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ADP5024CP-EVALZ
ADP5024
Data Sheet
Rev. E | Page 22 of 28
The peak-to-peak output voltage ripple for the selected output
capacitor and inductor values is calculated using the following
equation:
(
)
OUT
SW
IN
OUT
SW
RIPPLE
RIPPLE
C
L
f
V
C
f
I
V
×
×
×
π
≈
×
×
=
2
2
8
Capacitors with lower equivalent series resistance (ESR) are
preferred to guarantee low output voltage ripple, as shown in
the following equation:
RIPPLE
RIPPLE
COUT
I
V
ESR
≤
The effective capacitance needed for stability, which includes
temperature and dc bias effects, is a minimum of 7 µF and a
maximum of 40 µF.
The buck regulators require 10 µF output capacitors to guarantee
The buck regulators require 10 µF output capacitors to guarantee
stability and response to rapid load variations and to transition
into and out of the PWM/PSM modes. A list of suggested capaci-
into and out of the PWM/PSM modes. A list of suggested capaci-
tors is shown in Table 10. In certain applications where one or
both buck regulator powers a processor, the operating state is
known because it is controlled by software. In this condition,
the processor can drive the MODE pin according to the operating
the processor can drive the MODE pin according to the operating
state; consequently, it is possible to reduce the output capacitor
from 10 µF to 4.7 µF because the regulator does not expect a
large load variation when working in PSM mode (see Figure 50).
Input Capacitor
Higher value input capacitors help to reduce the input voltage
ripple and improve transient response. Maximum input
ripple and improve transient response. Maximum input
capacitor current is calculated using the following equation:
IN
OUT
IN
OUT
MAX
LOAD
CIN
V
V
V
V
I
I
)
(
)
(
−
≥
To minimize supply noise, place the input capacitor as close as
possible to the VINx pin of the buck. As with the output capa-
citor, a low ESR capacitor is recommended.
A 4.7 µF capacitor is recommended for a typical application;
A 4.7 µF capacitor is recommended for a typical application;
depending on the application, a smaller or larger output capacitor
may be chosen. A list of suggested 4.7 µF capacitors is shown in
Table 11. The effective capacitance needed for stability, which
Table 11. The effective capacitance needed for stability, which
includes temperature and dc bias effects, is a minimum of 3 µF
and a maximum of 10 µF.
Table 10. Suggested 10 μF Capacitors
Vendor
Type
Model
Case
Size
Voltage
Rating
Rating
(V)
Murata
X5R
GRM188R60J106
0603
6.3
TDK
X5R
C1608JB0J106K
0603
6.3
Panasonic
X5R
ECJ1VB0J106M
0603
6.3
Table 11. Suggested 4.7 μF Capacitors
Vendor
Type
Model
Case
Size
Voltage
Rating
Rating
(V)
Murata
X5R
GRM188R60J475ME19D
0402
6.3
Taiyo Yuden X5R
JMK107BJ475
0402
6.3
Panasonic
X5R
ECJ-0EB0J475M
0402
6.3
Table 12. Suggested 1.0 μF Capacitors
Vendor
Type
Model
Case
Size
Voltage
Rating
Rating
(V)
Murata
X5R
GRM155B30J105K
0402
6.3
TDK
X5R
C1005JB0J105KT
0402
6.3
Panasonic
X5R
ECJ0EB0J105K
0402
6.3
Taiyo
Yuden
Yuden
X5R
LMK105BJ105MV-F
0402
10.0
VIN1
VIN3
EN1
PWM
PSM/PWM
2.3V TO
5.5V
SW1
FB1
R2
R1
VOUT1
PGND1
MODE
C5
10µF
10µF
V
OUT1
AT
1200mA
L1 1µH
EN1
BUCK1
MODE
C3
1µF
C2
4.7µF
C1
4.7µF
AVIN
C
AVIN
0.1µF
VIN2
EN2
AGND
EN2
BUCK2
MODE
EN3
1.7V TO
5.5V
ON
OFF
ON
OFF
EN3
LDO
(ANALOG)
ADP5024
HOUSEKEEPING
SW2
FB2
R4
R3
VOUT2
PGND2
C6
10µF
10µF
V
OUT2
AT
1200mA
L2 1µH
FB3
R6
R5
VOUT3
C7
1µF
1µF
V
OUT3
AT
300mA
09888-
050
Figure 50. Processor System Power Management with PSM/PWM Control