uba20271 NXP Semiconductors, uba20271 Datasheet - Page 12

• Manufacturer Part Number: uba20271
• Description: 350 V And 600 V Power Ics For Dimmable Compact Fluorescent Lamps
• Manufacturer: NXP Semiconductors

NXP Semiconductors
UBA20271_UBA20272
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 following the start-up state, as soon as the low supply
voltage has reached V
and the voltage on pin CP must pass V
saw-tooth pulses on the CP pin as shown in
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.
CP
and R
Sawtooth, gate driver and half-bridge output signals
ext(RREF)
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V
350 V and 600 V Power ICs for dimmable compact fluorescent lamps
(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
. Additionally the DCI input voltage is higher than V
t
no
9. The circuit consists of a clock generator defined by
th(CP)max
t
dch
Figure
.The preheat time consists of eight
t
no
9. The maximum ignition enabling time
UBA20271/2
001aam766
time (s)
CP
© NXP B.V. 2011. All rights reserved.
is charged to 5 V.
th(start)DCI
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