AN_UBA2024T_15 Datasheet, PDF (11/18 Pages) NXP Semiconductors – CFL applications

Philips Semiconductors
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, CBUF=10µF, RFUS=18Ω.
2) Vlamp≈2.5/0.090≈28V. From table 3: Effective lamp coil voltage VLla_eff ≈ 68V. For LLA=3.9mH the output
frequency must be fout=68/(0.090⋅3.9⋅10^-3⋅2⋅π)=30.8kHz
3) We choose COSC=270pF, then ROSC=1/(1.07⋅30.8⋅10³â‹…270⋅10^-12)=112kΩ. To stay below 30kHz and within E24-
range we choose 120kΩ, so fout=1/(1.07⋅120⋅10³â‹…270⋅10^-12)=28.8kHz.
4) The only E12-range value of CLA resulting in fign/fout between 1.6 and 1.8 is: 2.7nF (fign/fout ≈1.70).
5) Warm ignition. CSW=220nF.
6) D1..D4=BYD13M (=1N4007 equivalent, but smaller), CFS=10nF, CVDD=10nF and CDV=100pF (see section 6.4).
7) CHB1=CHB2=33nF (see section 6.4). LFILT is choosen 4.7mH.
Determining component values for 230V/50Hz mains
1) From table 2: Standard configuration, CBUF=2.2µF, RFUS=47Ω.
2) Vlamp≈2.5/0.090≈28V. From table 3: Effective lamp coil voltage VLla_eff ≈ 143V. For LLA=8.2 mH the output
frequency must be fout=143/(0.090⋅8.2⋅10^-3⋅2⋅π)=30.8kHz
3) We choose COSC=270pF, then ROSC=1/(1.07⋅30.8⋅10³â‹…270⋅10^-12)=112kΩ. To stay below 30kHz and within E24-
range we choose 120kΩ, so fout=1/(1.07⋅120⋅10³â‹…270⋅10^-12)=28.8kHz.
4) The only E6-range value of CLA resulting in fign/fout between 1.6 and 1.8 is 1.0nF (fign/fout ≈1.76).
5) Warm ignition: CSW=220nF.
6) D1..D4=BYD13M (=1N4007 equivalent, but smaller), CFS=10nF, CVDD=10nF and CDV=100pF (see section 6.4).
7) CHB1=CHB2=47nF (see section 6.4). LFILT is choosen 4.7mH.
REF
RFUS
D1..D4
CBUF
LFILT
CHB1, CHB2
CLA
LLA
CDV
CFS
CVDD
COSC
ROSC
CSW
DESCRIPTION
Fusible inrush current limiter resistor
Bridge rectifier diodes
Buffer capacitor
Filter inductor
Half bridge capacitors
Lamp capacitor
Lamp inductor
dV/dt limiting capacitor
Floating Supply buffer capacitor
low voltage supply buffer capacitor
Oscillator capacitor
Oscillator resistor
Sweep time capacitor
REMARKS
Special type, fusible, high peak power
High temperature electrolytic type
Axial type
Foil type
BC7/12-Core (illustration at the side)
115V/60HZ
18Ω
BYD13M
10µF/200V
4.7mH
47nF/200V dc
2.7nF/1kV dc
3.9mH.
100pF/500V dc
10nF/50V
10nF/50V
270pF/50V
120kΩ/1/8W
220nF/16V
230V/50Hz
47Ω
BYD13M
2.2µF/400V
4.7mH
47nF/200V dc
1.0nF/1kV dc
8.2mH
100pF/500V dc
10nF/50V
10nF/50V
270pF/50V
120kΩ/1/8W
220nF/16V
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