46results about How to "Constant output current" patented technology

The invention discloses a switching power supply controller for constant current driving of an LED by primary side control, a method for the constant current driving of the LED and a switching power supply formed by using the switching power supply controller. The switching power supply controller comprises an oscillator circuit, an input alternating current average value calculating circuit, a conduction time control circuit, a logic control circuit and a driving circuit. The controller controls the constant current driving of the LED by using a primary side control method to realize same output current and high power factor under the condition with controlled silicon dimming and high-low voltage input; and transformer isolation is directly used, so that the safety performance of the circuits is improved, a peripheral circuit is simple, the circuit cost is reduced, and the PCB (printed circuit board) distribution space is very small in favor of product miniaturization.

The invention relates to an LED direct-current input control circuit which comprises an input detecting circuit, a voltage increasing circuit and a voltage decreasing circuit which are connected in sequence and also comprises a feedback circuit. The voltage increasing circuit and the voltage decreasing circuit are used for increasing and decreasing the voltage of an inputted direct-current signaland outputting the voltage to supply power to an LED lamp, and the feedback circuit is connected with the voltage decreasing circuit and is used for controlling the constant voltage and the constant current of an output signal. After detecting that the inputted direct-current signal has overvoltage, the input detecting circuit outputs a first overvoltage shutting-off signal to the voltage increasing circuit so as to directly output the inputted direct-current signal to the voltage decreasing circuit to decrease the voltage and supply power to the LED lamp, and after detecting that the inputted direct-current signal has undervoltage, the input detecting circuit outputs an undervoltage shutting-off signal to the voltage increasing circuit and the voltage decreasing circuit so as to shut offthe voltage increasing circuit and the voltage decreasing circuit and carry out undervoltage protection to the voltage increasing circuit and the voltage decreasing circuit. The LED direct-current input control circuit can realize the direct-current input of low voltage and wide range and has the input undervoltage and overvoltage function, the constant current outputting function and the output overvoltage protection function.

The present application provides a control device for controlling a switching converting module to generate an output signal of constant output current from a rectified AC power supply signal. The switching converting module comprises a primary winding for receiving the rectified AC power supply signal and a power switch coupled in series with the primary winding. The control device comprises: an AGC amplifier configured to receive a first sampling signal sampled from the rectified AC power supply signal, and to generate a reference signal of constant amplitude according to the first sampling signal; a signal comparator configured to compare the reference signal with a current sensing signal in proportion to a primary side current flowing through the primary side winding to generate a comparison signal; a signal generator configured to receive a second sampling signal sampled from the output signal, and to generate a clock signal according to the second sampling signal; and a control logic configured to generate a control signal for switching the power switch according to the comparison signal and the clock signal.

The invention discloses a switching power supply controller for constant current driving of an LED by primary side control, a method for the constant current driving of the LED and a switching power supply control device formed by using the switching power supply controller. The switching power supply controller consists of an input dimming angle detection circuit, a multiplier, an on-signal control circuit, a zero-crossing detection circuit, a comparer, a trigger and a driving circuit. A circuit controls the constant current driving of the LED by using a primary side control method to realize same output current and high power factor under the condition with controlled silicon dimming and high-low voltage input; and transformer isolation is directly used, so that the safety performance of the circuit is improved, a peripheral circuit is simple, the circuit cost is reduced, and the PCB (printed circuit board) distribution space is very small in favor of product miniaturization.

The invention discloses a method for implementing a charge pump keeping constant output current, and the charge pump thereof. The method comprises the following steps of: comparing external input voltage of a charge pump main body circuit with reference voltage, and inputting a comparison result into a clock generating circuit to output corresponding clock oscillation frequency, so that the charge pump main body circuit outputs constant current. The output of the charge pump main body circuit is connected to an enable end of the charge pump main body circuit through a voltage feedback and comparison circuit. The external voltage is dynamically detected, and when the external voltage changes, corresponding clock oscillation frequency can be selected according to the external input voltage,so that the charge pump outputs constant current. Therefore, the output voltage ripple of the charge pump is reduced, and the output voltage stability is improved. The charge pump is simple in implementation mode and structure and low in cost.

