IRPLDIM1U Ver la hoja de datos (PDF) - International Rectifier
Número de pieza
componentes Descripción
Fabricante
IRPLDIM1U Datasheet PDF : 12 Pages
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Waveforms
Figure 4 shows the voltage appearing across the lamp while Figure 5 shows the current flowing
through the lamp during Startup, Preheat, Ignition and Dim modes.
Figure 4, Lamp voltage during Startup, Preheat,
Ignition and Dim (100%)
Figure 5, Lamp current during Startup, Preheat,
Ignition and Dim (100%) (100mA/div.)
Normal Powerdown
A Normal Powerdown occurs when the AC line voltage is disconnected from the ballast. When this
occurs the voltage on the VDC pin of IC2 drops below the line fault threshold (3V) and IC2 shuts
down in a controlled fashion. The oscillator is stopped, the half-bridge driver outputs (LO and HO)
are turned off and capacitor CPH is discharged. IC2 also goes into its UVLO/micro-power mode and
the bus voltage begins to collapse.
Fault Mode
Fault mode is when the ballast driver is shutdown due to the detection of a lamp fault. Note that when
the ballast is in this Fault mode the power factor correction section of the ballast is also shutdown
and the bus voltage will drop to the non-boosted/unregulated level. There are several lamp fault
conditions which can put the ballast into the Fault mode. The lamp fault conditions detected include:
near/below resonance (under-current) detection, hard-switching detection and over-current detec-
tion. Resistor RCS in the source lead of the low side MOSFET (M3) serves as the current sensing
point for the half-bridge which is used to detect these lamp fault conditions. In operation when the
half-bridge is oscillating, a voltage appears across RCS whenever the low side MOSFET, M3, is
turned on or the high side MOSFET, M2, is turned off. The magnitude of this voltage directly relates
to the current in the lamp resonant circuit. Figure 6 shows the voltage which appears across resistor
RCS during normal Run mode conditions while Figure 14 shows the voltage appearing across the
lamp during the end of Preheat mode, Ignition Ramp mode and the beginning of Run mode. Also
shown in Figure 7 are the gate drive signals for the low side MOSFET (LO pin) and the high side
MOSFET (HO-VS pin).
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