AN_UBA2024T
Philips Semiconductors
CFL applications with the UBA2024T APPLICATION NOTE
APPLICATION NOTE
CFL applications with the
UBA2024T
Author(s):
Joost Bongers, Arjan van den Berg, Ben Verhoeven
Philips Semiconductors, Standard Analogue Business line, Nijmegen, The Netherlands
Keywords:
C ompact F luorescent L amp
Quasi preheat
UBA2024T
Integrated half bridge driver
S ilicon O n I nsulator
Date: 2003-August-25
CFL applications with the UBA2024T APPLICATION NOTE
1INTRODUCTION (4)
2FEATURES (4)
3Application photos (5)
4Circuit Diagram (6)
5SELECTING COMPONENT VALUES (7)
5.1Selecting input configuration, buffer capacitor and fuse-resistor (7)
5.2Choosing frequency, lamp inductor and lamp capacitor (7)
5.3Ignition frequency and preheating (9)
5.4Choosing the other components (9)
5.5About component tolerances (9)
6EXAMPLES OF CALCULATING COMPONENT VALUES (11)
6.1EXAMPLE 1: a 3W lamp (2.5W/90mA burner) (11)
Determining component values for 115V/60Hz mains (11)
Determining component values for 230V/50Hz mains (11)
6.2EXAMPLE 2: a 14W lamp (12W/150mA burner, suited for cold ignition) (12)
Determining component values for 115V/60Hz mains (12)
Determining component values for 230V/50Hz mains (12)
6.3Some other examples (13)
8W lamp (7W/150mA burner, suited for cold ignition) (f out=46kHz) (13)
11W lamp (9.5W/150mA burner, suited for cold ignition) (f out=42.5kHz) (13)
13W lamp (11W/125mA burner, needing warm ignition) (f out=42.5kHz) (14)
15W lamp (12.5W/180mA burner, suited for cold ignition) (f out=40kHz) (14)
12W DEMO BOARD LAMP : (15)
7QUICK MEASUREMENTS (16)
APPENDIX 1Application board layout exa mple (18)
CFL applications with the UBA2024T APPLICATION NOTE
1INTRODUCTION
The UBA2024T is an integrated half bridge power IC, designed for use in an integrated / sealed Compact Fluorescent Lamp (CFL) with a lamp current up to 150mA. Typical input voltages are
100-127Vac and 220-240Vac. Output power varies from 3 to 15W, depending on lamp and input voltage.
The UBA2024T is a high voltage (550V) monolithic integrated circuit made in the EZ-HV SOI process. It includes both half bridge power transistors with level-shifter and drivers, boots trap circuitry, an internal power supply, a precision oscillator and a start-up frequency sweep function for soft-start
and/or pre-heating. It is mounted in a dedicated SO14 (Small Outline) package with optimised heat transfer.
Due to the high level of integration, only few external components are needed when building a lamp ballast with the UBA2024T. This application note will give descriptions of typical integrated CFL applications in the 3 to 15W range.
