IRPLLNR2U International Rectifier, IRPLLNR2U Datasheet - Page 9

• 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

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Figure 6 shows a plot of the half-bridge oscillation frequency as a function of time for all of the normal
modes of operation: Preheat mode, Ignition Ramp mode and Run mode. As shown in Figure 6 there
is an initial startup frequency that is much higher than the steady state Preheat mode frequency that
lasts for only a short duration. Components CSTART and RSTART are used to program this initial
startup frequency. This is done to insure 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 oscil-
lation of the half-bridge, the voltage 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 could shorten the life
of the lamp. An oscillograph of the lamp voltage at startup is shown in Figures 7 and 8 (next page).
Figure 7 shows the lamp voltage without the high initial startup frequency while Figure 8 shows the
lamp voltage with the high initial frequency startup.
Figure 4: Lamp filament current during Startup,
Preheat, Ignition Ramp and Run (500mA/div)
f
f
f
Preheat
Run
Ignition
f
osc
Figure 6: Oscillator frequency versus time, Normal operating conditions
preheat
ignition
Figure 5: Lamp filament voltage during Startup,
Preheat, Ignition Ramp and Run
run
t
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