UBA2028 NXP Semiconductors, UBA2028 Datasheet - Page 7

• Manufacturer Part Number: UBA2028
• Description: 600 V Dimmable Power Ic For Compact ?uorescent Lamps
• Manufacturer: NXP Semiconductors

NXP Semiconductors
UBA2028_1
Product data sheet
8.10 Capacitive mode protection
8.11 Charge coupling
8.12 Design equations
8.9 Power-down mode
during restart the lamp still fails, the voltage remains high until the end of the ignition time.
At the end of the ignition time the circuit stops oscillating and the circuit will enter the
Power-down mode.
The Power-down mode will be entered if, at the end of the ignition time, the voltage at pin
LVS is above V
TR1 and TR2 will be non-conductive. The V
released from the Power-down mode by lowering the low-voltage supply below V
The signal across R15 see
switching behavior of the half bridge. If, after the preheat state, the voltage across the
ACM resistor (R15 or R6) does not exceed the V
the Capacitive Mode Detection circuit (CMD) assumes that the circuit is in the capacitive
mode of operation. As a consequence the frequency will directly be increased to f
frequency behavior is de coupled from the voltage at pin CSW until C
discharged to zero.
Due to parasitic capacitive coupling to the high voltage circuitry all pins are burdened with
a repetitive charge injection. Given the typical application the pins IREF and CF are
sensitive to this charge injection. For charge coupling of approximately 8 pC, a safe
functional operation of the IC is guaranteed, independent of the current level.
Charge coupling at current levels below 50 A will not interfere with the accuracy of the
V
Charge coupling at current levels below 20 A will not interfere with the accuracy of any
parameter.
The following design equations are used to calculate the desired preheat time, the
maximum ignition time, and the minimum and the maximum switching frequency.
Start of ignition is defined as the moment at which the measured lamp voltage crosses the
V
t
t
f
f
ign
ph
CS
min
max
lamp(fail)
, V
=
=
=
=
1.8
i(PCS)
0.26
40.5 10
2.5
level; see
------------------------- -
330 10
and V
------------------------- -
330 10
f
C
min
lamp(fail)
CT
C
3
CT
i(ACM)
Section
9 –
100 10
--------------------------- -
9 –
. In the Power-down mode the oscillator will be stopped and both
Rev. 01 — 9 October 2009
C
levels.
------------------- -
33 10
CF
R
------------------- -
33 10
IREF
R
8.8.
Figure 8
–
IREF
600 V dimmable power IC for compact fluorescent lamps
12
3
3
33 10
------------------- -
R
IREF
(R6 in
3
Figure
DD
supply is internally clamped. The circuit is
det(capm)
9) also gives information about the
level during the non-overlap time,
CSW
UBA2028
© NXP B.V. 2009. All rights reserved.
has been
DD(rst)
max
7 of 21
. The
.
(1)
(2)
(3)
(4)