IRPLLNR4 International Rectifier, IRPLLNR4 Datasheet - Page 18

• 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

The value of REOL4 is changed so that the lamp voltage during normal running produces a signal
with 1.5 Vppk at the point (A) were the capacitor CEOL connects it to the SD pin. For a T5/35W
lamp 1.2Kohm at REOL4 provides the correct voltage.
The SD pin is internally biased at 2V with 1Mohm impedance and therefore at the SD pin a signal
varying between 1.25V and 2.75V will normally be present due to the AC coupling of the 100nF
capacitor (CEOL).
During end of life the lamp voltage may increase either symmetrically (AC end of life, due to a
similar deterioration in both cathode) or asymmetrically (DC end of life, due to a deterioration only
in one cathode). This circuit has the advantage of detecting both failure modes.
The peak to peak voltage at the SD pin will increase (with 2V DC offset) in either case until the
positive peak exceeds 3V and/or the negative peak drops below 1V, therefore triggering the window
comparator shutdown. The threshold of end of life can be adjusted by changing the value of REOL4
(usually 30% Vlamp is required).
Figure 12 shows the voltage in the SD pin and the voltage on the lamp in these 4 cases: no end of
life, DC end of life (upper cathode deteriorated and lower cathode deteriorated) and AC end of life
(both filaments deteriorated in the same way).
www.irf.com
Vspec = VpK in the spec of the lamp
in these 4 cases: no end of life, DC end of life and AC end of life.
Vspec
Figure 12: Voltage in the SD pin and voltage on the lamp
3V
2V
1V
0V
Vspec + 30%
SD pin Voltage
Lamp Voltage
3V
2V
1V
0V
-Vspec - 30%
RD-0602
3V
2V
1V
0V
Vspec + 30%
-Vspec - 30%
3V
2V
1V
0V
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