass dimming circuit. The LED dimming driving system with the silicon controlled bypass dimming circuit comprises an alternating current/direct current (AC/DC) LED constant current actuator and a LED light string, wherein the input end of the AC/DC LED constant current actuator is electrically connected with an alternating current electric supply, the output end of the AC/DC LED constant current actuator is connected with the LED light string, the silicon controlled bypass dimming circuit is arranged, the input end of the silicon controlled bypass dimming circuit is connected with the alternating current (AC) electric supply, and the output end of the silicon controlled bypass dimming circuit is connected with a dimming interface of the AC/DC LED constant current actuator. The AC/DC LED constant current actuator obtains energy from the AC electric supply, and outputs a constant current value to drive the LED light string. The AC/DC LED constant current actuator is provided with an analog dimming interface which is used for adjusting an output current value according to an analog voltage amplitude value of an input dimming signal so as to change luminance of the LED light string. According to the silicon controlled bypass dimming circuit, the input end of the silicon controlled bypass dimming circuit is connected with the AC electric supply, and the output end of the silicon controlled bypass dimming circuit generates a smooth direct current analog voltage signal to serve as a dimming signal which is input into the analog dimming interface of the AC/DC LED constant current actuator. The value of amplitude of the dimming signal output by the silicon controlled bypass dimming circuit can be adjusted by adjusting an adjustable knob of the silicon controlled bypass dimming circuit, and thus a current value and the luminance of the LED light string can be adjusted.

This invention discloses a uniform and constant current method for parallel democratic bus, which compares current signals of constant branches with bus mean value and suppresses the branches with current exceeding the mean value, and carries out constant control to the general current by the constant current branches to reach the aim of mean distribution of the branches and constant general current, at the same time, the branches have their independent protection circuit and common indication to fault.

The invention discloses a voltage-following type depth negative feedback constant current source device which comprises an input rectification filtering unit, a DC-AC inversion unit, an output rectification filtering unit, a linear constant current adjusting tube and a load which are connected in sequence, wherein the input rectification filtering unit is connected with an alternative current power supply; the load is respectively connected with a voltage sampling unit and a current sampling unit; the voltage sampling unit is connected with a PWM voltage control unit connected with the DC-AC inversion unit; the current sampling unit is connected with a constant current control unit connected with the linear constant current adjusting tube. On the basis of the conventional constant current source circuit, the PWM power supply control unit is added, so that the voltage of a control power supply changes along with the change of the load, and the voltage drop on the linear constant current adjusting tube is constantly kept at a constant value, therefore, the device has the advantages of good constant current effect, high precision and rapid response of the constant current source circuit, and but also has the advantages of high circuit efficiency of a switch power supply, small power consumption, low temperature rise and high reliability.

The invention discloses an LED constant current source output detection control circuit and a control method thereof, and relates to the technical field of LED driving power sources. The LED constant current source output detection control circuit comprises an output load, an inductor L2, a chip U2, a power switch tube Q2, a resistor R1 and a resistor R2. One end of the inductor L2 is connected to the drain of the power switch tube Q2, and the connection line is provided with a connection node. The chip U2 is provided with a pin VCC, a pin VDET and a pin DRV. The grid of the power switch tube Q2 is connected to the pin DRV. One end of the resistor R2 is connected to the pin VDET, and the other end of the resistor R2 is connected to the connection node. One end of the resistor R1 is connected to the pin VCC, and the other end of the resistor R1 is connected to the common end of the pin VDET and the resistor R2. The LED constant current source output detection control circuit and the control method thereof have the advantages that the demagnetization time of the inductor can be instantly obtained, output voltage and input voltage are detected, and the constant current effect and reliability of a system are improved.

