Datasheet

L6585DE Ballast section
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edge blanking is active during this time in order to avoid any detection of hard switching
events, very common during this phase.
3. Ignition: At the end of the TCH cycle, the EOI pin is left free in high impedance mode.
Therefore, the capacitor connected between EOI and ground is charged by RF through
R
PRE
. The current sunk from the RF pin decreases exponentially, and the frequency
along with it. An exponential decrease in switching frequency causes a linear increase
of the lamp voltage. When the lamp voltage reaches the strike value, the lamp ignites.
Ignition time is set by the value of
R
PRE
and C
IGN
.
During ignition current control protection, anti-ballast choke saturation protection and
leading edge blanking are all active.
Figure 8. Half-bridge protection thresholds during ignition
4. Run mode: When the EOI voltage reaches 1.9 V, the IC enters run mode and the
switching frequency is set only by R
RUN
. Current control protection and anti-ballast
choke saturation are now active with a lower threshold, leading edge blanking is not
active and a fast hard switching detector is activated.
Figure 9. Half-bridge protection thresholds during run mode