Applications Information
The buck converters of the MAX20335 are optimized for
use with a tiny inductor and small ceramic capacitors. The
correct selection of external components ensures high
efficiency, low output ripple, and fast transient response.
Inductor Selection
A 2.2µH inductor is recommended for use with the
MAX20335 buck converters.
inductors for use depending on whether a given application
requires highest efficiency, or a compromise between
high efficiency and small size.
Output Capacitor Selection
The output capacitors of the MAX20335 buck converters
are required to keep the output voltage ripple small and
to ensure regulation loop stability. A 10µF output capacitor
with Buck_ISet[3:0] = 150mA and Buck_IAdptEnb = 0 is
suggested to cover all the possible output voltage/load
current cases. If a lower output cap are needed, please
for the minimum allowed capacitor size).
Ceramic capacitors are recommended due to their small
size and low ESR and care should be taken to ensure
that the selected capacitor maintains its capacitance
over temperature and voltage bias. Capacitors with X5R
or X7R temperature characteristics perform well in most
applications.
Input Capacitor Selection
The input capacitors of the buck converters reduce the
current peaks drawn from the battery or input power
source and reduces switching noise in the IC. The impedance
of the input capacitors at the switching frequency should
be kept very low. Ceramic capacitors are recommended
due to their small size and low ESR. Make sure the
capacitor maintains its capacitance over temperature and
DC bias. Capacitors with X5R or X7R temperature
characteristics perform well in most applications.
PCB Layout and Routing
High switching frequencies and large peak currents make
PCB layout a very important part of design. Good design
minimizes excessive EMI on the feedback paths and
voltage gradients in the ground plane, both of which can
result in instability or regulation errors. Connect the inductor,
input capacitor, and output capacitor as close together as
possible, and keep their traces short, direct, and wide.
Connect the two GND pins under the IC and directly to the
grounds of the input and output capacitors. Keep noisy
traces, such as the LX node, as short as possible.
*Minimum Output Capacitor Values are given for L = 2.2µH
Table 37. Output Capacitor Values*
Table 36. Suggested Inductors
MANUFACTURER
SERIES
INDUCTANCE
(µH)
DC RESISTANCE
(mΩ)
CURRENT
RATING (mA)
DIMENSIONS
L x W x H (mm)
NOTES
BOURNS
2.2
168
2200
2.0 x 1.6 x 1.0
Optimized for
highest efficiency
MURATA
MFD160810
2.2
310
1400
1.6 x 0.8 x 1.0
Optimized for
smallest size
BUCK_ISET[3:0]
OUTPUT VOLTAGE
(V)
OUTPUT CAPACITOR MINIMUM VALUES
(µF)
<150mA
>1.4V
2.2
<200mA
>1.2V
4.7
<175mA
>0.8
10
MAX20335
PMIC with Ultra-Low I
Q
Voltage Regulators and
Battery Chargers for Small Lithium Ion Systems
www.maximintegrated.com
Maxim Integrated
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