UBA2211AP PHILIPS [NXP Semiconductors], UBA2211AP Datasheet - Page 8

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

NXP Semiconductors
UBA2211
Product data sheet
7.10 Minimum glow time control
7.8 Non-overlap time
7.9 OverTemperature Protection (OTP)
During the other oscillator clock cycle, the input of the squarer is connected to the internal
reference voltage V
current. This charge current is also added to capacitor C
equal, then
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. The ratio adjustment is described in more detail in UM10418,
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 and is fixed at the t
OTP is active in all states. When the die temperature reaches the OTP activation
threshold (T
set to the start-up 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 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
Equation 4
equals the operating frequency f
th(act)otp
resistor sets both the preheat current and the RMS half-bridge current. The
SENSE
=
Figure
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V
th(rel)otp
2
t  DT
O ref
2

t  DT
), the oscillator is stopped and the power switches (LSPT/HSPT) are
O(ref)RMS
6).
RMS
=
Rev. 3 — 26 August 2011
.
is true:
=
--------- -
T
1
osc
=
. This voltage is squared and converted into a negative
O(ref)RMS
--------- -
T

R
1
osc
DVDT
T
SENSE
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
no
5:
SW
value (see
SENSE
. When both currents are
resistor.
Table
UBA2211
© NXP B.V. 2011. All rights reserved.
sw
5).
(see
Figure
8 of 20
(4)
(5)
(6)
7)