TEA1716T 데이터 시트보기 (PDF) - NXP Semiconductors.
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TEA1716T Datasheet PDF : 35 Pages
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NXP Semiconductors
UBA2071; UBA2071A
Half bridge control IC for CCFL backlighting
ignition
max
fsw
fign
freg
min
0
t
ov
Vsec
0
max
VCVFB
VCIFB
VCSWP
0
VCVFB
VCIFB
t
VCSWP
t
VPWMD
0
t
nom
Ilamp
0 initial
ignition
sweep
PWM-enable delay
steady-state
t
014aaa104
Fig 9. Initial ignition frequency sweep and PWM dimming frequency sweep signals
The lamps start switching again on period GL and GH and the frequency is swept back to
the regulation frequency freg. The duration of the PWM frequency sweep is inverse
proportional to the capacitor connected to the CSWP pin.
8.9 Overvoltage control
The overvoltage control circuit is intended to prevent the transformer output voltage from
exceeding its maximum rating. It can also be used to regulate the output voltage to the
required lamp ignition voltage.
Under normal circumstances the capacitor at the CVFB pin is charged by a constant bias
current Ich(CVFB), thus the voltage on the CVFB pin will increase resulting in a decrease of
switching frequency. If the IC is in current regulation this bias current will flow away via a
tracking circuit which makes the voltage on the CVFB pin following the voltage on the
CIFB pin, see Figure 11.
UBA2071_A_1
Product data sheet
Rev. 01 — 23 June 2008
© NXP B.V. 2008. All rights reserved.
13 of 35
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