Datasheet

8
UCC2305
UCC3305
time constants are external film capacitors CS and CW,
and are connected to SLOPEC and WARMUPC. CS and
CW are critical capacitors and must be selected to
match the time-temperature relationship of the lamp.
In addition to changing the power regulation point, the
WARMUPC capacitor voltage also changes the short cir
-
cuit lamp current. The ratio of cold short circuit current to
warmed-up short circuit current is set by the resistor
from ADJ to ground.
When power is removed from the ballast, CS and CW
must discharge at a controlled rate. The discharge cur
-
rents are programmed by current sources on the
UCC3305 HID Controller. These current sources are
powered by the power supply connected to BYPASS. In
a typical application, a non-critical electrolytic capacitor
from BYPASS to ground stores energy when the ballast
is on and uses this energy to control the discharge rate
when the ballast is off.
FLYBACK HID BALLAST
UDG-94092-1
APPLICATIONS INFORMATION (cont.)