Datasheet

UBA20260 All information provided in this document is subject to legal disclaimers. © NXP B.V. 2011. All rights reserved.
Product data sheet Rev. 2 — 10 October 2011 13 of 30
NXP Semiconductors
UBA20260
600 V driver IC for step dimmable CFLs
Four internal references determine the actual internal set point levels used for the different
step dim levels. Depending on the selected dim level, the current control feedback loop
regulates the voltage on the CSI pin. In this way, it ensures that V
i(CSI)
is equal to one of
the selected internal set point voltages. The sequence of the four dim steps shown in
Figure 11
is as follows:
• The lamp is switched off longer than the memory retention time: the IC starts up in the
DIM_1 mode (lamp is 100 % on, no dimming)
• After lamp off/on toggling, the IC twice enters the DIM_2 mode: the lamp is dimmed to
approximately 66 %
(1)
of its initial light output
• The next lamp off/on toggling, the IC enters the DIM_3 mode: the lamp is dimmed
approximately 33 %
(1)
of its initial light output
• Toggling the lamp off/on again: the IC enters the MDL (Minimum Dimming Level)
mode. This level equals approximately 10 %
(1)
of the initial light output
• Renewed toggling enters the DIM_1 mode again.
Where
(1)
= R
MDL
= 2 k
Fig 10. Supply voltage cycle for dim step change
0
V
DD(rst)
V
ret(dim)CP
V
DD(stop)
V
DD(start)
5
lamp on
old dim level
lamp on
new dim level
dim step
change
lamp off
V
DD
V
CP
voltage
(V)
time (s)
001aam769
start-upretention