IRPLLNR4 International Rectifier, IRPLLNR4 Datasheet - Page 9

• Manufacturer Part Number: IRPLLNR4
• Description: BALLAST UNIV INP FLUOR IR2166
• Manufacturer: International Rectifier

Specifications of IRPLLNR4

• Lead Free Status / RoHS Status: Contains lead / RoHS non-compliant
• Other names: *IRPLLNR4

below its rising under-voltage lock-out threshold, it is in its UVLO and also its micro-power mode. The
micro-power mode of the IR2166 allows the use of a large value, low wattage startup resistor
(RSUPPLY). When the voltage on the IR2166 reaches the rising under-voltage lockout threshold
(11.5V), the gate driver oscillator is enabled (this assumes that there are no fault conditions) and
drives the half-bridge output MOSFETs (MHS and MLS). When the half-bridge is oscillating, capaci-
tor CSNUB, diodes DCP1 and DCP2 form a snubber /charge pump circuit which limits the rise and
fall time at the half-bridge output and also supplies the current to charge capacitor CVCC2 to the
VCC clamp voltage (approx. 15.6V) of IR2166. When the rising under-voltage lockout threshold of
the IR2166 is reached, the power factor control oscillator starts to oscillate and drive MOSFET MPFC
to boost and regulate the bus voltage to 400 VDC.
Preheat Mode
When the ballast reaches the end of the UVLO mode, the Preheat mode is entered. At this point the
ballast control oscillator of the IR2166 has begun to operate and the half-bridge output is driving the
resonant load (lamp) circuit.
There is an initial startup
frequency that is much
higher than the steady
state Preheat mode fre-
quency that lasts for only
a short duration. This is
done to ensure that the
initial voltage appearing
across the lamp at the
startup of oscillation does
not exceed the minimum
lamp ignition voltage. If, at
the initiation of oscillation
of the half-bridge, the volt-
age across the lamp is
large enough, a visible
flash of the lamp occurs
which should be avoided.
This in effect is a cold
strike of the lamp, which
Figure 1: Lamp filament current during Preheat and Ignition Ramp (500mA / div)
could shorten the life of
(crossed lamps)
the lamp.
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RD-0602
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