ADP5040 Analog Devices, ADP5040 Datasheet - Page 30

• Manufacturer Part Number: ADP5040
• Description: Micro PMU with 1.2 A Buck Regulator and Two 300 mA LDOs
• Manufacturer: Analog Devices

ADP5040
Capacitors with lower equivalent series resistance (ESR) are
preferred to guarantee low output voltage ripple, as shown in
the following equation:
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.
Table 9. Suggested 10 μF Capacitors
Vendor
Murata
Taiyo Yuden
TDK
Panasonic
The buck regulator requires 10 µF output capacitors to guaran-
tee stability and response to rapid load variations and to transition
in and out the PWM/PSM modes. In certain applications, where
the 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
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 106).
Input Capacitor
A higher value input capacitor helps to reduce the input voltage
ripple and improve transient response. Maximum input
capacitor current is calculated using the following equation:
2.3V TO 5.5V
Figure 106. Processor System Power Management with PSM/PWM Control
V
IN
ESR
I
CIN
COUT
≥
I
R
30Ω
LOAD
FLT
≤
Type
X5R
X5R
X5R
X5R
V
C3
1µF
C2
1µF
I
C1
10µF
(
AVIN
VIN1
VIN2
VIN3
MAX
RIPPLE
RIPPLE
)
ADP5040
MICRO PMU
V
Model
GRM188R60J106
JMK107BJ106MA-T
C1608JB0J106K
ECJ1VB0J106M
OUT
(
V
V
IN
IN
SW
VOUT1
FB1
VOUT2
FB2
FB3
VOUT3
−
MODE
ENx
V
R1
R2
R3
R4
OUT
1µH
R5
R6
L1
PGND
3
)
C5
2.2µF
C4
4.7µF
C6
2.2µF
Case
Size
0603
0603
0603
0603
PROCESSOR
SUBSYSTEM
VCORE
VDDIO
GPIO1
GPIO[x:y]
VANALOG
ANALOG
Voltage
Rating
(V)
6.3
6.3
6.3
6.3
Rev. 0 | Page 30 of 40
To minimize supply noise, place the input capacitor as close
to the VIN pin of the buck as possible. As with the output
capacitor, a low ESR capacitor is recommended.
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. A list of suggested capacitors is shown in
Table 10.
Table 10. Suggested 4.7 μF Capacitors
Vendor
Murata
Taiyo Yuden
Panasonic
LDO EXTERNAL COMPONENT SELECTION
Feedback Resistors
Referring to Figure 103 the maximum value of Rb is not to
exceed 200 kΩ.
Output Capacitor
The
space-saving ceramic capacitors, but they function with most
commonly used capacitors as long as care is taken with the ESR
value. The ESR of the output capacitor affects stability of the
LDO control loop. A minimum of 0.70 µF capacitance with an
ESR of 1 Ω or less is recommended to ensure stability of the
LDO. Transient response to changes in load current is also
affected by output capacitance. Using a larger value of output
capacitance improves the transient response of the LDO to large
changes in load current.
When operating at output currents higher than 200 mA a
minimum of 2.2 µF capacitance with an ESR of 1 Ω or less is
recommended to ensure stability of the LDO.
Table 11. Suggested 2.2 μF Capacitors
Vendor
Murata
TDK
Panasonic
Taiyo Yuden
Input Bypass Capacitor
Connecting 1 µF capacitors from VIN2 and VIN3 to ground
reduces the circuit sensitivity to printed circuit board (PCB)
layout, especially when long input traces or high source impedance
is encountered. If greater than 1 µF of output capacitance is
required, increase the input capacitor to match it.
ADP5040
Type
X5R
X5R
X5R
LDOs are designed for operation with small,
Type
X5R
X5R
X5R
X5R
Model
GRM188R60J475ME19D
JMK107BJ475
ECJ-0EB0J475M
Model
GRM188B31A225K
C1608JB0J225KT
ECJ1VB0J225K
JMK107BJ225KK-T
Case
Size
0402
0402
0402
0402
Data Sheet
Case
Size
0603
0603
0402
Voltage
Rating
(V)
6.3
6.3
6.3
Voltage
Rating
(V)
10.0
6.3
6.3
6.3