(See datasheet for functional description of the UBA2024T)
2FEATURES
?based upon EZ-HV SOI (silicon on insulator) technology
?integrated half bridge power-IC for CFL applications (both powers and controller)
?accurate oscillator with adjustable frequency
?Soft start by frequency sweep down from start frequency
?Quasi preheat option (by use of larger sweep down timing)
?Allows for very compact integrated lamp ballast which fits a small shell
?Low cost Compact Fluorescent Lamp applications due to low component count
?Easy applicable
?Can withstand 550V maximum voltage surge
CFL applications with the UBA2024T APPLICATION NOTE 3APPLICATION PHOTOS
Figure 1: Photos of a 14W Compact Fluorescent Lamp with UBA2024T
CFL applications with the UBA2024T
APPLICATION NOTE
4 CIRCUIT DIAGRAM
Figure 2: Schematic of Compact Fluorescent Lamp application using the UBA2024T
with voltage doubler input
Figure 3: Schematic of standard Compact Fluorescent Lamp application using UBA2024T
PINNING SO14
SYMBOL PIN DESCRIPTION SYMBOL
PIN DESCRIPTION
SGND 1signal ground SW 8input for sweep timing SGND 2signal ground SGND 9signal ground SGND 3signal ground SGND 10signal ground
HV 4high voltage supply FS 11floating supply high side SGND 5signal ground PGND 12power ground VDD 6internal low voltage supply SGND 13signal ground RC 7input for internal oscillator
OUT 14
half bridge output
100-240V 50/60Hz
VDD
100-127V 50/60Hz
VDD
CFL applications with the UBA2024T
APPLICATION NOTE
5 SELECTING COMPONENT VALUES
5.1
Selecting input configuration, buffer capacitor and fuse-resistor
Use of a voltage doubler (figure 2) or standard bridge rectifier (figure 3), values for the buffer capacitor (C BUF ) and the fusible inrush-current limiting resistor are given in table 2:
Table 2: Adviced input configuration, buffer capacitor en fusible inrush-current limiting resistor
Input Voltage Lamp Power #Input configuration C BUF C BUF1, C BUF2 (each)R FUS
100-127Vac ≤ 4 W 10μF/200V
(n.a.)18? (0.25W/23W)*100-127Vac 5 – 6 W Standard (fig. 4)
15μF/200V (n.a.)12? (0.5W/35W)*100-127Vac 7 – 8 W (n.a.)10μF/200V
10? (0.5W/47W)*100-127Vac 9 –11 W (n.a.)15μF/200V
8.2? (0.75W/70W)*100-127Vac 12 – 14 W Voltage Doubler
(fig.3)
(n.a.)22μF/200V 6.8? (1W/103W)*220-240Vac ≤ 5 W 2.2μF/400V (n.a.)47? (0.25W/23W)*220-240Vac 6 – 8 W 3.3μF/400V
(n.a.)39? (0.25W/23W)*220-240Vac 9 – 11 W 4.7μF/385V (n.a.)33? (0.5W/32W)*220-240Vac 12 – 15 W Standard (fig. 4)
6.8μF/385V (n.a.)27? (0.5W/47W)*
(# Overall lamp power including driver circuit)
(* Minimum continuous power rating / minimum peak power rating (≤20ms))
5.2 Choosing frequency, lamp inductor and lamp capacitor
Given a certain netto 1 lamp power P lamp and lamp current I lamp , then V lamp =P lamp /I lamp . If buffer capacitors are according to table 2, an approximation of the effective lamp inductor voltage V Lla_eff is given 2 in table 3:
Table 3: Approximated effective lamp inductor voltage
V_lamp Input Voltage frequency Input configuration ≤20V ≈30V ≈40V ≈50V ≈60V ≈80V ≈100V 100 Vac 585346n.a.n.a.
n.a.n.a.115 Vac 71666253n.a.n.a.n.a.127 Vac 60 Hz Standard (fig. 4)
80767065n.a.n.a.n.a.100 Vac 123120117113108
94n.a.115 Vac 145143140137133
122107127 Vac 60 Hz Voltage Doubler (fig.3)164162160157154
144131220 Vac 138136133130125
11295230 Vac 145143140138134122106240 Vac 50 Hz Standard (fig. 4)
153151148146143131
116
V L l a _e f f [V ]
The lamp inductor L LA and the lamp frequency f out have to comply to:
I V
L f 2lamp
Lla_eff
LA out =π
1 of burner only, usually about 85% of overall lamp power.
2 use linear interpolation to find values inbetween.
CFL applications with the UBA2024T
APPLICATION NOTE
f out can be chosen freely up to 60kHz (the maximum nominal output frequency for the UBA2024, correspondin
g wit
h a start-up frequency of 150kHz, see datasheet for start-up sequence description). However, usually f out is chosen between 25kHz and 30kHz or between 40kHz and 50kHz. This is because below 25kHz there may be audible noise,operation in the 30kHz to 40kHz band may result in interference with infra-red remote control and above 50kHz the third harmonic is in the range where conducted noise requirements for most countries have to be met. Since inductors and capacitors decrease in size and cost with increase in frequency, the 40 to 50kHz range is preferred.Throughout this application note we will presume the lamp frequency will be in this range.f out is set by R OSC and C OSC according to the following formula:
OSC
OSC OSC out C R k 1
f =Practical values for R OSC range from 50k ? to 400k ?. Note that the low values of R OSC will cause a larger VDD output current, thus increasin
g the total package dissipation. Practical values for C OSC range from 100pF to 1nF.Advised value for C OSC is 180pF for 40..50kHz and 270pF for 25..30kHz. The oscillator constant k OSC is shown in figure 4.
