AN10907
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© NXP B.V. 2010. All rights reserved.
Application note
Rev. 1 — 28 December 2010
35 of 82
NXP Semiconductors
AN10907
TEA1613T resonant power supply control IC
The similarity when switching GATELS and GATEHS is that the oscillator signal
determines the moment of switching off. The moment of switching on is determined by the
HB sensing circuit.
As the moment of switching on is determined by the HB sensing (and therefore not fixed),
the time between switching one MOSFET off and the other one on, is adaptive
non-overlap time (or dead time). This non-overlap time has no influence on the oscillator
signal.
The frequency control by oscillator frequency consists of determining the time between
two moments of switching off (including a small period during which the oscillator current
is only 30
A).
8.4.3 CFMIN and RFMAX
This section explains the method of calculating the values for the capacitor on CFMIN and
the resistor on RFMAX.
8.4.3.1
Minimum frequency setting for CFMIN
(9)
(10)
(11)
(12)
Fig 22. Timing overview of the oscillator and HBC drive
GateLs
GateHs
Hb
30
μ
A-period
I
TrHbc
C
fmin
t
V
boost
0
001aal446
f
oscillator
2
f
HB
=
t
ch
e
arg
t
disch
e
arg
t
oscillator
2
----------------------
V
oscillator
V
high CFMIN
V
low CFMIN
3
V
1
V
2
V
=
–
=
–
=
I
oscillator min
150
A
=
