UBA2021
630 V driver IC for CFL and TL lamps
Rev. 04 — 25 July 2008
Product data sheet
1. General description
The UBA2021 is a high voltage IC intended to drive and control Compact Fluorescent
Lamps (CFL) or fluorescent TL lamps. It contains a driver circuit for an external
half-bridge, an oscillator and a control circuit for starting up, preheating, ignition, lamp
burning and protection.
2. Features
I
I
I
I
I
I
I
I
Adjustable preheat and ignition time.
Adjustable preheat current.
Adjustable lamp power.
Lamp power independent from mains voltage variations.
Overpower protection.
Lamp temperature stress protection at higher mains voltages.
Capacitive mode protection.
Protection against a drive voltage that is too low for the power MOSFETs.
3. Quick reference data
Table 1.
Symbol
V
FS
V
VS(start)
V
VS(stop)
I
VS(standby)
f
start
t
ph
V
RS(ctrl)
f
B
t
ign
f
B
t
no
Quick reference data
Parameter
high side supply voltage
oscillator start voltage
oscillator stop voltage
standby current
start frequency
preheat time
control voltage at pin RS
bottom frequency
ignition time
bottom frequency
non-overlap time
C
CP
= 100 nF
V
VS
= 11 V
Conditions
I
FS
< 15
µA;
t < 0.5 s
Min
-
-
-
-
-
-
-
-
-
-
-
Typ
-
11.95
10.15
200
108
666
−600
42.9
625
42.9
1.4
Max
630
-
-
-
-
-
-
-
-
-
-
Unit
V
V
V
µA
kHz
ms
mV
kHz
ms
kHz
µs
High voltage supply
Start-up state
Preheat mode
Frequency sweep to ignition
Normal operation
NXP Semiconductors
UBA2021
630 V driver IC for CFL and TL lamps
Quick reference data
Parameter
total supply current
high and low side on
resistance
high and low side off
resistance
feed-forward frequency
operating range of input
current at pin RHV
I
RHV
= 0.75 mA
I
RHV
= 1.0 mA
Conditions
f
B
= 43 kHz
Min
-
-
-
Typ
1
126
75
Max
-
-
-
Unit
mA
Ω
Ω
Table 1.
Symbol
I
tot
R
G1(on)
,
R
G2(on)
R
G1(off)
,
R
G2(off)
Feed-forward
f
ff
I
i(RHV)
-
-
0
63.6
84.5
-
-
-
kHz
kHz
1000
µA
4. Ordering information
Table 2.
Ordering information
Package
Name
UBA2021T
UBA2021P
SO14
DIP14
Description
plastic small outline package; 14 leads; body width 3.9 mm
plastic dual in-line package; 14 leads (300 mil)
Version
SOT108-1
SOT27-1
Type number
5. Block diagram
VS
5
RHV
13
RREF CF
10
12
CI
14
bootstrap
charging circuit
SB
SUPPLY
n.c.
4
BAND GAP
REFERENCE
8
NON
OVERLAP
OSCILLATOR
LEVEL
SHIFTER
HIGH SIDE
DRIVER
1
2
3
FS
G1
S1
CP
TIMING
LOW SIDE
DRIVER
6
G2
RS
9
RS
MONITOR
CONTROL
7
UBA2021
11
SGND
PGND
mgs988
Fig 1.
Block diagram
UBA2021_4
© NXP B.V. 2008. All rights reserved.
Product data sheet
Rev. 04 — 25 July 2008
2 of 16
NXP Semiconductors
UBA2021
630 V driver IC for CFL and TL lamps
6. Pinning information
6.1 Pinning
FS
G1
S1
n.c.
VS
G2
PGND
1
2
3
4
5
6
7
001aai566
14 CI
13 RHV
12 CF
FS
G1
S1
n.c.
VS
G2
PGND
1
2
3
4
5
6
7
001aai567
14 CI
13 RHV
12 CF
UBA2021T
11 SGND
10 RREF
9
8
RS
CP
UBA2021P
11 SGND
10 RREF
9
8
RS
CP
Fig 2.
Pin configuration (SO14)
Fig 3.
Pin configuration (DIP14)
6.2 Pin description
Table 3.
Symbol
FS
G1
S1
n.c.
VS
G2
PGND
CP
RS
RREF
SGND
CF
RHV
CI
Pin description
Pin
1
2
3
4
5
6
7
8
9
10
11
12
13
14
Description
high side floating supply voltage
gate high transistor (T1)
source high transistor (T1)
high-voltage spacer, not to be connected
low voltage supply
gate low transistor (T2)
power ground
timing/averaging capacitor
current monitoring input
reference resistor
signal ground
oscillator capacitor
start-up resistor/feed-forward resistor
integrating capacitor
7. Functional description
7.1 Introduction
The UBA2021 is an integrated circuit for electronically ballasted compact fluorescent
lamps and their derivatives operating with mains voltages up to 240 V (RMS). It provides
all the necessary functions for preheat, ignition and on-state operation of the lamp. In
addition to the control function, the IC provides level shift and drive functions for the two
discrete power MOSFETs, T1 and T2 (see
Figure 7).
