ADP3168JRUZ-REEL AD [Analog Devices], ADP3168JRUZ-REEL Datasheet - Page 20

• Manufacturer Part Number: ADP3168JRUZ-REEL
• Description: 6-Bit, Programmable 2-, 3-, 4-Phase Synchronous Buck Controller
• Manufacturer: AD [Analog Devices]

ADP3168
The first step is to compute the time constants for all of the poles and zeros in the system:
where, for the ADP3168, R' is the PCB resistance from the bulk capacitors to the ceramics and where R
ON resistance per phase. For this example, A
L
The compensation values can be solved using the following:
Choosing the closest standard values for the components yields
X
is 375 pH for the eight Al-Poly capacitors.
T
T
T
T
C
CA
C
C
C
R
R
R
B
C
D
A
E
E
A
A
B
FB
A
=
=
=
=
=
=
=
=
=
=
=
=
C
(
V
3
C
390
n
C
R
n
3
T
T
R
37
RT
T
×
X
R
C
X
B
×
B
×
X
×
R
A
D
A
1
×
E
1
9 .
×
+
×
R
R
=
=
3 .
pF
3 .
=
(
×
O
C
O
(
⎛
⎜
⎜
⎝
R
R
V
m
. 1
371
R
. 1
m
6
,
L
16
m
VID
X
×
R
×
O
'
Ω
O
−
2 .
33
521
R
97
Ω
B
Ω
−
T
−
R
×
7 .
A
A
−
×
µs
+
pF
A
×
O
k
D
C
R
A
×
µs
=
R
. 1
k
5
2
Ω
ns
)
D
R
'
Z
×
. 4
Ω
)
'
16
×
33
×
×
)
=
E
+
×
×
+
=
79
R
C
16
4
9 .
=
f
k
. 1
DS
R
R
C
L
R
2 .
SW
X
Ω
31
O
µs
7 .
DS
k
X
O
2
48
Z
=
Ω,
+
m
×
2 .
×
k
⎞
⎟
⎟
⎠
Ω
(
=
nF
R
1
Ω
R
C
pF
R
=
0 .
L
+
371
V
O
B
O
×
1
R
. 0
DID
m
=
=
6 .
−
X
V
63
Ω
pF
1
RT
R
. 6
m
5 .
+
'
V
56
1
Ω
=
0
+
nF
5 .
×
6 .
×
. 6
mF
D
1
2
V
,
⎛
⎜ ⎜
⎝
. 0
56
5 .
is 5, V
m
C
600
×
n
63
Ω
×
FB
. 6
V
L
mF
×
−
56
(
V
1
nH
×
=
×
C
1
3 .
RT
×
(
+
3 .
37
33
X
mF
1
m
equals 0.63 V, R' is approximately 0.6 mΩ (assuming a 4-layer motherboard), and
=
(
−
2
1
m
×
9 .
Ω
pF
3 .
(30)
(31)
(32)
(33)
×
3
2
n
×
Ω
R
5
−
m
×
×
600
×
m
230
O
×
)
Rev. B | Page 20 of 24
Ω
0
×
. 6
267
Ω
D
×
4
6 .
. 6
56
2 .
V
−
)
nH
µF
m
×
56
VID
0
m
kHz
mF
Ω
V
6 .
×
Ω
×
mF
)
RT
m
(
+
(
1
1
×
⎞
⎟ ⎟
⎠
Ω
3 .
230
−
1
=
=
)
3 .
. 0
m
. 1
Figure 13 shows the typical transient response using the
compensation values.
+
6
375
Ω
m
97
2 .
µF
375
1
)
Ω
3 .
2
µs
µs
×
)
×
m
×
1
pH
1
Ω
3 .
. 0
Figure 13. Typical Transient Response for Design Example
5 .
63
m
×
V
Ω
1
V
3 .
=
37
m
521
1
Ω
9 .
0 .
−
m
m
ns
0
Ω
Ω
6 .
m
Ω
DS
=
is the total low side MOSFET
. 4
79
µs
(25)
(26)
(27)
(28)
(29)