UBA2211AP PHILIPS [NXP Semiconductors], UBA2211AP Datasheet - Page 6

• Manufacturer Part Number: UBA2211AP
• Description: Half-bridge power IC family for CFL lamps
• Manufacturer: PHILIPS [NXP Semiconductors]

NXP Semiconductors
UBA2211
Product 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
capacitor on pin SW (C
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 value of the external capacitor (C
capacitor is calculated as shown in
C
I
ph peak
Fig 4.
DD
SW
f

osc nom
is above V
voltage equals V


=
Oscillator, HSPT/LSPT drivers and output signals
Equation

HSPT driver
V
----------------- -
R
LSPT driver
=
half-bridge
ref ph
SENSE
------------------------------------------ -
k
DD(start)

osc
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V
Section
V
OUT

RC

2:
0
0
0
0
R
SW(ph)
osc
1
and OTP is not active. The sweep current (I
SW
Rev. 3 — 26 August 2011
7.2, the IC enters the preheat state when the voltage on pin

). The preheat Operational Transconductance Amplifier (OTA) is
C
; see
ref(ph)
osc
SW(ph)
Figure
). The peak voltage is the voltage at the end of the LSPT
osc(nom)
Equation
SW
so that the peak voltage across R
4.
) sets the preheat time. Typically, the external
and is set at V
Equation
Half-bridge power IC family for CFL lamps
3. The preheat state ends when the falling
1:
SENSE
SW
. An overview of the oscillator,
resistor. The OTA controls the
Figure
SW
) charges the
UBA2211
001aam035
© NXP B.V. 2011. All rights reserved.
SENSE
4.
time (s)
time (s)
time (s)
time (s)
equals the
6 of 20
(1)
(2)