Owner's manual
AN368
AN368REV2 55
Calculate the MOSFET ‘ON’ time T1
CH1
in Mode 1 using Equation 20:
Calculate the MOSFET ‘ON’ time T1
CH2
in Mode 2 using Equation 21:
Calculate the MOSFET ‘OFF’ time T2
CH1
in Mode 1 using Equation 22:
Calculate the MOSFET ‘OFF’ time T2
CH2
in Mode 2 using Equation 23:
f. Calculate the Flyback Primary-side Inductance
Calculate the flyback transformer primary-side inductance, L
P
, using Equation 24:
g. Calculate Peak Current on the Flyback Primary-side
Calculate peak current I
PK1(FB)
during Mode 1 using Equation 25:
Calculate peak current I
PK2(FB)
during Mode 2 using Equation 26:
Calculate the average current I
MODE1(avg)
during Mode 1 using Equation 27:
Calculate the average current I
MODE2(avg)
during Mode 2 using Equation 28:
T1
CH1
TT
CH1
T3
CH1
–D
MODE1
14.29s0.37 5.3s===
[Eq. 99]
T1
CH2
TT
CH2
T3
CH2
–D
MODE2
18.76s0.22 4.2s===
[Eq. 100]
T2
CH1
TT
CH1
T1
CH1
– T3
CH1
– 15.29s5.3s– 1s– 9.0s===
[Eq. 101]
T2
CH2
TT
CH2
T1
CH2
– T3
CH2
– 19.76s4.2s– 1s– 14.6s===
[Eq. 102]
L
P
N
2
V
BST
2
V
MODE1
2V
BST
NV
MODE1
+
2
I
MODE1
TT F
sw1
2
-----------------------------------------------------------------------------------------------------------------------
=
[Eq. 103]
5.57
2
= 200V
2
20.95V
2 200V 5.57 20.95V+
2
213mA 35.05s70kHz
2
-------------------------------------------------------------------------------------------------------------------------------------------------------------
3543H=
I
PK1 FB
V
BST
T1
CH1
L
P
----------------
200V
5.3s
3543H
---------------------
299mA== =
[Eq. 104]
I
PK2 FB
V
BST
T1
CH2
L
P
----------------
200V
4.2s
3543H
---------------------
237mA== =
[Eq. 105]
I
MODE1 avg
I
PK1 FB
N
T2
CH1
2TT
----------------
299m
A 5.57
9.0s
2 35.05s
------------------------------
214mA== =
[Eq. 106]
I
MODE2 avg
I
PK2 FB
N
T2
CH2
2TT
----------------
237mA 5.57
14.7s
2 35.05s
------------------------------
277mA== =
[Eq. 107]