IRPLLNR2U International Rectifier, IRPLLNR2U Datasheet - Page 12

• Manufacturer Part Number: IRPLLNR2U
• Description: BALLAST 32W/T8 120V AC IR21571
• Manufacturer: International Rectifier

Specifications of IRPLLNR2U

• Lead Free Status / RoHS Status: Contains lead / RoHS non-compliant
• Other names: *IRPLLNR2U

12
Figure 11 shows the voltage appearing across the lamp while Figure 12 shows the current flowing
through the lamp during Startup, Preheat, Ignition Ramp and Run modes.
where,
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 capacitors CPH, CRAMP, CSTART and CT are 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
Figure 11: Lamp voltage during Startup, Preheat,
Ignition Ramp and Run
V
L
C
P
Lamp
Lamp
= Lamp resonant circuit inductor (L3)
= Lamp resonant circuit capacitor (C14)
= Lamp running power
= Lamp running voltage amplitude
Figure 12: Lamp current during Startup, Preheat,
Ignition Ramp and Run (100mA/div.)
(H)
(F)
(W)
(V)
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