4536 results about "Constant current source" patented technology

The present invention is directed to a fluorescent light fixture assembly including a ballast and a novel lighting element that includes an array of LEDs and at least one converter module that enables the existing ballast providing an AC power input to supply DC power to the LED array. The lighting element includes a body that contains the LED array and the converter modules and shares the configuration of the lighting element that is to be retrofitted. The lighting element receives power from the pre-existing ballast, wherein the converter module provides a constant current source to power the LED array. Thus, the lighting element, including the converter module, replaces the conventional fluorescent light tube in a cost-effective retrofit manner with the existing ballast.

A novel and advantageous power supply is disclosed for lighting systems employing semiconductor light sources where the semiconductor light sources are connected in series. The power supply includes a constant current source to supply current to the semiconductor light sources and a bypass switch is provided around each semiconductor light source, or each sub-string of series connected semiconductor light sources. By opening or closing respective bypass switches, individual semiconductor light sources or sub-strings of semiconductor light sources can be illuminated or extinguished as desired. If the bypass switches are electrically controllable, such as semiconductor switches or relays, failures of one or more semiconductor light sources can be determined by the power supply and failed light sources can be bypassed and/or redundant semiconductor elements illuminated to replace failed light sources. Further, if the bypass switches are semiconductor switches, the power supply can employ pulse width modulation techniques to dim one or more semiconductor light sources as desired.

The invention discloses a battery managing system (BMS) testing platform comprising a testing platform main control computer, a high-precision cell voltage simulator, a high-precision large-current constant-current source, a high-precision thermotank, a battery managing system to be tested, a whole vehicle controller simulator and the like which are connected by CAN buses. The battery managing system is connected with a cell box air cooling device, a vehicle relay assembly and the like. The battery managing system testing platform can truly simulate the output state of a battery, comprising single cell voltage, total voltage, charging and discharging current, temperature and the like of the battery, can complete various communication and command functions, protection functions, battery heavy current applying process between the battery managing system and the whole vehicle, and the test and the verification on the functions of overhead protection and the like of the battery. The invention can carry out testing evaluation on the data collection precision of the battery managing system, the evaluation precision of the charge state of the battery and the like.

Electrical circuit componentry is switchable into a defibrillator circuit to deliver a constant pacing current to a patient. The circuitry may include a constant current source inserted in a leg of the defibrillator circuit or a resistor of selected value inserted between a high voltage source and the high side of a defibrillator circuit.

A dimmable, light-emitting diode (LED) power supply adapted to provide a direct current (DC), constant current (“constant current source”) from a conventional, phase-controlled 120 VAC, 60 Hz power source is disclosed. The constant current source of the present invention utilizes two processes to control dimming. In a first process, the phase angle of the input voltage is used to control the duty cycle of a line frequency pulse width modulation (PWM). In a second process, a proportional-current limit adjustment is used to control the average current to the LED during the ON time of the line frequency by PWM. As a result, at relatively low phase angles, peak currents can be lowered, reducing flicker and improving the audible noise levels generated by the circuit.

The method and system described herein is designed to illuminate, control, and network LEDs lights used onboard marine platforms. Disclosed is a method and system for illuminating a portion of a marine vessel or platform. A lighting system is controlled by generating a lighting signal for controlling plurality of LED lights placed in a plurality of positions within the vessel. An LED space is designed to illuminate LEDs (or other lighting fixtures) by providing a controller for providing constant current source via a switching regulator configuration.

The present invention provides a current sensor capable of adjusting an offset value at a zero magnetic field more easily and detecting a current magnetic field generated by a current to be detected with high sensitivity and high precision. The current sensor has: first and second magnetoresistive elements disposed along a conductor so that resistance values change in directions opposite to each other in accordance with a current magnetic field generated by a current to be detected flowing in the conductor; and first and second constant current sources that supply constant currents equal to each other to the first and second magnetoresistive elements, respectively. The current sensor further includes a differential amplifier that detects the difference between voltage drops occurring in the first and second magnetoresistive elements by the constant current. The current to be detected is detected on the basis of the difference between the voltage drops.

In an EL display device which performs area grayscale display, image quality is improved and stabilized. A plurality of subpixels each having light emitting elements which emit light of approximately the same color and a plurality of monitor pixels each having the same number of subpixels as the pixel are provided. The light emitting element in the monitor pixel is manufactured at the same time as the light emitting element in the pixel, and the electrode of the light emitting element in the monitor pixel is connected to a different constant current source in each subpixel. A circuit for changing a potential of the electrode of the light emitting element in the pixel for each subpixel in accordance with a potential change of the electrode of the light emitting element of the monitor pixel, thereby the aforementioned purposes are achieved.

A system and method for providing a constant current source driver for a light emitting diode string. The converter includes a current sensor that derives feedback signal corresponding to a peak current through the light emitting diode string. The feedback signal is used by a controller to vary a duty cycle of the controller to regulate the average current. The controller is operable to regulate the average current as the number of light emitting diodes is increased and/or decreased.

A drive circuit that compensates for the dispersion of the characteristics of drive transistors is disclosed. A switch SW2 is turned off, and switches SW1 and SW3 are turned on. Thereby, a constant current from a constant current source CC1 is flown in a drive transistor T1. Consequently, a gate voltage corresponding to the constant current Is written in the gate of the drive transistor T1. Then, the switches SW1 and SW3 are turned off, and the switch SW2 is turned on. Simultaneously, the voltage of a capacitor C1 on the side of the switch SW4 is varied according to a signal voltage, and thereby the voltage is added to the gate of the drive transistor T1 to flow a current corresponding to the signal voltage in the drive transistor T1.