Figure 4: Typical k osc dependency of R osc and C osc for UBA2024T.
CFL applications with the UBA2024T APPLICATION NOTE
5.3Ignition frequency and preheating
The IC starts at an output frequency of about 21/2 times the nominal output frequency, and gradually decreases this until the nominal output frequency is reached. The lamp inductor L LA and the lamp capacitor C LA will boost the lamp voltage gradually higher as the output frequency gets closer to their resonance frequency, until it is sufficient to ignite
the lamp. In the mean time the current in the resonance circuit flows through the filaments thereby providing some preheating. The UBA2024 has a circuit that stops the frequency sweep at the resonance frequency if the lamp has not ignited yet (see UBA2024 specifications for details). This ensures maximum effort to ignite the lamp.
The ignition frequency f ign is higher than or equal to the resonance frequency of L LA and C LA (f res=1/(2π√(L LA C LA)) ). The resonance frequency should be choosen so that 1.6?f out≤f res≤1.8?f out. The time needed to sweep down (set by
C SW) from the start frequency to f res can be used as an approximation for the ignition time. It’s about 0.5s/100nF. For large values the ignition time is shorter, because the lamp ignites before the resonance frequency is reached. Typical ignition time is 1 s when C SW=330nF.
C SW determines the sweep time. The larger C SW, the longer the sweep time and better the preheating of the electrodes. However, the rise of the pre-ignition lamp voltage is also slower. Both a too short preheat as well as a too slow voltage rise increase the glow time of the lamp (that’s when the lamp is not yet fully ignited, but it’s not off anymore either), which decreases lamp life time. The best preheat time strongly depends on the lamp. Typical values for C SW are 33nF to 330nF.
5.4Choosing the other components
?For D1..D4 plain low cost 1N4007 diodes can be used.
?For lamp current ≥150mA C DV=220pF, for lower currents C DV=100pF.
?The values for C VDD and C FS are C FS=C VDD=10nF.
?Advised half bridge capacitors (C HB1 and C HB2) are >47nF when f out= 40–50kHz and >68nF when f out= 25–30 kHz.
?The resonance frequency of the input filter, consisting of L FILT and C HB (C HB being de effective capacitor as seen on the HV pin of the IC, i.e. the series capacitance of C HB1 and C HB2), has to be at least two times lower than the nominal output frequency.
Note: Performance and lifetime can not be guaranteed by using the values given in this chapter only. Lamp and UBA2024 performance strongly interact with each other and need to be qualified together as a combination.
5.5About component tolerances
For all components, generally used tolerances can be used (20% for electrolytic capacitors, 10% for other capacitors (foil or ceramic) and 5% for resistors and inductors). Since R OSC, C OSC and L LA determine the lamp current, their tolerance also determines the spread in the lamp current. Therefore, the required lamp current accuracy may require closer tolerance R OSC, C OSC and L LA.
Example 1: R OSC±5%, C OSC±10%, L LA±5%, C LA±10% and the IC’s internal frequency ±3% then lamp current tolerance is 12.6% effective3.
3 Valid for component values with normal distribution.
CFL applications with the UBA2024T APPLICATION NOTE Example 2: R OSC±1%, C OSC±5%, L LA±5%, C LA±5% and the IC’s internal frequency ±3% then lamp current tolerance is 7.1% effective.
CFL applications with the UBA2024T
APPLICATION NOTE
6 EXAMPLES OF CALCULATING COMPONENT VALUES 6.1
EXAMPLE 1: a 3W lamp (2.5W/90mA burner)
Determining component values for 115V/60Hz mains
1) From table 2: Standard configuration, C BUF =10μF, R FUS =18?.
