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RD-0613

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Fig. 10: CPH Pin Voltage (Black) and Lamp Voltage (Blue) During Lamp

Non-Strike Fault Condition

During Ignition Mode, the voltage on the CPH pin of the IRS2168D continues to ramp up until the

fault counter is disabled during Ignition Mode due to the ignition regulation feature and enabled again

at the start of Run Mode. During a lamp non-strike condition, the ignition voltage will be regulated for

the duration of Ignition Mode and then unregulated during Run Mode. This means that the ignition

voltage will increase slightly after Ignition Mode (as the frequency decreases towards the run

frequency) until the fault counter times out, after 65 cycles above the over-current threshold, and the

ballast shuts off. The amount of frequency shift and resulting voltage increase is determined by the

value of CVCO. The 5 V shutdown threshold at the SD pin is also disabled during Ignition Mode and

enabled again at the start of Run Mode. A full explanation of the functionality of the over-current

sensing and shutdown functions are in the Fault Mode section.

Run Mode

During Run Mode and after a successful lamp ignition, the frequency is at the final run frequency and

is determined by RFMIN. The 1 V and 3 V end-of-life (EOL) window comparator at the SD/EOL pin,

the 5 V unlatched shutdown threshold at the SD/EOL pin, and the fault counter at the CS pin, are all

enabled in Run Mode. A functional description of the over-current sensing and end-of-life sensing is

given in the Fault Mode section.