AN10932_15 Datasheet, PDF (26/33 Pages) NXP Semiconductors – 120 V high power factor dimmable CFL with UBA2014

NXP Semiconductors
AN10932
120 V high power factor dimmable CFL with UBA2014
AN10932
Application note
When calculating the current in the MOSFETs, the average boost current over a line cycle
is considered which is shown in Equation 32.
π^{-2- ⋅ (Iboost(t))}
(32)
In addition, I_hb(t) is subtracted from I_boost(t) because I_hb(t) is the current flowing out of
V_hb(t) node. V_hb1(t) is the first harmonic of the V_hb(t).
1000
voltage
(V)
500
(3)
(5)
(2)
(4)
(1)
1.5
current
(A)
1.0
0.5
0
0
−0.5
0
5
10
15
20
25
30
t (μs)
019aaa351
(1) V_hb1(t)
(2) V_hb(t)
(3) I_hb(t) + I_boost(t)
(4) I_hb(t)
(5) I_boost(t)
Fig 20. Voltage and currents at half-bridge
In order to calculate the rise and fall times of the half-bridge voltage, the instantaneous
boost current I_boost and the
shown in equations below:
instantaneous bridge
current I_hb at
T_--
2
and T
are
calculated as
I_h
⎛
b_⎝
T_{-2-⎠⎞}
=
0.262
[A]
(33)
I_hb(T) = –0.262 [A]
(34)
I_bo
⎛
ost_⎝
T_{-2-⎠⎞}
=
2.171 [mA]
(35)
I_boost(T) = 0.684 [A]
(36)
It_f
=
I_b
oo
⎛
st_⎝
T_{-2-⎠⎞}
+
I_hb
⎛
⎝
T_{-2-⎠⎞}
=
0.264
[mA]
(37)
All information provided in this document is subject to legal disclaimers.
Rev. 2 — 17 January 2011
© NXP B.V. 2011. All rights reserved.
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