UBA20270 Просмотр технического описания (PDF) - NXP Semiconductors.
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UBA20270 Datasheet PDF : 32 Pages
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NXP Semiconductors
UBA20270
600 V Driver IC for dimmable compact fluorescent lamps
voltage
(V)
5V
Vth(CP)max 4.5 V
Vth(CP)min 3.8 V
Vth(CB)max 3.6 V
VCB
VCP 1
32
Vth(CB)min 1.1 V
0.6 V
0V
ignition
1
2
61
62
63
boost
transition
burn
time (s)
001aam765
Fig 6. Boost timing
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 CCB and Rext(RREF) a boost time of more than
300 s is possible. In addition to boost bypass at temperature Tj(bp)bst ( 80 C), there is a
temperature protection function during the boost state of Tj(end)bst ( 120 C). If the IC
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 [B].
The current boost in the boost state does not start when Vi(DCI) is lower than Vth(bst)DCI.
Current boost ends when Vi(DCI) is lower than Vth(bst)DCI Vth(bst)hys(DCI) without a boost
transition. See Figure 4 [A].
Remark: If the CB pin is shorted to ground, the boost function is disabled. During such
conditions, the bottom frequency fbridge(min) is 1.8 times higher than the boost bottom
frequency fbridge(bst)min.
7.1.6 Burn state
After the boost state, or when the boost state is bypassed burn state starts. The lamp
current sensor circuit is still enabled. See Figure 4 [A]. The CSI pin (current sense input)
measures the RMS voltage across sense resistor RCSI. It then passes 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 internal reference
level, the lamp current sensor circuit takes over the control of the lamp current. The
UBA20270
Product data sheet
All information provided in this document is subject to legal disclaimers.
Rev. 2 — 8 September 2011
© NXP B.V. 2011. All rights reserved.
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