2) V lamp ≈2.5/0.090≈28V. From table 3: Effective lamp coil voltage V Lla_eff ≈ 68V. For L LA =3.9mH the output
frequency must be f out =68/(0.090?3.9?10-3?2?π)=30.8kHz 3) We choose C OSC =270pF, then R OSC =1/(1.07?30.8?103?270?10-12)=112k ?. To stay below 30kHz and within E24-range we choose 120k ?, so f out =1/(1.07?120?103?270?10-12)=28.8kHz.4) The only E12-range value of C LA resulting in f ign /f out between 1.6 and 1.8 is: 2.7nF (f ign /f out ≈1.70).5) Warm ignition. C SW =220nF.
6) D 1..D 4=BYD13M (=1N4007 equivalent, but smaller), C FS =10nF, C VDD =10nF and C DV =100pF (see section 6.4).7) C HB1=C HB2=33nF (see section 6.4). L FILT is choosen 4.7mH.
Determining component values for 230V/50Hz mains
1) From table 2: Standard configuration, C BUF =2.2μF, R FUS =47?.
2) V lamp ≈2.5/0.090≈28V. From table 3: Effective lamp coil voltage V Lla_eff ≈ 143V. For L LA =8.2 mH the output
frequency must be f out =143/(0.090?8.2?10-3?2?π)=30.8kHz 3) We choose C OSC =270pF, then R OSC =1/(1.07?30.8?103?270?10-12)=112k ?. To stay below 30kHz and within E24-range we choose 120k ?, so f out =1/(1.07?120?103?270?10-12)=28.8kHz.4) The only E6-range value of C LA resulting in f ign /f out between 1.6 and 1.8 is 1.0nF (f ign /f out ≈1.76).5) Warm ignition: C SW =220nF.
6) D 1..D 4=BYD13M (=1N4007 equivalent, but smaller), C FS =10nF, C VDD =10nF and C DV =100pF (see section 6.4).7) C HB1=C HB2=47nF (see section 6.4). L FILT is choosen 4.7mH.
REF DESCRIPTION
REMARKS 115V/60HZ
230V/50Hz R FUS Fusible inrush current limiter resistor
Special type, fusible, high peak power 18?
47?
D 1..D 4Bridge rectifier diodes BYD13M
BYD13M C BUF Buffer capacitor High temperature electrolytic type 10μF/200V 2.2μF/400V L FILT
Filter inductor
Axial type 4.7mH
4.7mH
C HB1, C HB2Half bridge capacitors 47nF/200V dc
47nF/200V dc C LA Lamp capacitor Foil type 2.7nF/1kV dc 1.0nF/1kV dc L LA Lamp inductor
BC7/12-Core (illustration at the side) 3.9mH.
8.2mH
C DV dV/dt limiting capacitor
100pF/500V dc 100pF/500V dc C FS Floating Supply buffer capacitor 10nF/50V 10nF/50V C VDD low voltage supply buffer capacitor 10nF/50V 10nF/50V C OSC Oscillator capacitor 270pF/50V 270pF/50V R OSC Oscillator resistor 120k ?/1/8W 120k ?/1/8W C SW
Sweep time capacitor
220nF/16V
220nF/16V
CFL applications with the UBA2024T APPLICATION NOTE
6.2EXAMPLE 2: a 14W lamp (12W/150mA burner, suited for cold ignition)
Determining component values for 115V/60Hz mains
1)From table 2: Voltage doubler configuration, C BUF1=C BUF2=22μF, R FUS=6.8?
2)V lamp≈12/0.150=80V. From table 3: Effective lamp coil voltage V Lla_eff≈ 122V. For L LA=3.1mH the output
frequency must be f out=122/(0.150?3.1?10-3?2?π)=41.8kHz.
3)We choose C OSC=180pF, then R OSC=1/(1.09?41.8?103?180?10-12)=122k?. To stay within E24-range we choose
120k?, so f out=1/(1.09?120?103?180?10-12)=42.5kHz.
