A complete set of schematics and waveforms is included to help designers better understand and design the new circuit. If the dc reference is decreased, the valley will decrease below COM. 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. The higher the duty cycle, the higher the DIM pin voltage and the higher the brightness level. 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.
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For further reading on power conversion in lighting applications, see the How2Power Design Guide, and search the Application category and the Lighting subcategory.
IRS2530DSTRPBF IC DIMMING BALLAST CTRL 8-SOIC IRS2530DSTRPBF 2530 IRS2530 IRS2530D IRS2530DS 2530D
There are many other dimming applications for various end-lighting uses. In each case, only the interface circuit needs to be designed such that it generates the correct dc reference voltage to the dimming control Irs25330d.
The four-level switch-dimming circuit described in this article is only one application where dimming can be achieved without additional wiring. After VDD has discharged below the minimum operating voltage of IC2 the microcontroller will shut off. Block diagram of dimming electronic ballast. Schematic of four-level switch dimming circuit.
IRSD IR | Sahin Electronic GmbH
If the ac line is removed for more than one second, the dimming level will not change. If the dimming lee was already at minimum then it will cycle back to maximum. 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. Prior to that, Tom was e mployed by Knobel Lighting Components in Switzerland where he designed dimmable igs2530d ballast systems for a variety of applications.
Figure 6 shows the microcontroller PWM output for each dimming level and the corresponding waveforms for lamp voltage and current.
The board is a two-layer design with a very small form factor for driving a W fluorescent lamp. Electronic ballasts for dimming fluorescent lamps require a control interface for the user to set the desired lamp-brightness level.
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.
To dim the fluorescent lamp, the frequency of the half-bridge is increased, causing the gain of the resonant tank circuit to decrease and therefore the lamp current to decrease. 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.
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. The complete reference design Figure 7 shows the through-hole components mounted ids2530d the top-side and the surface-mounted components on the bottom side not shown.
If power is restored within one second, the output square-wave duty-cycle is reduced ids2530d the dimming level is irs2503d by one step. This causes the amplitude of the lamp current to then increase or decrease for dimming. 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. The lamp arc current begins to flow and a feedback signal is produced at the current-sense resistor RCS.
This article explains how the Eld operates and presents a complete four-level switch-dimming application circuit built around this IC. The frequency keeps decreasing until the lamp voltage exceeds the lamp ignition voltage threshold and the lamp ignites. The additional circuit block required for dimming is also shown. During pre-ignition, the resonant tank is a series-LC circuit with a high Q-factor. 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.
Once the lamp ignites, the leed current is controlled such that the lamp runs at the desired power and brightness level. As the frequency continues to fall towards the resonance frequency of the tank circuit, the lamp voltage increases until the lamp ignites. IRSD Operation 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.
The dimming function is realized by combining lev ac-lamp-current measurement Figure 3 with the dc reference voltage at a single node. When the CFL is first turned on, the control IC sweeps the half-bridge frequency from the maximum frequency down towards the resonance frequency of the high-Q ballast output stage.
If the dc reference is decreased, the valley will decrease below COM.
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.