Datasheet

ADP2164 Data Sheet
Rev. A | Page 16 of 20
APPLICATIONS INFORMATION
ADISIMPOWER DESIGN TOOL
The ADP2164 is supported by ADIsimPower design tool set.
ADIsimPower is a collection of tools that produce complete
power designs optimized for a specific design goal. The tools
enable the user to generate a full schematic, bill of materials,
and calculate performance in minutes. ADIsimPower can
optimize designs for cost, area, efficiency, and parts count
while taking into consideration the operating conditions and
limitations of the IC and all real external components. For
more information about ADIsimPower design tools, refer to
www.analog.com/ADIsimPower. The tool set is available from
this website, and users can also request an unpopulated board
through the tool.
The typical application circuit for the ADP2164 is shown in
Figure 38.
09944-042
ADP2164ACPZ
C
IN
47µF
X5R
10V
C
OUT1
47µF
X5R
6.3V
C
OUT2
100µF
X5R
6.3V
V
OUT
1.2V
4A
V
IN
3.3V
SYNC
TRK
FB
RT
SW
SW
SW
PVIN
GND PGND PGND PGND
L
0.8µH
R
TOP
10kΩ
R
BOT
10kΩ
L: MSS1048-801NL COILCRAFT
C
IN
: C3225X5R1A476M TDK
C
OUT1
: C3225X5R0J476M TDK
C
OUT2
: C3225X5R0J107M TDK
12
11
10
94
3
2
1
5 6 7 8
PGOOD
C1
0.1µF
EN
R1
10Ω
R2
10kΩ
PVIN
16 15
VIN
14
13
Figure 38. Typical Application Circuit
OUTPUT VOLTAGE SELECTION
The output voltage of the adjustable version of the ADP2164 is
set by an external resistive voltage divider using the following
equation:








+×=
BOT
TOP
OUT
R
R
V 16.0
To limit output voltage accuracy degradation due to FB bias
current (0.1 µA maximum) to less than 0.5% (maximum),
ensure that R
BOT
is less than 30 kΩ.
INDUCTOR SELECTION
The inductor value is determined by the operating frequency,
input voltage, output voltage, and ripple current. A small inductor
value provides larger inductor current ripple and fast transient
response but degrades efficiency; a large inductor value provides
small inductor current ripple and good efficiency but slows
transient response. For a reasonable trade-off between transient
response and efficiency, the inductor current ripple, ΔI
L
, is typically
set to one-third the maximum load current. The inductor value
is calculated using the following equation:
( )
S
L
OUT
IN
fI
DVV
L
×∆
×−
=
where:
V
IN
is the input voltage.
V
OUT
is the output voltage.
ΔI
L
is the inductor current ripple.
f
S
is the switching frequency.
D is the duty cycle (V
OUT
/V
IN
).
The ADP2164 uses slope compensation in the current control
loop to prevent subharmonic oscillations when the duty cycle
is larger than 50%. The internal slope compensation limits the
minimum inductor value.
The negative current limit (−1.3 A) also limits the minimum
inductor value. The inductor current ripple (ΔI
L
) calculated by
the selected inductor should not exceed 2.6 A.
The peak inductor current should be kept below the peak current
limit threshold and is calculated using the following equation:
2
L
OPEAK
I
II
∆
+=
Ensure that the rms current of the selected inductor is greater
than the maximum load current and that its saturation current
is greater than the peak current limit of the converter.
OUTPUT CAPACITOR SELECTION
The output capacitor value is determined by the output voltage
ripple, load step transient, and loop stability. The output ripple
is determined by the ESR and the capacitance.








××
+×∆=∆
S
OUT
L
OUT
fC
ESRIV
8
1
The load step transient response depends on the inductor, the
output capacitor, and the current control loop.
The ADP2164 has integrated loop compensation for simple
power design. Table 5 and Table 6 show the recommended
values for inductors and capacitors for the ADP2164 based
on the input and output voltages for the part. X5R or X7R
dielectric ceramic capacitors are highly recommended.
Table 5. Recommended L and C
OUT
Values at f
S
= 1.2 MHz
V
IN
(V) V
OUT
(V) L (µH) C
OUT
(µF)
3.3 1.0 0.8 100 + 100
3.3 1.2 0.8 100 + 47
3.3 1.5 1 100 + 47
3.3 1.8 1 100
3.3 2.5 1 47
5 1.0 0.8 100 + 100
5 1.2 0.8 100 + 47
5 1.5 1 100 + 47
5
1.8
1
100
5 2.5 1 47
5 3.3 1 47