uba2211 NXP Semiconductors, uba2211 Datasheet - Page 8

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

NXP Semiconductors
UBA2211
Preliminary data sheet
7.10 Minimum glow time control
7.8 Non-overlap time
7.9 OverTemperature Protection (OTP)
Where T
Taking the square root of both sides results in
or
A constant current flows through the power switches and the lamp which is defined by the
internal reference voltage (V
The R
ratio between them is fixed. However by adding a resistor in parallel to C
this ratio can be adjusted. This is described in more detail in the UBA2211 user manual.
The non-overlap time is defined as the time when both MOSFETs are not conducting. The
non-overlap time is fixed internally.
OTP is active in all states. When the die temperature reaches the OTP activation
threshold (T
set to the startup state. When the oscillator is stopped, the DVDT supply no longer
generates the supply current I
state is entered as described in
temperature < T
If the preheat time is set too short or omitted, the lamp electrodes do not have the correct
temperature in the ignition state. This results in instant light but also in a reduced
switching lifetime because when the electrode temperature is too low electrode sputtering
and damage occur. The minimum glow time control minimizes electrode damage by
ensuring maximum power use during the glow phase to heat the electrodes heat as
quickly as possible (see
--------- -
T
RMS V
1
osc
--------- -
T
1
osc
×
SENSE
×
T
SENSE
osc
∫
0
T
osc
osc
∫
0
V
SENSE
V
equals the operating frequency f
th(act)otp
resistor sets both the preheat current and the RMS half-bridge current. The
SENSE
=
All information provided in this document is subject to legal disclaimers.
V
th(rel)otp
2
t ( )DT
O ref
2
(
t ( )DT
), the oscillator is stopped and the power switches (LSPT/HSPT) are
)RMS
=
.
Rev. 2.1 — 7 March 2011
=
Figure
--------- -
T
1
osc
=
O(ref)RMS
--------- -
T
×
R
1
osc
DVDT
T
SENSE
6).
osc
Section 7.2 on page
∫
0
×
V
. Voltage V
T
O ref
osc
∫
0
) and the external R
(
×
V
I
O ref
LSPT
)RMS
(
)RMS
osc
Half-bridge power IC family for CFL lamps
2
DT
DD
Equation
/ 1.
2
gradually decreases and the start-up
DT
5. OTP is reset when the
4:
SENSE
resistor.
UBA2211
© NXP B.V. 2011. All rights reserved.
sw
(see
Figure
8 of 19
(3)
(4)
(5)
7)