ADP2380-EVALZ Analog Devices, ADP2380-EVALZ Datasheet - Page 21

• Manufacturer Part Number: ADP2380-EVALZ
• Description: Power Management IC Development Tools 20V 4A Evaluation Board
• Manufacturer: Analog Devices
• Type: DC/DC Converters, Regulators & Controllersr
• Series: ADP2380r

Specifications of ADP2380-EVALZ

• Rohs: yes
• Tool Is For Evaluation Of: ADP2380
• Input Voltage: 4.5 V to 20 V
• Factory Pack Quantity: 1

Data Sheet
LOW-SIDE MOSFET SELECTION
A low R
solution. The breakdown voltage of the MOSFET must be
higher than 1.2 × V
1.2 × I
It is recommended to use a 30 V, N-channel MOSFET, such as
the FDS6298 from Fairchild. The R
driver voltage is 9.4 mΩ, and the total gate charge at 5 V is 10 nC.
COMPENSATION COMPONENTS
For better load transient and stability performance, set the cross
frequency, f
where:
R
C
C
A =
B =
C
C
R
C
C
CP
LIMIT
C
C
CP
DSON
=
=
_
_
=
(1 + 470 µS × 40 MΩ) = 3.4 × 10
2.26 × 10
_
1
EA
EA
R
r
.
EA
2
2
(
3 (
0
+
R
TOP
R
R
C
N-channel MOSFET is chosen as a high efficiency
=
×
(
=
×
, at f
3 .
TOP
C
=
ESR
g
+
π
π
B
B
m
CP
V
0
V/
+
(
R
R
6 .
R
C
B
×
(
×
×
REF
SW
+
×
ESR
R
A
C
BOT
+
V
4
−6
C
3
g
+
R
C
/10. In this case, f
R
V
BOT
IN
OUT
+
_
3 .
r
C
m
A
C
C
0
OUT
×
)
EA
R
, and the drain current must be larger than
×
R
C
r
C
×
−
V
C
0
+
g
C
)
470
(
C
C
C
)
×
1
m
C
27
(
. 0
×
=
=
B
C
OUT
+
C
C
×
002
2
)(
1 .
1
C
OUT
. 0
+
g
μS
A
×
r
r
+
CP
kΩ
002
m
0
0
40
VI
R
32
R
=
Ω
+
×
470
C
×
×
C
C
MΩ
)
8
DSON
C
r
A
μF
Ω
27
10µF
f
0
C
7 .
25V
×
C
)
C
C
μS
)
V
IN
)(
×
1 .
C
C
2
IN
×
A/V
=
×
of the FDS6298 at a 4.5 V
r
= 1/500 kHz = 50 kHz.
=
= 12V
CP
×
2
0
kΩ
×
50
10
10
(
100kΩ
R
. 4
×
+
32
3 (
22nF
OSC
C
7
kHz
73
SS
32
kΩ
kΩ
4 .
A
μF
)
pF
×
μF
×
+
1
2
3
4
5
6
7
8
10
= 27.1 kΩ
= 1.96 nF
. 2
. 2
+
PVIN
PVIN
UVLO
PGOOD
RT
SYNC
EN/SS
COMP
7
= 4.73 pF
21
21
. 1
1000pF
C
+
96
C_EA
kΩ
kΩ
40
Figure 36. Design Example Schematic
ADP2380
C
nF)
2.2pF
CP_EA
MΩ
×
49.9kΩ
R
C_EA
Rev. 0 | Page 21 of 28
=
PGND
VREG
GND
BST
SW
SW
LD
FB
16
15
14
13
12
11
10
9
C
C
0.1µF
1µF
VREG
BST
This results in the following:
Choose the standard values for R
and C
Figure 35 shows the Bode plot at 4 A. The cross frequency is
43 kHz, and the phase margin is 59°.
SOFT START TIME PROGRAM
The soft start feature allows the output voltage to ramp up in a
controlled manner, eliminating output voltage overshoot during
soft start and limiting the inrush current. Set the soft start time
to 4 ms.
Choose a standard component value, C
INPUT CAPACITOR SELECTION
A minimum 10 μF ceramic capacitor must be placed near the
PVIN pin. In this application, one 10 μF, X5R, 25 V ceramic
capacitor is recommended.
M1
FDS6298
4.7µH
–12
–24
–36
–48
–60
R
C
C
C
L1
60
48
36
24
12
CP_EA
C_EA
0
C_EA
CP_EA
SS
1k
=
= 52.3 kΩ.
= 1055 pF.
= 2.2 pF.
t
= 2.45 pF.
SS
R
10kΩ
1%
R
2.21kΩ
1%
TOP
BOT
_
C
47µF
6.3V
EXT
OUT1
0
V
6 .
OUT
×
10k
V
= 3.3V
I
Figure 35. Bode Plot at 4 A
C
47µF
6.3V
SS
OUT2
_
FREQUENCY (Hz)
UP
=
4
C_EA
ms
100k
0
= 49.9 kΩ, C
×
6 .
3
V
SS
2 .
= 22 nF.
μA
= 21.3 nF
C_EA
1M
ADP2380
= 1000 pF,
180
144
108
72
36
0
–36
–72
–108
–144
–180