AN10971_15 Datasheet, PDF (9/41 Pages) NXP Semiconductors – TL applications with NXP ballast controllers

NXP Semiconductors
AN10971
TL applications with NXP ballast controllers
DS1
R1
mains
supply
L1
DS2
C3
C2
V_i
S1
lamp
L2
C5
S2
DS3
DS4
C4
Rshunt
Fig 9. S1 and S2 driven by UBA2021
RRHV
490 kΩ
G1
2
RHV
13
14 ^CI
CCI
100 nF
S1
3
CCP
8 ^CP
100 nF
100 nF
CS7
FS
1
Cboot
UBA2021 ₁₂ CF
CCF
100 pF
G2 ₆
DS7
VS _{5 7}
RREF ^RRREF
10
30 kΩ
SGND
9 ¹¹
CS4 DS6
CS9
PGND RS
mgs994
When the lamp is ignited, the phase shift of the Inductor Resistor Capacitor (LRC) L2, C5
and lamp combination above its resonance frequency is such that the current lags behind.
The voltage current phase shift of an inductor is similar. Figure 10 shows the coil current
amplitude of LRC resonant tank versus frequency while Figure 11 shows the phase
relationship.
Amplitude A
40 kHz
100 kHz
019aaa667
Fig 10. Current amplitude of LRC resonant tank versus frequency
Phase
+90
−90
40 kHz
100 kHz
019aaa668
Fig 11. Current phase of LRC resonant tank versus frequency
AN10971
Application note
All information provided in this document is subject to legal disclaimers.
Rev. 1 — 15 September 2011
© NXP B.V. 2011. All rights reserved.
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