uba20271 NXP Semiconductors, uba20271 Datasheet - Page 9

• Manufacturer Part Number: uba20271
• Description: 350 V And 600 V Power Ics For Dimmable Compact Fluorescent Lamps
• Manufacturer: NXP Semiconductors

NXP Semiconductors
UBA20271_UBA20272
Product data sheet
7.1.6 Burn state
In the boost state, the lamp current feedback control circuit operates the same as in the
burn state. This action is used to improve lamp stability. Lamp current boosted by a fixed
ratio of 1.5 compared to the burn state, boosts up the slow luminescence increase of a
cold CFL lamp. In the boost to burn transition time there is a slow 15-step ratio decrease
from 1.5 to 1. For the transition to burn time, the preheat timer is reused and the boost
ratio is gradually decreased in 15 steps from 1.5 to 1. The steps occur within 32
saw-toothed pulses on the CP pin. The 32 saw-toothed pulses form the transition time
from boost to burn to enable a smooth transition between the current controlled boost and
burn state. Given the application values of C
300 s is possible. In addition to boost bypass at temperature T
temperature protection function during the boost state of T
temperature passes this level during boost, the transition timer is immediately started in
order to enter the burn state faster. This action effectively reduces the boost time. See
Figure 4
The current boost in the boost state does not start when V
Current boost ends when V
transition. See
Remark: If the CB pin is shorted to ground, the boost function is disabled. During such
conditions, the bottom frequency f
frequency f
After the boost state, or when the boost state is bypassed burn state starts. The lamp
current sensor circuit is still enabled. See
measures the RMS voltage across sense resistor R
Double-Sided Rectifier (DSR) circuit and fed towards an Operational Transconductor
Amplifier (OTA). When the RMS voltage on the CSI pin reaches the internal reference
level, the lamp current sensor circuit takes over the control of the lamp current. The
Fig 6.
V
V
V
V
th(CP)max
th(CB)max
th(CP)min
th(CB)min
0.6 V
5 V
0 V
voltage
[B].
Boost timing
(V)
bridge(bst)min.
4.5 V
3.8 V
3.6 V
1.1 V
ignition
Figure 4
All information provided in this document is subject to legal disclaimers.
350 V and 600 V Power ICs for dimmable compact fluorescent lamps
V
CB
Rev. 2 — 8 September 2011
[A].
1
i(DCI)
is lower than V
bridge(min)
2
boost
Figure 4
is 1.8 times higher than the boost bottom
CB
61
and R
th(bst)DCI
[A]. The CSI pin (current sense input)
CSI
ext(RREF)
. It then passes through a
62
 V
i(DCI)
j(end)bst
th(bst)hys(DCI)
V
CP
a boost time of more than
j(bp)bst
is lower than V
UBA20271/2
63
( 120 C). If the IC
1
( 80 C), there is a
transition
© NXP B.V. 2011. All rights reserved.
without a boost
th(bst)DCI
001aam765
time (s)
32
burn
9 of 33
.