Infineon CoolSET-F3R ICE3BRXX65JG series, Руководство по конструкции, Страница: 21 / 22

ICE3BRXX65J(Z)(G)
Application Note 21 2010-06-20
10 Useful formula & external component design
Transformer calculation (DCM flyback)
Input data
V
in_min
= 90Vdc, V
in_max
= 380Vdc,
V
ds_max
= 470V for 600V MOSFET,
D
max
≤ 50%
Turn ratio
diode out
in ds
ratio
V V
V V
N
+
−
= max _ max _
Maximum Duty ratio
ratio diode out in
ratio diode out
N V V V
N V V
D
⋅ + +
⋅ +
=
) (
) (
min _
max
Primary Inductance
sw in
in
p
f P
D V
L
⋅ ⋅
⋅
≤
2
) (
2
max min _
Primary peak current
sw p
in
p
f L
D V
I
⋅
⋅
=
max min _
max _
Primary turns
min max
max _
A B
L I
N
p p
p ⋅
⋅
≥
Secondary turns
ratio
p
s
N
N
N
=
Auxiliary turns
s
diode out
diode cc
aux
N
V V
V V
N
⋅
+
+
=
ICE3BRXX65J(Z)(G) external component Design
Current sense resistor
max _ p
csth
sense
I
V
R
≤
Soft start time
ms t
ss
20
=
Vcc capacitor
3
2
2 sup
×
×
=
VCChys
ss VCC
VCC
V
t I
C
Startup delay time
3 arg e VCCch
Vcc VCCon
DELAY
I
C V
t
×
=
Enter burst mode power
SW
V sense
Ramp Offset FBC
P enter BURST
f
A R
V V
L P
×
×
−
× × =
−
2 5
_
) ( 5 . 0
Leave burst mode power
SW p P burst
f I L P
× × × × =
2
max _ max _
) 34 . 0 ( 5 . 0