The invention provides an efficient wide-range voltage regulation SP/S resonance compensation electric automobile wireless charging topological structure which has small conduction loss, an efficient system, a simple circuit structure and good stability. The structure comprises a transmitting terminal circuit, a receiving terminal circuit and a boosting circuit; the transmitting terminal circuit comprises a DC power supply, a full-bridge inverter circuit, a series-parallel resonance compensation network and a transmitting terminal coil; the receiving terminal circuit comprises a receiving terminal coil, a series resonance compensation network, and a single-phase full-bridge rectifier; the boosting circuit comprises a capacitance Ca which is in parallel connection at an output end of the rectifier, an inductance Lt and a regulating switch S which are in series connection at two ends of the capacitance Ca, a diode D which is connected to the junction point of the inductance Lt and the regulating switch S, and a capacitance Cb which is connected between the junction point of the inductance Ld and the regulating switch S and a load end which is corresponding to the diode D; the cathode of the diode D and the other end of the regulating switch S are the load end which is connected with a load R.

The invention discloses an LED intelligent dynamic control system and a control method. The system comprises a central control unit, an adjustable constant current unit and a voltage and current detection unit, wherein the adjustable constant current unit is connected with a control output port and a load of the central control unit, and the voltage and current detection unit is connected with a control input port of the central control unit. The method comprises the following steps of S1, initializing the control system and configuring a minimum current output by an adjustable constant current module; S2, gradually increasing output current of the adjustable constant current module until voltages at both ends of the load are rated voltages; S3, locking an output current value at the time by the control system; and S4, detecting the load and variation of load current and voltage in real time and carrying out dynamic adjustment by the control system. Through a microprocessor technology and a real-time detection technology, the invention dynamically processes the load and the variation of the load current and voltage value, automatically carries out dynamic control according to the variation condition to enable the output current to be constant and can display a work state of the load through four LEDs.

The invention discloses a power supply module feedback control circuit with double functions of constant current and constant voltage, and belongs to a semiconductor integrated circuit. The power supply module feedback control circuit with double functions of constant current and constant voltage comprises a voltage stabilizer TL431, a first operational amplifier U1, a second operational amplifierU2, a third operational amplifier U3, a fourth operational amplifier U4, a sampling resistor R and a diode D1; a power supply module can work in a constant voltage mode or a constant current mode bysetting a control end; when the power supply module works in the constant current mode, the control circuit is used for controlling current output by the power supply module, the output current is guaranteed to be constant, and the value of the output current is given by an external control signal; and when the power supply module works in the constant voltage mode, the control circuit is used forcontrolling output voltage of the power supply module, the output voltage is guaranteed to be constant, and the power supply module can serve as a DC/DC converter for direct current voltage conversion.

A light emitting diode (LED) driver apparatus is provided. The LED driver apparatus includes an input unit, a PWM signal generation unit, a DC-DC converter, an LED driving unit, and a synchronization unit. The input unit is configured to receive a dimming signal. The PWM signal generation unit is configured to generate a PWM signal using an oscillator having a preset frequency. The DC-DC converter is configured to provide a driving voltage to an LED array using the generated PWM signal. The LED driving unit is configured to drive the LED array using the received dimming signal. The synchronization unit is configured to reset the oscillator based on a driving state of the LED array.

The invention discloses a constant-current driving electronic transformer, which is arranged outside a lamp. The electronic transformer is connected to the outer side of the lamp and connected with a high-frequency switch and a control circuit and a voltage-converting circuit through an alternating current/direct current rectifying circuit at the same time. The voltage-converting circuit is connected with an output rectifying circuit. The alternating current/direct current rectifying circuit consists of a bridge-type rectifying circuit which is formed by connecting four diodes, and a parallelly-connected high-voltage electrolytic capacitor. The output rectifying circuit rectifies the current into a direct-current output voltage for driving the connected lamp in the constant-current driving mode. The high-frequency switch and the control circuit are connected with an output constant-current control circuit. An output overvoltage protection circuit consisting of voltage-stabilizing diodes is arranged between the output rectifying circuit and the output constant-current control circuit. In the constant-current driving electronic transformer, conversion between alternating current and direct current is realized and the circuit is relatively simple, the constant-current driving electronic transformer is connected outside the lamp, directly drives the lamp by the constant current, is constant in output current, causes no glint of the lamp and has the functions of short-circuit protein and overheating protection.