The invention relates to a voltage compensation circuit and method for a constant-current system. The constant-current system comprises a BUCK topological structure circuit, wherein the BUCK topological structure circuit comprises a load and a switch tube; the output voltage of the constant-current system is the voltage of the two ends of the load; and the voltage compensation circuit is used for generating a control signal which is linearly relevant to the output voltage to control the switch-on and switch-off of the switch tube according to the control signal so as to further keep an arithmetic product of the output voltage and the switch-on time of the switch tube approximately constant to output constant current. Due to the adoption of the voltage compensation method, the constant-current effect of the output current is greatly improved; and the voltage compensation method can be widely applied to an analog integrated circuit which needs to obtain constant current.

The invention relates to a high precision LED constant current drive unit which comprises an inductor (L) which is in series connection with a luminescence LED lamp (LED), a sampling resistor (RS), and a first field effect transistor (M1). The high precision LED constant current drive unit also comprises a power driving module (U3), a retardation comparator (U2), a first amplifier (U1) and an inductance current sampling unit which are electrically connected with a grid of the first field effect transistor in order. Two input terminals of the inductance current sampling unit are electrically connected with two ends of the sampling resistor, and an output terminal of the inductance current sampling unit is electrically connected with a first input terminal of first amplifier and a first input terminal of the retardation comparator. A second input terminal of the retardation comparator is electrically connected with an output terminal of the first amplifier. A second input terminal of the first amplifier is electrically connected with a voltage references unit. The LED constant current drive unit has a good constant current effect, is insensitive to changes of input/output voltage, and can work with high frequency without sacrificing constant current precision. And a volume of an illumination system is reduced.

The invention relates to a closed-loop control LED (Light Emitting Diode) constant-current driving circuit, which comprises an inductor (L), a sampling resistor (RS) and a power switch (M1), wherein the inductor (L) and the sampling resistor (RS) are connected with an external LED light source (LED1) in series; and the power switch (M1) is used for disconnecting/conducting a power channel of the external LED light source (LED1). The closed-loop control LED constant-current driving circuit is characterized by further comprising a sampling and amplifying unit (U1), an error amplifier (U2), a comparator (U3), an oscillator (U4), a latching and triggering unit and a power switch driving unit (U6) electrically connected with two ends of the sampling resistor (RS) in sequence; the closed-loop control LED constant-current driving circuit further comprises a frequency compensation unit for ensuring steady loop; and the output end of the power switch driving unit (U6) is electrically connected with the control end of the power switch (M1). The closed-loop control LED constant-current driving circuit disclosed by the invention has fixed switch frequency and good constant-current effect.

The invention discloses a constant current DC (Direct Current)-DC converter utilizing digital PWM (Pulse-Width Modulation) control and a constant current LED (Light Emitting Diode) drive DC-DC converter. The constant current DC-DC converter utilizing digital PWM control comprises a power level and a digital PWM control level which are electrically connected, as well as a constant current control level electrically connected with the power level and the digital PWM control level respectively. The constant current DC-DC converter utilizing digital PWM control and the constant current LED drive DC-DC converter disclosed by the invention can overcome defects in the prior art, such as complex structure, high cost, large power consumption and low conversion efficiency, so as to realize the advantages of simple structure, low cost, small power consumption, good constant current effect and high conversion efficiency.

The invention discloses a low-power LED illuminating lamp, comprising a current-limiting capacitor, a rectifier bridge, a parallel capacitor and an LED lamp, wherein the current-limiting capacitor is connected between the electric supply and a bridge type rectifier in series, the output end of the bridge type rectifier is connected with the LED lamp, and a non-polarity and non-electrolyte capacitor is connected to the output end of the bridge type rectifier in parallel. In the invention, the rectified pulse direct current is used for directly driving the beads of the small-power LED lamp to illuminate by the function of high-internal resistance and self-current limitation function of the small-capacity non-electrolyte capacitor, and both ends of the bead string of the LED lamp are connected with a small-capacity non-electrolyte capacitor and the current-limiting capacitor in parallel for branching voltage to prevent overvoltage instantly generated during switching on a power supply from damaging the beads of the LED lamp. The invention greatly prolongs the service life of the LED lamp, has the advantages of high reliability, low cost, high efficiency, minor power consumption and long service life, and can also be used as a backlight source of a television, a display screen, a notebook computer and the like for illumination.

