MAX8655ETN+ Maxim Integrated Products, MAX8655ETN+ Datasheet - Page 20

• Manufacturer Part Number: MAX8655ETN+
• Description: IC STEP-DN REG 25A 56-TQFN-EP
• Manufacturer: Maxim Integrated Products
• Type: Step-Down (Buck)r

Specifications of MAX8655ETN+

• Internal Switch(s): Yes
• Synchronous Rectifier: No
• Number Of Outputs: 1
• Voltage - Output: 0.7 ~ 5.5 V
• Current - Output: 25A
• Frequency - Switching: 200kHz ~ 1MHz
• Voltage - Input: 4.5 ~ 25 V
• Operating Temperature: -40°C ~ 85°C
• Mounting Type: Surface Mount
• Package / Case: 56-TQFN Exposed Pad
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Power - Output: -
• Lead Free Status / Rohs Status: Lead free / RoHS Compliant

Highly Integrated, 25A, Wide-Input,
Internal MOSFET, Step-Down Regulator
obtained phase margin. A phase margin of at least 45°
is recommended:
where the sampling effect quality factor:
Below is a numerical example to calculate R
values of the typical operating circuit of Figure 3:
A
L = 0.56µH
R
f
g
V
I
R
C
ESR = 2mΩ/4 = 0.5mΩ
D = V
20
S
OUT(MAX)
mc
OUT
VCS
L
LOAD
OUT
= 600kHz
= 1.8mΩ
G
= 1 / (A
______________________________________________________________________________________
LOOP
OUT
= 12
= 1.2V
= 4 x 100µF = 400µF
= V
/ V
K
= 20A
( )
OUT
s
S
VCS
IN
G s
=
= +
= +
=
S
(
(
g
(
1
1
1 18
= 1.2/12 = 0.1:
⎡
⎢
⎣
1
1
/ I
1
( )
Q
1
mEA
x R
.
+
+
+
OUT(MAX)
+
C
120
1 25 0 56 10
s
s
s
=
R
.
L
=
/
/
/
L f
) = 1 / (12 x 0.0018) = 46.29S
V
⎛
⎜
⎜
⎝
120 12 1 2 0 0018
LOAD
2
2
2
×
1
[
SCOMP
×
V
π
π
π
π.(
×
( .
Ro V
+
O
×
×
×
(
S
(
(
K
V
g
1
π
f
f
f
IN
pMOD
pEA
zMOD
×
.
S
mc
+
Q f
×
= 1.2 / 20 = 0.06Ω
.(
s
−
x
s
c S
−
1
[
FB
.
(
/
× ×
×
) (
−
V
K
2
1
. )( .
1
L f
× +
O
−
R
π
D
S
)
)
G s
+
6
)
LOAD
1
)
×
×
× −
S
×
)(
(
−
S
f
π
(
( )
600000
zEA
R
1
0 5
s
.
s
f
S
. )
L
2
/
)
2
D
2
)
]
π
)
)
⎞
⎟
⎟
⎠
)
,
×
−
)
f
0 5
pdEA
.
C
]
⎤
⎥
⎦
and C
×
)
×
C
8.18kHz << f
Since f
R
Select the nearest standard value: R
Select the nearest standard value: C
R7 = R
C12 = C
C11 = C
f
C
f
C
pMOD
zMOD
G
46 29
C
C
F
MOD dc
G
= 44.7kΩ
.
=
=
MOD fc
=
2
=
2
2
π
(
×
zMOD
2
π
C
π
⎡
⎢
⎣
2 400 10
⎡
⎢
⎢ ⎢
⎣
π
1
×
2
2 0 56 10
C
F
π
×
×
( )
= 40.2kΩ
π
π
×
(
)
+
R
R
( .
f
= 5pF (not used)
× ×
0 9
=
R
= 470pF
p MOD
LOAD
C
( .
.
L f
0 56 10
g
C
1
x
=
×
×
> f
C
1
mc
x
G
S
C
f
=
=
1
1
−
zMOD
×
≤ 120kHz, select f
OUT
×
1
6
MOD dc
1
x
C
C
−
1 2
0 7
)( .
V
×
C
6
×
OUT
V
0 06
:
OUT
OUT
.
.
)(
⎡
⎢
⎣
f
FB
0 06
R
×
600000 400 10
pMOD
1
−
(
.
ESR
C
×
+
6
)
×
=
×
×
)(
0 9
1
R
0 8
0 9
(
.
)
=
2
110 10
600000
.
×
L fs
.
LOAD
=
×
π ( .
)(
2
+
×
×
g
+
2
×
<<
f
π
[
π
pMOD
0 06
K
mEA
x
×
×
40 2 10
S
.
x
f
c
0 9
f
8181 40 2 10
× −
C
×
.
)
(
−
1
R
[
6
×
−
≤
×
1
(
×
×
LOAD
)
6
K
(
[
D
=
×
400 10
1 18 1 0 1 0 5
f
G
S
)
5
1
)( .
S
0 8
×
2 53
.
C
−
.
1
0 307
.
MOD fc
× −
0 5
( .
3
×
1
1
= 60kHz.
.
(
(
1 18 1 0 1 0 5
) (
(
1
.
]
C
C
×
⎤
⎥ =
⎦
×
−
−
(
6
( )
= 40.2kΩ:
884 2 10
= 470pF:
D
60000
x
)
8118
)
−
. )
×
)
)
0 0005
. )
.
−
−
.
3
0 5
−
x
)
.
.
=
=
.
]
]
)
⎤
⎥
⎦
=
0 345
483 9
3
⎤
⎥
⎥
⎦
=
.
= 8 18
884 2
=
)
2 53
=
.
.
.
.
5
kHz
kHz
pF
pF