Advanced Analog Technology, Inc.
AAT1102 (BIN2)
Inductor selection
V
IN
D
, where
D
is duty cycle
2
Lf
s
I
V
And
I
IN
=
o
,
D
=
1
−
IN
,
1
−
D
V
o
The inductor current rating must be greater than
I
L
(
peak
)
=
I
IN
+
Power Stage Transfer Functions
The duty to output voltage transfer function
T
p
is
:
(
s
+
w
)(
s
−
w
z
2
)
v
o
=
T
p
0 2
esr
2
d
s
+
2
ξ
w
n
s
+
w
n
−
r
c
1
,
w
esr
=
(
1
−
D
)(
R
L
+
r
c
)
Cr
c
T
p
(
s
)
=
I
L(peak)
.
Loop Compensation Design
Where
T
p
0
=
V
O
And
(
1
−
D
)
2
R
L
+
r
w
z
2
LC
(
R
L
+
r
c
)
2
C
[
r
(
R
L
+
r
c
)
+
R
L
r
c
(
1
−
D
)
]
+
L
ξ
=
,
2
2
LC
(
R
L
+
r
c
)
[
r
+
(
1
−
D
)
R
L
]
R
(
1
−
D
)
−
r
=
L
,
w
n
=
L
2
r
=
r
L
+
Dr
DS
+
(1
−
D
)
R
F
r
L
is the inductor equivalent series resistance,
r
c
is capacitor ESR,
R
L
is the converter load
resistance,
C
is output filter capacitor,
r
DS
is the
Fig.1. Closed-current loop for boost with PCM
transistor on-resistance, and
R
F
is the diode
forward resistance.
The duty to inductor current transfer function
T
pi
is:
T
pi
(
s
)
=
i
l
s
+
w
zi
=
T
pi
0 2
2
d
s
+
2
ξ
w
n
s
+
w
n
V
O
(
R
L
+
2
r
c
)
1
,
w
zi
=
C
(
R
L
/ 2
+
r
c
)
L
(
R
L
+
r
c
)
Where
T
pi
0
=
Fig.2. Block diagram of boost converter with
PCM
–
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–
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Advanced Analog Technology, Inc
.
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Page 10 of 18
V5.0
AAT [ ADVANCED ANALOG TECHNOLOGY, INC. ]
