AS1346-49
Datasheet - Application Information
9 Application Information
9.1 Component Selection
Only three power components are required to complete the design of the buck converter. For the adjustable LBI two external resistors are
needed.
9.2 Inductor Selection
For the external inductor, a 3.3μH inductor is recommended. Minimum inductor size is dependant on the desired efficiency and output current.
Inductors with low core losses and small DCR at 2MHz are recommended.
Table 5. Recommended Inductor
L
DCR
Current Rating
3.3μH
m
IMAX
Calculation of IMAX:
IOUT 1 V OUT 1 + IOUT 2 V OUT 2
IMAX = -------------------------------------------------------------------------------------
0 7 V IN
(EQ 2)
9.3 Capacitor Selection
A 10μF capacitor is recommended for CIN as well as a 10μF for COUT. Small-sized X5R or X7R ceramic capacitors are recommended as they
retain capacitance over wide ranges of voltages and temperatures.
9.3.1 Input and Output Capacitor Selection
Low ESR input capacitors reduce input switching noise and reduce the peak current drawn from the battery. Also low ESR capacitors should be
used to minimize VOUT ripple. Multi-layer ceramic capacitors are recommended since they have extremely low ESR and are available in small
footprints.
For input decoupling the ceramic capacitor should be located as close to the device as practical. A 22μF input capacitor is sufficient for most
applications. Larger values may be used without limitations.
A 2.2μF to 10μF output ceramic capacitor is sufficient for most applications. Larger values up to 22μF may be used to obtain extremely low
output voltage ripple and improve transient response.
Table 6. Recommended Input and Output Capacitor
C
TC Code
X5R
Rated Voltage
6.3V
CIN
10 - 47μF
COUT1, COUT2 2.2 - 10μF
X7R
25V
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