4)The only E6-range value of C LA resulting in f ign/f out between 1.6 and 1.8 is 1.5nF (f ign/f out≈1.74).
5)This burner is suited for cold ignition: C SW=100nF (see paragraph 5.3)
6)D1=D2=1N4007, C FS=10nF, C VDD=10nF and C DV=220pF (see section 6.4).
7)C HB1=C HB2=47nF (see section 6.4). L FILT is choosen 2.7mH.
Determining component values for 230V/50Hz mains
1)From table 2: Standard configuration, C BUF=6.8μF, R FUS=27?
2)V lamp≈12/0.150=80V. From table 3: Effective lamp coil voltage V Lla_eff≈ 122V. For L LA=3.1mH the output
frequency must be f out=122/(0.150?3.1?10-3?2?π)=41.8kHz.
3)We choose C OSC=180pF, then R OSC=1/(1.09?41.8?103?180?10-12)=122k?. To stay within E24-range we choose
120k?, so f out=1/(1.09?120?103?180?10-12)=42.5kHz.
4)The only E6-range value of C LA resulting in f ign/f out between 1.6 and 1.8 is 1.5nF (f ign/f out≈1.74).
5)For cold ignition C SW=33nF (see paragraph 5.3)
6)D1..D4=1N4007, C FS=10nF, C VDD=10nF and C DV=220pF (see section 6.4).
7)C HB1=C HB2=47nF (see section 6.4). L FILT is choosen 2.7mH.
REF DESCRIPTION REMARKS115V/60HZ230V/50Hz R FUS Fusible inrush current limiter resistor Special type, fusible, high peak power 6.8?27?
D1, D2Voltage doubler diodes1N4007
D1..D4Bridge rectifier diodes1N4007
C BUF1, C BUF2Buffer capacitors High temperature electrolytic type22μF/200V
C BUF Buffer capacitor High temperature electrolytic type 6.8μF/400V
L FILT Filter inductor Axial type 2.7mH 2.7mH
C HB1, C HB2Half bridge capacitors47nF/200V dc47nF/200V dc
C LA Lamp capacitor Foil type, capable of withstanding peak
1.5nF/400V dc 1.5nF/400V dc
voltages of twice it’s dc rating
L LA Lamp inductor E-16-Core 3.1mH 3.1mH
C DV dV/dt limiting capacitor220pF/500V dc220pF/500V dc
C FS Floating Supply buffer capacitor10nF/50V10nF/50V
C VD
D low voltage supply buffer capacitor10nF/50V10nF/50V
C OSC Oscillator capacitor180pF/50V180pF/50V
R OSC Oscillator resistor120k?/1/8W120k?/1/8W
C SW Sweep time capacitor100nF/25V33nF/50V
CFL applications with the UBA2024T APPLICATION NOTE
6.3Some other examples
8W lamp (7W/150mA burner, suited for cold ignition) (f out=46kHz)
REF DESCRIPTION REMARKS115V/60HZ230V/50Hz R FUS Fusible inrush current limiter resistor Special type, fusible, high peak power10?39?
D1, D2Voltage doubler diodes1N4007
D1..D4Bridge rectifier diodes1N4007
C BUF1, C BUF2Buffer capacitors High temperature electrolytic type10μF/200V
C BUF Buffer capacitor High temperature electrolytic type 3.3μF/400V
L FILT Filter inductor Axial type 2.2mH 2.2mH
C HB1, C HB2Half bridge capacitors47nF/200V dc47nF/200V dc
1.5nF/400V dc 1.5nF/400V dc
C LA Lamp capacitor Foil type, capable of withstanding peak
voltages of twice it’s dc rating
L LA Lamp inductor E-16-Core 3.1mH 3.1mH
C DV dV/dt limiting capacitor220pF/500V dc220pF/500V dc
C FS Floating Supply buffer capacitor10nF/50V10nF/50V
C VD
D low voltage supply buffer capacitor10nF/50V10nF/50V
C OSC Oscillator capacitor180pF/50V180pF/50V
R OSC Oscillator resistor110k?/1/8W110k?/1/8W
C SW Sweep time capacitor100nF/25V33nF/50V
11W lamp (9.5W/150mA burner, suited for cold ignition) (f out=42.5kHz)
REF DESCRIPTION REMARKS115V/60HZ230V/50Hz R FUS Fusible inrush current limiter resistor Special type, fusible, high peak power8.2?33?
