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ST7LITE0xxx MICROCONTROLLED BALLAST

3.3 RECTIFYING EFFECT (END OF LIFE)

When the lamp is getting old, it highlights an imbalance between filament depletion. It causes

a non-zero average voltage across the lamp, which can be measured by the voltage sense cir-

cuits depicted in Figure 7. You must determine the maximum allowable level of this offset in

the software. In other words, the circuit in Figure 7 is using the microcontroller as a window

comparator.

As is usual for all abnormal conditions the software will switch to the Stop state to wait for the

lamp change, if this contravention occurs.

3.4 CURRENT OR VOLTAGE EXCEED MAXIMUM VALUES

Exceeding current or voltage maximum (pre-selected in software) in the ballast application

can always mean many different problems, but none of them are good for the ballast itself. So

in the case that the software detects exceeding of maximum values it rather switches to the

Stop state to prevent any damage to the ballast.