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 22 of 30
NXP Semiconductors
UBA20260
600 V driver IC for step dimmable CFLs
11. Application information
11.1 Design equations
All described equations are only valid for R
ext(RREF)
= 33 k.
11.1.1 C
CP
related timing equations
• Preheat time
(1)
• Ignition enabling time
(2)
• Overcurrent fault time
(3)
• Transition to burn time
(4)
• Retain time step dimming
(5)
• Restart delay time
(6)
Where I
restart(CP)
=0.5A (typical).
11.1.2 C
CB
related timing equation
• Boost time
(7)
t
ph
C
CP
I
oCP
--------------
16 V
hys CP
5V
th CPmax
–+=
t
en ign
C
CP
I
oCP
--------------
4V
hys CP
=
t
fault oc
C
CP
I
oCP
--------------
5V
th CPmin
–=
t
t bst burn–
C
CP
I
oCP
--------------
64 V
hys CP
5V
th CPmax
–+=
t
ret dim
C
CP
I
ret dimCP
-------------------------
5V
ret dimCP
–=
t
drestart
C
CP
V
th CPmax
V
th relCP
–
I
restart CP
-------------------------------------------------------------
=
t
bst
C
CB
I
oCB
--------------
126 V
hys CB
V
th CBmin
0.6–+=