uba20270 NXP Semiconductors, uba20270 Datasheet - Page 12

• Manufacturer Part Number: uba20270
• Description: 600 V Driver Ic For Dimmable Compact Fluorescent Lamps
• Manufacturer: NXP Semiconductors

NXP Semiconductors
UBA20270
Product data sheet
7.2.2 Combined timing circuit
A combined timing circuit is included to determine the preheat time, ignition enabling time
and overcurrent time, see
C
The timing circuit starts operating after the start-up state, as soon as the low supply
voltage has reached V
V
of eight saw-tooth pulses on the CP pin as shown in
enabling time following the preheat phase is two complete sawtooth (triangular) pulses.
During the boost and burn state, part of the timer is used to generate the maximum
overcurrent time (more than one half of the saw-toothed pulse). If a continuous
overcurrent is detected, the timer starts.
Fig 8.
th(start)DCI
CP
and R
Sawtooth, gate driver and half-bridge output signals
ext(RREF)
and the voltage on the CP pin must pass V
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V
(GHS-HBO)
and a counter. When the timer is not operating, C
V
V
HBO
V
GLS
Rev. 2 — 8 September 2011
CF
DD(start).
voltage
0
0
0
0
(V)
Figure
600 V Driver IC for dimmable compact fluorescent lamps
Additionally the DCI input voltage must be higher than
t
no
9. The circuit consists of a clock generator defined by
t
dch
t
no
Figure
th(CP)max
9. The maximum ignition
. The preheat time consists
001aam766
UBA20270
time (s)
CP
© NXP B.V. 2011. All rights reserved.
is charged to 5 V.
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