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

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

Specifications of MAX8655ETN+T

• 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)
G
mc
OUT
VCS
L
LOAD
OUT
= 600kHz
LOOP
= 1.8mΩ
= 1/(A
______________________________________________________________________________________
OUT
= 12
= 1.2V
= 4 x 100µF = 400µF
= V
( )
s
/V
K
= 20A
VCS
OUT
=
IN
S
(
( (
(
g
G s
⎡
⎢
⎣
1
1
1
1
mEA
= +
= +
=
= 1.2/12 = 0.1:
+
+
+
S
/I
+
Q
x R
1
1
1 18
( )
OUT(MAX)
s
s
s
.
C
R
L f
/
/
/
V
LOAD
120
1 25 0 56 10
L
×
(
(
(
=
=
OUT
×
) = 1/(12 x 0.0018) = 46.29S
.
2
2
2
Ro V
[
V
120 12 1 2 0 0018
π
π
⎛
⎜
⎜
⎝
π
S
π.(
1
SCOMP
×
( .
×
×
×
(
+
g
×
1
K
(
mc
×
f
f
f
(
pMOD
pEA
V
zMOD
π
+
S
IN
= 1.2/20 = 0.06Ω
⎡ ⎣
FB
.
Q f
s
.(
(
×
s
−
K
1
x
c S
/
−
)
G s
−
R
S
(
.
1
× ×
)
2
V
. )( .
LOAD
)
)
×
S
D
1
L f
× −
O
)
)
π
−
( )
(
+
)
6
(
×
1
)
×
1
−
×
)(
(
+
S
f
π
0 5
zEA
600000
R
s
s
.
D
. )
f
S
L
2
/
)
)
)
(
]
)
2
2
−
)
)
π
⎞
⎟
⎟
⎠
0 5 5
,
×
.
)
f
⎤ ⎦
p p dEA
⎤
⎥
⎦
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
C
f
C
f
pMOD
zMOD
G
46 29
C
C
F
MOD dc
G
= 44.7kΩ
.
=
=
MOD fc
=
2
=
2
π
×
2
(
zMOD
2
C
π
π
⎡
⎢
⎣
⎡
⎢
⎢ ⎢
⎣
2 400 10
π
×
1
2
2 0 56 10
π
C
F
×
×
( )
= 40.2kΩ
π
π
×
)
(
+
R
R
( .
= 5pF (not used)
× ×
0 9
f
= 470pF
=
R
pMOD
LOAD
C
( .
.
L f
0 56 10
g
C
1
x
=
×
×
C
> f
1
mc
x
S
C
G
=
=
f
1
1
−
zMOD
×
≤ 120kHz, select f
OUT
×
6
MOD dc
1
x
1
C
C
−
1 2
0 7
C
)( .
V
×
6
×
OUT
V
0 06
:
OUT
.
.
OUT
)(
⎡
⎢
⎣
f
FB
R
0 06
×
600000 400 10
pMOD
1
−
(
.
C
ESR
+
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
C
×
.
)
(
−
1
R
[
6
×
−
≤
×
1
(
×
×
LOAD
)
6
K
(
[
D
=
×
400 10
1 18 1 0 1 0 5
f
G
S
)
5
S
1
)( .
0 8
2 53
×
C
.
−
.
1
0 307
MOD fc
.
× −
3
0 5
(
×
1
1
40 2 10
= 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
=
3
⎤
⎥
⎥
⎦
483 9
=
.
= 8 18
884 2
=
)
2 53
=
.
.
.
.
5
kHz
pF
kHz
pF