If the dimming level was already at minimum then it will cycle back to maximum. If power is restored within one second, the output square-wave duty-cycle is reduced and the dimming level is reduced by one step. A closed-loop feedback circuit is then used to measure the lamp current and regulate the current to the dimming reference level by continuously adjusting the half-bridge operating frequency. Capacitor CPH is used to program the frequency sweep time for preheat and ignition of the lamp. This simplification of the ballast circuitry allows designers to focus their creativity on developing the different types of dimming interfaces required for each new application. At turn-on, the voltage at the VCO pin will ramp up from 0 V causing the frequency to decrease from the maximum frequency down to the minimum frequency. During pre-ignition, the resonant tank is a series-LC circuit with a high Q-factor.
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The full application circuit is shown in Figure 5. The frequency keeps decreasing until the lamp voltage exceeds the lamp ignition irs25300d threshold and the lamp ignites.
First, the ac line voltage is full-wave rectified with the output of rectifier peak-charging a capacitor to produce a smooth dc bus voltage.
During pre-ignition, the resonant tank is a series-LC circuit with a high Q-factor. Existing interface circuits include a 1-toVdc interface, digitally-addressable lighting interface DALItriac-based wall dimmers, three-way lamp sockets, power line communications, and wireless communications. This simplification of the ballast circuitry allows designers ped focus their creativity on developing the different types of dimming interfaces required for each new application.
The dimming function is realized by combining the ac-lamp-current measurement Figure 3 with the dc reference voltage at a leed node. When the CFL is first turned on, the control IC sweeps the half-bridge irz2530d from the maximum frequency down towards the resonance frequency of the high-Q ballast output stage.
The IRSD dimming control IC includes the feedback control circuit described above, as well as all of the necessary functions to preheat and ignite the lamp and to protect against fault conditions such as open-filament failures, lamp non-strike and mains brown-out.
Block diagram of four-level switch-dimming ballast. If the ac line is removed for more than one second, the dimming level will not change. The feedback circuit will then increase the frequency to decrease the gain of the resonant tank until the valley reaches COM again. The VDD supply capacitor C1 is large enough to allow IC2 to continue to run for more than one second after the ac line has been removed.
Schematic of four-level switch dimming circuit. The lamp arc current is detected through RCS after ignition and coupled onto a dc reference voltage to provide an ac signal with a dc offset at the DIM pin of IC1. Figure 6 shows the microcontroller PWM output for each dimming level and the corresponding waveforms for lamp voltage and current.
A closed-loop feedback circuit is then used to measure the lamp current and regulate the current to the dimming reference level by continuously adjusting the irs2530dd operating frequency. The higher the duty cycle, the higher the DIM pin voltage and the higher the brightness level. The IRSD dimming control IC enables irs5230d simple and low-cost solution that can be used for a wide variety of dimming applications. Once the lamp ignites, the lamp current is controlled such that the lamp runs at the desired power and brightness level.
IRS2530DSTRPBF IC DIMMING BALLAST CTRL 8-SOIC IRS2530DSTRPBF 2530 IRS2530 IRS2530D IRS2530DS 2530D
The four-level switch-dimming circuit described in this article is only one application where dimming can be achieved without additional wiring.
The board is a two-layer design with a very small form factor for driving a W fluorescent lamp. After VDD has discharged below the minimum operating voltage of IC2 the microcontroller will shut off. This article explains how the IRSD operates and presents a complete four-level switch-dimming application circuit built around this IC.
ליאון אלקטרוניקה – REF DESIGN KIT, IRSD ELECTRONIC BALLAST
During DIM mode, the IRSD adjusts the oscillator frequency in order to maintain the amplitude of this feedback signal and control the lamp current for dimming. The lamp filaments are preheated as the frequency decreases and the lamp voltage and load current increase Figure 2.
Lled microcontroller and pulse detection circuit is used to sense each recycling of the ac line voltage, change the dimming reference, and store the previous dimming level. As the frequency continues to fall towards the resonance frequency of the tank circuit, the lamp voltage increases until the lamp ignites.
If the dimming level was already at minimum then it will cycle back to maximum. Prior to that, Tom was e mployed by Knobel Lighting Components in Switzerland where he designed dimmable electronic ballast systems for a irs2530c of applications. After ignition and during the running mode, the tank is a series-L, parallel-RC circuit with a Q-factor somewhere between a high and low value depending on the lamp dimming level.
If power is restored within one second, the output square-wave duty-cycle is reduced and the dimming ped is reduced by one step. This circuitry includes a dimming reference signal, a lamp-current sensing and feedback signal, and a summing circuit for closed-loop control of the lamp current. To fulfill these requirements, the electronic ballast circuit first performs a low-frequency ac-dc conversion at the input, followed by a high-frequency dc-ac conversion at the output.
The lamp arc current begins to flow and a feedback signal is produced at the current-sense resistor RCS. Each of these interface circuits requires additional wiring to each ballast during installation, a special lamp socket or wall dimmer, or an additional signal processing unit. The lamp requires a current to preheat the filaments, a high-voltage signal for ignition, and a high-frequency ac current to maintain operation during the running mode.