uba2211 NXP Semiconductors, uba2211 Datasheet - Page 6

• Manufacturer Part Number: uba2211
• Description: Half-bridge Power Ic Family For Cfl Lamps
• Manufacturer: NXP Semiconductors

NXP Semiconductors
UBA2211
Preliminary data sheet
7.5 Preheat state
The output voltage of the bridge changes with the falling edge of the signal on pin RC. The
nominal half-bridge frequency is shown in
The maximum frequency is 2.5 × f
internal LSPT and HSPT drive signals and the output is shown in
As described in
V
by the sweep current (I
enabled and the half-bridge circuit starts oscillating.
The preheat current is monitored using the external R
frequency using output voltage V
internal reference voltage (V
conduction time. The preheat peak current through the lamp filament is calculated as
shown in
The preheat time is set by the external capacitor (C
down-going C
If during the preheat time, capacitive mode is sensed, the internal V
discharged and the frequency sweep restarts at f
I
ph peak
Fig 4.
DD
f
(
osc nom
is above V
(
)
=
Oscillator, HSPT/LSPT drivers and output signals
Equation
)
HSPT driver
V
----------------- -
R
LSPT driver
=
half-bridge
ref ph
SENSE
SW
------------------------------------------ -
k
DD(start)
(
osc
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V
Section
V
OUT
voltage equals V
)
RC
×
2:
0
0
0
0
R
osc
1
and OTP is not active. The capacitor on pin SW (C
SW
Rev. 2.1 — 7 March 2011
7.2, the IC enters the preheat state when the voltage on pin
×
). The preheat Operational Transconductance Amplifier (OTA) is
C
ref(ph)
osc
SW(ph)
). The peak voltage is the voltage at the end of the LSPT
SW(ph)
osc(nom)
so that the peak voltage across R
; see
and is set at V
Equation
Half-bridge power IC family for CFL lamps
Figure
max
SW
1:
.
4.
SENSE
). The preheat state ends when the
SW
. An overview of the oscillator,
resistor. The OTA controls the
Figure
SW
UBA2211
001aam035
HIGH node is
© NXP B.V. 2011. All rights reserved.
SENSE
4.
time (s)
time (s)
time (s)
time (s)
SW
) is charged
equals the
6 of 19
(1)
(2)