UBA20262 データシートの表示（PDF） - NXP Semiconductors.
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UBA20262 Datasheet PDF : 32 Pages
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NXP Semiconductors
UBA20261/2
600 V and 350 V power IC for step dimmable CFLs
New preheat cycles start after the CP pin level slowly discharges until VCP < Vth(rel)CP and
recharges above Vth(CP)max provided VDD > VDD(start) (see Figure 5).
f
(kHz)
100
start frequency
CFL ignition
A
B
C
preheat frequency
boost bottom ~22 kHz
100 %
time (s)
preheat
ignition
boost
Fig 4. CFL frequency from start to burn state
transition
burn
001aam764
7.1.4 Ignition state
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 CCI charging at a fixed
current as shown in Figure 4. During this continuous decrease in frequency, the circuit
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 RCSI (see Figure 12) detects lamp ignition.
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 fbridge(min) frequency. To avoid repeated ignition attempts and overheating of the
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 1⁄4 of the preheat time tph. If a second ignition attempt also exceeds the ignition
time-out period, the IC enters the power-down state (see Figure 5).
UBA20261_UBA20262
Product data sheet
All information provided in this document is subject to legal disclaimers.
Rev. 2 — 10 October 2011
© NXP B.V. 2011. All rights reserved.
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