The invention relates to an LED driver based on Sepic soft switching and a hybrid driving method thereof. The driver comprises a sampling circuit, a control chip, a driving circuit, a boosting unit I,a boosting unit II, a voltage source Vin, an inductor L1, a switching tube Q1, a capacitor CP, a diode DP, a capacitor Cs, an inductor L3, a diode Do, an output capacitor Co, a sampling resistor Rrefand a diode RL. The PWM + PFM hybrid control method is designed for the LED driver with the dimming function, it can be guaranteed that the output current is constant when the load changes, the mainswitching tube is in a soft switching state all the time, and the loss of the system under high-frequency work is reduced.

A dimmable switching mode LED driving circuit without phase angle measurement, including: a dimmer circuit for providing a phase-cut AC voltage; a bridge rectifier providing an input voltage by rectifying the phase-cut AC voltage; an electromagnetic interference filtering and energy storing circuit providing a line voltage according to the input voltage; a switching power converter converting the line voltage to an output current for an LED load under a control of a driving voltage; and a control unit using at least one feedback signal to perform a pulse width modulation operation to determine an on time for the switching voltage; wherein the control unit includes an on-time controller and a timer, the on-time controller determining the on time according to the at least one feedback signal, and the timer setting a maximum limit on the on time.

The invention discloses a new energy automobile DC charger output regulation and control circuit and a power supply protection control method. The circuit comprises a first filtering module, a voltageregulating module, a second filtering module, an over-current protection module, a resonance circuit module and a voltage stabilization constant-current output control module. An inductor L1 and a capacitor C1 in the first filtering module form a filtering circuit, and ripples in rectified output voltage are filtered out. A pin 1 of a variable resistor RV2 is moved in the voltage regulating module to change the resistance value of the resistor so as to reduce the passing voltage. An inductor L3 and an inductor L4 in the second filtering module are used for screening and filtering the adjustedelectric signals. A resistor R9 in the overcurrent protection module absorbs the electric energy stored in the capacitor C10 to prevent overlarge discharge current. A triode Q2 in the resonance circuit module controls voltage conduction to increase resonance impedance so as to realize voltage gain. A bidirectional silicon controlled rectifier U4 in the voltage stabilization constant current output control module receives an electric signal output by a charger through a pin 1 to realize voltage conduction so as to protect and control an output power supply.

A band gap reference circuit is configured by connecting an emitter of a transistor, having the base and the collector thereof grounded, to an internal circuit, and by connecting an emitter of another transistor, having the base and the collector thereof grounded, to the internal circuit via a resistor having a positive temperature dependence with respect to the absolute temperature, so as to ensure that a constant output current with a small temperature dependence can be generated, without providing any voltage-current conversion circuit and without generating a constant output voltage, while suppressing expansion in the circuit scale but based on a circuit configuration allowing lowering in the power source voltage.

The invention relates to a linear constant current drive mode of an LED signal lamp for an automobile, which belongs to the field of electric illumination. The linear constant current drive mode comprises that a linear constant current control module is arranged between a direct current supply and the LED signal lamp for the automobile connected with the direct current supply and provides linear constant current drive for the LED signal lamp for the automobile, wherein the linear constant current control module comprises a voltage-stabilizing unit, a protective unit and an executing unit; and at the stage that the value of the working current of the LED signal lamp is lower than that of set current, the forward working current of an LED generates linear change following the change of input power supply voltage. After the working current of the LED reaches the set working current, the working current of the LED is set at a setting value by a constant current way; and after the value of the working current of the LED is larger than the setting value, the working current of the LED does not generate linear increase following the increase of the power supply voltage, and current outputted by a load is constant. The linear constant current drive mode has the advantages of simple current structure and low production cost, and is particularly suitable for the linear constant current drive of the LED signal lamp of a low current automobile. In addition, the linear constant current drive mode prevents heavy current from damaging the LED.

The invention belongs to an electro-hydraulic servo valve testing technology, particularly relates to a current output driver achieving deep negative feedback, wide range output and adjustable precision, and belongs to the technical field of testing. The invention provides a torque motor driver for electro-hydraulic servo valve testing. The toque motor driver comprises a box, a coil positive and negative connector assembly, an ammeter, a power switch, a power socket, a precision potentiometer and an integrated circuit plate. The torque motor driver achieves deep negative feedback, wide range output and adjustable precision and has a digital display function, so that the requirements of electro-hydraulic servo valve torque motor performance testing are met, wherein the requirements are that carrying is convenient, 220 V alternating current power supply is achieved, a dual-redundancy electro-hydraulic servo valve can be driven, the output current range ranges from -400 mA to 400 mA, and the precision is manually adjusted from -1 mA to 1 mA.