The invention provides a primary constant current circuit of an inverter welding machine. The primary constant current circuit comprises a major loop and a control loop; the major loop comprises a double-pipe single-end forward circuit mainly comprising power switches Q3 and Q5, clamping diodes D3 and D4, a high-frequency isolation transformator T1, a sampling transformer T2, commutation diodes D10 and D11, free-wheeling diodes D12, D13 and D15 and an inductor L2; the control loop comprises two circuits, one circuit is a welding machine output short-circuit protection circuit, and in the other circuit, through regulation of a PI regulating circuit, a pulse signal output through a control signal can constantly regulate the pulse duty cycle, so that a welding machine can output constant current. According to the primary constant current circuit, the primary circuit is additionally arranged at the inverter welding machine, so that the constant current output characteristic of the welding machine is realized.

The invention discloses an LED light supplement control circuit used for a roller-shutter-type shutter exposure camera. The circuit comprises a light supplement lamp source, a power supply circuit portion and a control circuit portion. The power supply circuit portion comprises a rectifier B, a flyback switch conversion circuit K and an output filtering energy storage capacitor C13 which are successively connected. The control circuit portion comprises a flyback switch conversion control circuit DL1, a low voltage conversion direct current circuit DL2, an output voltage control circuit DL3, a power control circuit DL4, a MAX485 conversion circuit DL5, a single chip microcomputer control circuit DL6 and a trigger logic circuit DL7. The circuit has advantages that a trigger response speed is rapid; a constant current effect of a LED light source is good; and constant bright power of an LED light supplement lamp source and high light power during a light supplement process can be set.

The invention relates to a light-emitting diode (LED) white light lamp, in particular to a three-primary-color-principle-based ultra-high-brightness LED white light mixing method. The method is characterized in that: an inner seat, a shell, and a drive circuit are at least involved; red, green and blue (RGB) LEDs are distributed on the inner seat in a proportion; a shell is covered on the inner seat; and light emitted by the RGB LEDs covers a condensation surface of the shell through a reflection surface A in the shell at a distributed divergence angle under the action of the drive circuit, and then is mixed to form white light, and the white light is softened by the condensation surface and then the white light with required color temperature is emitted outward. The invention provides the three-primary-color-principle-based ultra-high-brightness LED white light mixing method in which the radiating effect is good, process mixing manufacturability is high and a drive circuit is simple.

The invention discloses a novel scheme of electronic circuit design and application. The invention has the core contents that a common three-end adjustable voltage stabilizing device is applied to a constant-current circuit of an automobile ignition module and the obtained product is matched with a small amount of passive devices to replace a conventional automobile ignition module constant-current circuit so as to enable the circuit to be more simple and reliable; in the working process, the constant-current performance is more stable and the temperature characteristic is better. The scheme can be used for various types of ignition module constant-current control circuits and also can be suitable for ignition module circuits of which the output levels adopt power tubes (darlington tubes or IGBT ((Insulated Gate Bipolar Transistor)) with different characteristics.

The invention discloses an LED light source structure with an LED driving function. The LED light source with the LED driving function comprises a heat-conducting base and LED light source panels. The heat-conducting base is designed to be in the shape of a regular prismoid with the middle portion protruding. The upper end face and the side faces of the heat-conducting base are covered with the LED light source panels, so that a light-emitting surface which is approximately conical is formed. The LED light source panel on the upper portion emits light in a planar mode, and the LED light source panels on the side faces emit light all around, so that the light outlet angle is large, the light is uniform, the lighting effect is excellent, and dark regions are avoided. The heat-conducting base is hollow, and the bottom of the heat-conducting base is open. An LED driving circuit is installed in an inner cavity of the heat conducting base. A bottom cover is installed at the bottom of the heat-conducting base. The LED driving circuit is fixed to the bottom cover. The LED driving circuit and an LED light source are combined into a whole, so that the integrity is good, the structural design is reasonable, and assembly of the lamp is facilitated. A constant-current diode is adopted by the LED driving circuit for achieving constant currents, and light emitting is stable.