D1, D2Voltage doubler diodes1N4007
D1..D4Bridge rectifier diodes1N4007
C BUF1, C BUF2Buffer capacitors High temperature electrolytic type15μF/200V
C BUF Buffer capacitor High temperature electrolytic type 4.7μF/400V
L FILT Filter inductor Axial type 2.7mH 2.7mH
C HB1, C HB2Half bridge capacitors47nF/200V dc47nF/200V dc
C LA Lamp capacitor Foil type, capable of withstanding peak
1.5nF/400V dc 1.5nF/400V dc
voltages of twice it’s dc rating
L LA Lamp inductor E-16-Core 3.1mH 3.1mH
C DV dV/dt limiting capacitor220pF/500V dc220pF/500V dc
C FS Floating Supply buffer capacitor10nF/50V10nF/50V
C VD
D low voltage supply buffer capacitor10nF/50V10nF/50V
C OSC Oscillator capacitor180pF/50V180pF/50V
R OSC Oscillator resistor120k?/1/8W120k?/1/8W
C SW Sweep time capacitor100nF/25V33nF/50V
CFL applications with the UBA2024T APPLICATION NOTE 13W lamp (11W/125mA burner, needing warm ignition) (f out=42.5kHz)
REF DESCRIPTION REMARKS115V/60HZ230V/50Hz R FUS Fusible inrush current limiter resistor Special type, fusible, high peak power 6.8?27?
D1, D2Voltage doubler diodes1N4007
D1..D4Bridge rectifier diodes1N4007
C BUF1, C BUF2Buffer capacitors High temperature electrolytic type22μF/200V
C BUF Buffer capacitor High temperature electrolytic type 6.8μF/400V
L FILT Filter inductor Axial type 3.9mH 3.9mH
C HB1, C HB2Half bridge capacitors33nF/200V dc33nF/200V dc
1.5nF/400V dc 1.5nF/400V dc
C LA Lamp capacitor Foil type, capable of withstanding peak
voltages of twice it’s dc rating
L LA Lamp inductor E-16-Core 3.5mH 3.5mH
C DV dV/dt limiting capacitor100pF/500V dc100pF/500V dc
C FS Floating Supply buffer capacitor10nF/50V10nF/50V
C VD
D low voltage supply buffer capacitor10nF/50V10nF/50V
C OSC Oscillator capacitor180pF/50V180pF/50V
R OSC Oscillator resistor120k?/1/8W120k?/1/8W
C SW Sweep time capacitor470nF/16V330nF/16V
15W lamp (12.5W/180mA burner, suited for cold ignition) (f out=40kHz)
REF DESCRIPTION REMARKS230V/50Hz R FUS Fusible inrush current limiter resistor Special type, fusible, high peak power27?
D1..D4Bridge rectifier diodes1N4007
C BUF Buffer capacitor High temperature electrolytic type 6.8μF/400V
L FILT Filter inductor Axial type 3.3mH
C HB1, C HB2Half bridge capacitors47nF/200V dc
1.8nF/400V dc
C LA Lamp capacitor Foil type, capable of withstanding peak
voltages of twice it’s dc rating
L LA Lamp inductor E-16-Core 3.1mH
C DV dV/dt limiting capacitor220pF/500V dc
C FS Floating Supply buffer capacitor10nF/50V
C VD
D low voltage supply buffer capacitor10nF/50V
C OSC Oscillator capacitor180pF/50V
R OSC Oscillator resistor130k?/1/8W
C SW Sweep time capacitor68nF/50V
CFL applications with the UBA2024T APPLICATION NOTE 12W DEMO BOARD LAMP :
12W lamp (150mA burner, cold ignition, f out=46kHz)
REF DESCRIPTION REMARKS230V/50Hz R FUS Fusible inrush current limiter resistor Special type, fusible, high peak power10?