A phase interpolator circuitry is composed of a delay line, and a phase blender circuit. The delay line delays a first input clock signal to develop a delayed clock signal. The phase blender circuit includes a first inverter receiving the delayed clock signal, and a second inverter receiving a second input clock signal phased away from the first input clock signal. The outputs of the first and second inverters are commonly coupled together. The phase interpolator circuitry additionally includes at least one of constant current sources: first one connected between a power terminal of the first inverter and a power supply, second one connected between a ground terminal of the first inverter and ground, third one connected between a power terminal of the second inverter and a power supply, and fourth one connected between a ground terminal of the second inverter and ground.

An RF amplifier comprises a power amplifier and a dual bias circuit. A dual bias circuit comprises a constant current source and a constant voltage source for biasing the power amplifier. The power may include a heterojunction bipolar transistor (HBT) or a bipolar junction transistor (BJT).

A converter system and method of operating a converter system are disclosed. The converter system comprises a converter power stage that can operate in a Discontinuous Conduction Mode (DCM) in a range of output currents and a Continuous Conduction Mode (CCM) in another range of output currents. The converter power stage includes at least an inductor with an inductor value and a control switch. The converter power stage provides an average current. A current controller is coupled to the converter power stage. When the converter power stage operates in DCM, the converter power stage provides the average current and the current controller is configured to measure the inductor value of the inductor. Furthermore, the current controller can also be configured to measure an input-to-output conversion ratio from the converter power stage.

A method and apparatus for driving LED's is disclosed, comprising the steps of receiving a desired intensity value, wherein the desired intensity value represents the desired intensity for the LED's; generating a first switching control signal, wherein the first switching control signal is a pulse width modulated signal whose duty cycle is based on the desired intensity value; switching the LED's on and off based on the first switching control signal, wherein the switching takes place when the desired intensity value is less than a first desired intensity value threshold; generating a desired constant current value based on the desired intensity value, wherein the desired constant current value represents the value of the desired constant current to drive the LED's; determining an actual constant current value, wherein the actual constant current value represents the value of the actual constant current driving the LED's; comparing the actual constant current value with the desired constant current value; and adjusting the output of the primary drive of the LED's so that the actual constant current value is equal to the desired constant current value. A system for providing LED backlighting of a display is also disclosed, comprising a first constant current source driver, wherein the constant current source driver comprises a primary drive and a step-up circuit; a first series connection of LED's, wherein the LED's are driven by the first constant current driver; and wherein the first constant current source provides a forward voltage of 42 volts or greater to drive the first series connection of LED's.

An LED array switching apparatus comprises, on a single PCB substrate: a plurality of LED arrays D1 to Dn connected in series, each LED array having a forward voltage; an AC voltage supply coupled to the plurality of LED arrays; and a plurality of constant current sources G1 to Gn, coupled to outputs of LED arrays D1 to Dn, respectively, each of the constant current sources being switchable between a current regulating state and an open state such that as the voltage of the AC voltage supply increases, LED arrays are switched on and lit to form a higher forward voltage LED string, and as the voltage of the AC voltage supply decreases, LED arrays are switched off and removed from the LED string starting with the most recently lit LED array.

The invention relates to a constant current output type induction type wireless power transmission converter and a parameter selection method of the constant current output type induction type wireless power transmission converter. The constant current output type induction type wireless power transmission converter and the parameter selection method are suitable for induction type wireless power transmission occasions with fixed air gaps and current type loads. The converter comprises a high-frequency inverter circuit, a primary side compensation capacitor, a loose coupling transformer, an auxiliary side compensation capacitor, a rectification filtering circuit and a load. The resonant frequency of the primary side compensation circuit is equal to that of the auxiliary side compensation circuit, the high-frequency inverter circuit works at the resonant frequency, converter output currents are from a constant current source, the magnitude of the output currents is only relevant to input voltages and the mutual inductance of the loose coupling transformer, input impedance is pure, reactive circulation and device stress are reduced, and efficiency is improved. Converter constant current output characteristics are taken into consideration in the parameter selection method, and on the premise that the distance between the air holes, the size of the transformer and the load are given, mutual inductance, inductance values and coupling coefficients of primary side windings and auxiliary side windings are acquired iteratively with efficiency maximization of the converter as the goal.

The invention belongs to the technical field of electronics, and relates to a street lamp illumination LED driving power supply. The street lamp illumination LED driving power supply consists of a rectification filter circuit, a pre-stage fly-back DC-DC constant voltage source circuit, a post-stage DC-DC constant current source circuit and an intelligent PWM dimming control circuit, wherein the pre-stage fly-back DC-DC constant voltage source circuit consists of a power factor correction (PFC) and PWM control chip NCP1653, a light-coupled isolation detection circuit and an isolation switchingtransformer, and realizes input power factor correction and AC input-to-DC constant voltage output function together with the rectification filter circuit; and the pre-stage DC-DC constant current source circuit is a multi-path constant current output circuit, and each path of constant current output circuit is a Buck-type DC-DC converter with the same structure and realizes conversion from constant voltage to constant current. The intelligent PWM dimming control circuit controls the working state of each path of constant current output circuit through multi-path different control signals to realize intelligent dimming. Compared with the conventional common LED street lamp illumination driving power supply, the street lamp illumination LED driving power supply can save a large amount of peripheral circuits, has the advantages of low cost, small volume, intelligent controllable dimming and the like, and is suitable for batch production.