uba20261 NXP Semiconductors, uba20261 Datasheet - Page 7

• 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
7.1.4 Ignition state
New preheat cycles start after the CP pin level slowly discharges until V
recharges above V
After the preheat state has been completed, the ignition state is entered. In the ignition
state, the frequency sweeps down on the CI pin due to capacitor C
current as shown in
approaches the resonant frequency of the resonant tank (L2, C5). This action causes a
high voltage across the lamp to ignite the lamp. The ignition current sensor circuit which
monitors the voltage over resistor R
If the voltage on pin CSI is above the typical ignition detection threshold voltage level of
0.6 V, lamp ignition is detected. The system changes from ignition state to either the boost
or burn state.
If ignition not is detected, the frequency drops further to the minimum half-bridge
frequency f
application due to lamp damage, the IC only tries to ignite the lamp twice after power-up.
The ignition attempt counter increments at the end of the ignition enabling time when the
lamp ignition threshold voltage on the CSI pin is not exceeded. The ignition enabling time
is typically
time-out period, the IC enters the power-down state (see
Fig 4.
(kHz)
100
f
CFL frequency from start to burn state
preheat frequency
1
bridge(min)
⁄
4
preheat
start frequency
of the preheat time t
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th(CP)max
Figure
frequency. To avoid repeated ignition attempts and overheating of the
Rev. 1 — 9 September 2011
ignition
CFL ignition
4. During this continuous decrease in frequency, the circuit
provided V
boost bottom ~22 kHz
ph
600 V and 350 V power IC for step dimmable CFLs
CSI
. If a second ignition attempt also exceeds the ignition
A
DD
(see
> V
B
Figure
DD(start)
boost
12) detects lamp ignition.
C
(see
Figure
Figure
UBA20261/2
transition
5).
5).
CI
charging at a fixed
© NXP B.V. 2011. All rights reserved.
CP
burn
< V
th(rel)CP
001aam764
100 %
time (s)
7 of 32
and