UBA2021_4
© NXP B.V. 2008. All rights reserved.
Product data sheet
Rev. 04 — 25 July 2008
3 of 16
NXP Semiconductors
UBA2021
630 V driver IC for CFL and TL lamps
7.2 Initial start-up
Initial start-up is achieved by charging capacitor CS9 with the current applied to the
RHV-pin. At start-up, MOSFET T2 conducts and T1 does not conduct. This ensures C
boot
becomes charged. This start-up state is reached for a supply voltage of V
VS(reset)
. This is
the voltage level on the VS-pin at which the circuit will be reset to its initial state and
maintained until the low voltage supply (V
VS
) reaches a value of V
VS(start)
. The circuit is
reset to the start-up state.
7.3 Oscillation
When the low voltage supply (V
VS
) has reached the value of V
VS(start)
the circuit starts
oscillating in the preheat state. The internal oscillator is a current-controlled circuit which
generates a sawtooth waveform. The frequency of the sawtooth is determined by the
capacitor C
CF
and the current out of the CF-pin, mainly set by R
RREF
. The sawtooth
frequency is twice the frequency of the signal across the load. The IC brings MOSFETs
T1 and T2 alternately into conduction with a duty factor of approximately 50 %.
Figure 4
represents the timing of the IC. The circuit block 'non-overlap' generates a non-overlap
time t
no
that ensures conduction periods of exclusively T1 or T2. Time t
no
is dependent on
the reference current I
RREF
.
start-up
V
CF
0
internal
clock
0
V
(G1-S1)
0
V
(G2)
0
time
mgs991
t
no
t
no
Fig 4.
Oscillator timing
7.4 Operation in the preheat mode
The circuit starts oscillating at approximately 2.5
×
f
B
(108 kHz). The frequency gradually
decreases until a defined value of current I
shunt
is reached (see
Figure 5).
The slope of the
decrease in frequency is determined by capacitor C
CI
. The frequency during preheating is
approximately 90 kHz. This frequency is well above the resonant frequency of the load,
which means that the lamp is off, the load only consists of L2, C5 and the electrode
resistance. The preheat time is determined by capacitor C
CP
. The circuit can be locked in
the preheat state by connecting the CP-pin to ground. During preheating, the circuit
monitors the load current by measuring the voltage drop over external resistor R
shunt
at
the end of
conduction of T2 with decision level V
RS(ctrl)
. The frequency is decreased as long as
V
RS
> V
RS(ctrl)
. The frequency is increased for V
RS
< V
RS(ctrl)
.
UBA2021_4
© NXP B.V. 2008. All rights reserved.
Product data sheet
Rev. 04 — 25 July 2008
4 of 16
NXP Semiconductors
UBA2021
630 V driver IC for CFL and TL lamps
f
start
f
B
preheat state
ignition
state
burn state
time
mgs992
Fig 5.
Operation in the preheat mode
7.5 Ignition state
The RS monitoring function changes from V
RS(ctrl)
regulation to capacitive mode
protection at the end of the preheat time. Normally this results in a further frequency
decrease down to the bottom frequency f
B
(approximately 43 kHz). The rate of change of
frequency in the ignition state is less than that in the preheat mode. During the downward
frequency sweep the circuit sweeps through the resonant frequency of the load. A high
voltage then appears across the lamp. This voltage normally ignites the lamp.
7.6 Failure to ignite
Excessive current levels may occur if the lamp fails to ignite. The IC does not limit these
currents in any way.
7.7 Transition to the burn state
Assuming that the lamp has ignited during the downward frequency sweep, the frequency
normally decreases to the bottom frequency. The IC can transit to the burn state in two
ways:
1. In the event that the bottom frequency is not reached, transition is made after
reaching the ignition time t
ign
.
2. As soon as the bottom frequency is reached.
The bottom frequency is determined by R
RREF
and C
CF
.
7.8 Feed-forward frequency
During burn state a feed-forward mechanism ensures that the lamp power will not
increase above the maximum allowed value due to an increased mains voltage. In the
feed-forward range the UBA2021 driver IC can be configured in such a way that the
application is optimized for close to constant lamp power. Above a defined voltage level
the oscillation frequency also depends on the supply voltage of the half-bridge (see
Figure 6).
The current for the current controlled oscillator is derived from the current
through R
RHV
in the feed-forward range. The feed-forward frequency is proportional to the
average value of the current through R
RHV
within the operating range of I
i(RHV)
, given the
lower limit set by f
B
. For currents beyond the operating range (i.e. between 1.0 mA and 1.6
mA) the feed-forward frequency is clamped. In order to prevent feed-forward of ripple on
UBA2021_4
© NXP B.V. 2008. All rights reserved.
Product data sheet
Rev. 04 — 25 July 2008
5 of 16
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