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. Capacitor CPH is used to program the frequency sweep time for preheat and ignition of the lamp. If power is restored within one second, the output square-wave duty-cycle is reduced and the dimming level is reduced by one step. The four-level switch-dimming circuit described in this article is only one application where dimming can be achieved without additional wiring. The frequency keeps decreasing until the lamp voltage exceeds the lamp ignition voltage threshold and the lamp ignites.
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As the frequency continues to fall towards the resonance frequency of the tank circuit, the lamp voltage increases until the lamp ignites.
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 lrd designed dimmable electronic ballast systems for a variety of applications.
IRSD IR | Sahin Electronic GmbH
Lrs2530d of four-level switch dimming circuit. 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.
Once the lamp ignites, the lamp current is controlled such that the lamp runs at the desired power and brightness level. The IRSD dimming control IC enables a simple and low-cost solution lfd can be used for a wide variety of dimming applications.
The high-frequency ac square-wave voltage then drives the resonant tank circuit and becomes filtered to produce a sinusoidal current and voltage at the lamp. 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. 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.
Irs25300d 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.
Ped complete reference design Figure 7 shows the through-hole components mounted on the top-side and the surface-mounted components on the bottom side not shown.
The microcontroller IC2 generates a square-wave voltage at pin 5 that is RC-filtered to produce the dc dimming reference ledd at the DIM pin. A microcontroller and pulse detection circuit is used to sense each recycling of irs25530d ac line voltage, change the dimming reference, and store the previous dimming level.
There are many other dimming applications for various end-lighting uses. 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.
How2Power – Answering Your Questions About Power Design
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.
First, the irw2530d line voltage is full-wave rectified with the output of rectifier peak-charging a capacitor to produce a smooth dc bus voltage.
Block diagram of four-level switch-dimming ballast. If the dc reference is decreased, the valley will decrease below COM.
IRS2530DSTRPBF IC DIMMING BALLAST CTRL 8-SOIC IRS2530DSTRPBF 2530 IRS2530 IRS2530D IRS2530DS 2530D
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. The board is a two-layer design with a very small form factor for driving a W fluorescent lamp. 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.
The additional circuit block required for dimming is also shown. The higher the duty cycle, the higher the DIM pin voltage and the higher the brightness level. For further reading on power conversion in lighting applications, see the Jrs2530d Design Guide, and search the Application category and the Lighting subcategory.
If the dimming level was already at minimum then it will cycle back to maximum. Figure 6 shows the microcontroller PWM output for each dimming level and the corresponding waveforms for lamp voltage and current. Block diagram of dimming electronic ballast. 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 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 frequency keeps decreasing until the lamp voltage exceeds the lamp ignition voltage threshold and the lamp ignites. In each case, only the interface circuit needs to be designed such that it generates the correct dc reference voltage to the dimming control IC.
The full application circuit is shown in Figure 5. 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. If the ac line is removed for more than one second, the dimming level will not change.