D1..D4Bridge rectifier diodes1N4007
C BUF Buffer capacitor High temperature electrolytic type 3.3μF/400V
L FILT Filter inductor Axial type 1.8mH
C HB1, C HB2Half bridge capacitors100nF/200V dc
2.2nF/400V dc
C LA Lamp capacitor Foil type, capable of withstanding peak
voltages of twice it’s dc rating
L LA Lamp inductor E-16-Core 2.7mH
C DV dV/dt limiting capacitor220pF/500V dc
C FS Floating Supply buffer capacitor10nF/50V
C VD
D low voltage supply buffer capacitor10nF/50V
C OSC Oscillator capacitor180pF/50V
R OSC Oscillator resistor110k?/1/8W
C SW Sweep time capacitor33nF/50V
CFL applications with the UBA2024T APPLICATION NOTE
7QUICK MEASUREMENTS
Table 4: Measured values compared with calculated values
Lamp power Input voltage
/frequency4
Input
configuration
preheat f out set f out
measured5
I lamp calculated
using f out measured
I lamp
measured
3W115V/50Hz standard Yes28.8kHz29.1kHz95mA97mA
3W230V/50Hz standard Yes28.8kHz29.0kHz96mA94mA
8W115V/60Hz doubler No45.9kHz48.7kHz145mA138mA
8W230V/50Hz standard No45.9kHz48.6kHz147mA144mA
11W115/60Hz doubler No42.5kHz45.1kHz148mA142mA
11W230V/50Hz standard No42.5kHz44.7kHz150mA148mA
13W115/60Hz doubler maximum42.5kHz44.0kHz120mA115mA
13W230V/50Hz standard maximum42.5kHz44.0kHz120mA127mA
14W115V/60Hz doubler No42.5kHz45.2kHz139mA129mA
14W230V/50Hz standard No42.5kHz44.8kHz140mA141mA
15W230V/50Hz standard No39.7kHz41.4kHz161mA171mA
Figure 5: Cold starting lamp waveforms.
(C SW=10nF)
4 Measurement for 115V/60Hz were done at 115V/50Hz with 15% extra capacitance added to C BUF1 and C BUF2.
5 A 5% resistor was used for Rosc, and a 10% capacitor was used for Cosc. Tolerances of Rosc and Cosc both add to frequancy tolerance of IC. Use Rosc and Cosc with less tolerance if better match between calculated and measured frequency is needed.
CFL applications with the UBA2024T APPLICATION NOTE
Figure 6: Lamp start-up with ‘warm’ ignition.
(C SW=330nF)
CFL applications with the UBA2024T APPLICATION NOTE
APPENDIX 1Application board layout example
The layout of the PCB on which the UBA2024T is mounted, has a considerable influence on the performance of the IC. Issues to be taken into account are:
?Coils with open magnetic circuit should not be placed above the IC (on the other side of the PCB). If an axial filter inductor is used for L FILT it should be placed in the same direction as the IC to minimize magnetic field pick-up.
?All output components (C HB1, C HB2, L LA, C LA and C DV) and their interconnections should be placed at the side of pin 1 and pin 14 of the IC.
?Oscilator pin (pin 7, “RC”) and sweep pin (pin 8, “SW”) should be shielded form output/lamp by a ground track.
Components on these pins should be placed as close to the IC as possible.
?Capacitors C VDD and C FS should be placed close to the IC.
?For effective heat transfer all SGND pins need to be soldered to a copper plane which is also beneath the IC and extends besides the IC as much as possible. Fixing the IC to the board using thermal conductive glue also helps. Of course, the size and shape of the PCB has to fit the lamp base. Below the layout of the demoboard, as is used for the measurements mentioned in this application note, is shown as an example. With it’s diameter of only 35mm it’s smaller then most currently used CFL-ballast PCBs. It’s suited for either use of the popular E16 core lamp inductor or a radial-type I-core inductor.
Figure 7: Layout (left) and component placement (right) of application demoboard
(actual size is 35mm diameter)