uba20261 NXP Semiconductors, uba20261 Datasheet - Page 9

• Manufacturer Part Number: uba20261
• Description: 600 V And 350 V Power Ic For Step Dimmable Cfls
• Manufacturer: NXP Semiconductors

NXP Semiconductors
UBA20261_UBA20262
Preliminary data sheet
7.1.6 Burn state
In the boost state, a lamp current feedback control is implemented to improve lamp
stability (see
burn state to boost 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 down to 1. The
preheat timer is reused for the transition to burn time and the boost ratio is gradually
decreased in 15 steps from 1.5 to 1, within 32 saw-tooth pulses on the CP pin. Using the
application values for C
addition to boost bypass at a temperature of T
function is implemented during boost state of T
passes this level during boost, the transition timer is immediately started to enter the burn
state faster. Effectively this reduces the boost time (see
The boost state current boost does not start in dim modes DIM_2, DIM_3 or MDL
(see
Remark: If the CB pin is short circuited to ground, the boost function is disabled. In such a
situation, the bottom frequency f
frequency f
After the boost state or when it is bypassed, the burn state starts. The lamp current sensor
circuit remains enabled (see
measured by the CSI (Current Sense Input) pin. It is then passed through a Double-Sided
Rectifier (DSR) circuit and fed towards an Operational Transconductor Amplifier (OTA).
When the RMS voltage on the CSI pin reaches the actual internal reference level, the
lamp current sensor circuit takes over control of the lamp current. The internal current
output of the OTA is transferred using an integrator on the CI pin to the input for Voltage
Controlled Oscillator (VCO). The VCO regulates the frequency and as a result, the lamp
current.
Fig 6.
V
V
V
V
th(CP)max
th(CB)max
th(CP)min
th(CB)min
Figure 4
0.6 V
5 V
0 V
voltage
Boost timing
(V)
bridge(bst)min
4.5 V
3.8 V
3.6 V
1.1 V
ignition
Section
[A]).
All information provided in this document is subject to legal disclaimers.
V
CB
7.1.6). The lamp current has a fixed ratio of 1.5 compared to the
Rev. 1 — 9 September 2011
.
CB
and R
1
Figure
bridge(min)
ext(RREF),
600 V and 350 V power IC for step dimmable CFLs
4[A]). The voltage across sense resistor R
2
boost
is 1.8 times higher than the boost bottom
a boost time of more than 300 s is possible. In
61
j(bp)bst
j(end)bst
( 80 C), a temperature protection
( 120 C). If the temperature
62
Figure 4
V
CP
UBA20261/2
63
[B]).
1
transition
© NXP B.V. 2011. All rights reserved.
CSI
001aam765
, is
time (s)
32
burn
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