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Revision 1.09
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AS1334
Datasheet - Application Information
9 Application Information
9.1 Inductor Selection
For the external inductor, a 3.3μH inductor is recommended. Mnimuminductor size is dependant on the desired efficiency and output current.
Inductors with low core losses and small DCR at 2MHz are recommended.
9.2 Capacitor Selection
A 10μF capacitor is recommended for C
IN
as well as a 10μF for C
OUT
. Small-sized X5R or X7R ceramc capacitors are recommended as they
retain capacitance over wide ranges of voltages and temperatures.
9.2.1 Input and Output Capacitor Selection
Low ESR input capacitors reduce input switching noise and reduce the peak current drawn fromthe battery. Also low ESR capacitors should be
used to mnimze V
OUT
ripple. Multi-layer ceramc capacitors are recommended since they have extremely low ESR and are available in small
footprints.
For input decoupling the ceramc capacitor should be located as close to the device as practical. A 4.7μF input capacitor is sufficient for most
applications. Larger values may be used without limtations.
A 2.2μF to 10μF output ceramc capacitor is sufficient for most applications. Larger values up to 22μF may be used to obtain extremely low out-
put voltage ripple and improve transient response.
9.3 EN Pin Control
Drive the EN pin using the systemcontroller to turn the AS1334 ON and OFF. Use a comparator, Schmdt trigger or logic gate to drive the EN pin.
Set EN high (>1.2V) for normal operation and low (<0.5V) for a 0.01μA (typ) shutdown mode. Set EN low to turn off the AS1334 during power-up
and under voltage conditions when the power supply is less than the 2.7V mnimumoperating voltage. The part is out of regulation when the
input voltage is less than 2.7V.
Table 5. Recommended Inductor
Part Number
LPS4018-222ML_
LPS4018-332ML_
LPS4018-472ML_
L
DCR
0.070Ω
0.080Ω
0.125Ω
Current Rating
2.9A
2.4A
1.9A
Dimensions (L/W/T)
3.9x3.9x1.7mm
3.9x3.9x1.7mm
3.9x3.9x1.7mm
Manufacturer
2.2μH
3.3μH
4.7μH
Coilcraft
wwwcoilcraft.com
Table 6. Recommended Input and Output Capacitor
Part Number
GRM188R60J475KE19
GRM219R60J475KE19
GRM21BR61C475KA88
GRM31CR71E475KA88
GRM188R60J106ME47
GRM21BR60J106KE19
GRM21BR61A106KE19
GRM32DR71C106KA01
GRM21BR60J226ME39
GRM32ER71A226KE20
C
TC Code
X5R
X5R
X5R
X7R
X5R
X5R
X5R
X7R
X5R
X7R
Rated Voltage
6.3V
6.3V
16V
25V
6.3V
6.3V
10V
16V
6.3V
10V
Dimensions (L/W/T)
0603
0805
0805
1206
0603
0805
0805
1210
0805
1210
Manufacturer
Murata
4.7μF