AS1329
Data Sheet
- Application Information
Figure 20. Efficiency Comparison of Different Inductors, V
IN
= 1.5V, V
OUT
= 3.3V
90
85
80
75
92
90
88
Efficiency (%)
Efficiency (%)
70
65
60
55
50
45
40
0.1
1
10
10uH - Coi l cr af t (M OS6020-103M L)
10uH - Sumi da(CDRH4D18-100)
6. 8uH - Sumi da(CDRH4D18-6R8)
6. 8uH - Sumi da(CR43-6R8)
4. 7uH - Coi l cr af t (M OS6020-472M L)
4. 7 uH - Sumi da(CDRH4D18-4R7)
3. 3 uH - Coi l cr af t (M OS6020-332M L)
86
84
82
10uH - Coi l cr af t (M OS6020-103M L)
80
78
76
10uH - Sumi da(CDRH4D18-100)
6. 8uH - Sumi da(CDRH4D18-6R8)
6. 8uH - Sumi da(CR43-6R8)
4. 7uH - Coi l c r af t (M OS6020-472M L)
4. 7 uH - Sumi da(CDRH4D18-4R7)
3. 3 uH - Coi l c r af t (M OS6020-332M L)
S
i
8
Output Current (mA)
10
Output Current (mA)
100
Output Capacitor Selection
Low ESR capacitors should be used to minimize V
OUT
ripple. Multi-layer ceramic capacitors are recommended since
they have extremely low ESR and are available in small footprints. A 2.2 to 10µF output capacitor is sufficient for most
applications. Larger values up to 22µF may be used to obtain extremely low output voltage ripple and improve tran-
sient response.
An additional phase lead capacitor may be required with output capacitors larger than 10µF to maintain acceptable
phase margin. X5R and X7R dielectric materials are recommended due to their ability to maintain capacitance over
wide voltage and temperature ranges.
Table 6. Recommended Output Capacitor
Part Number
JMK212BJ226MG-T
Input Capacitor Selection
Low ESR input capacitors reduce input switching noise and reduce the peak current drawn from the battery. Ceramic
capacitors are recommended for input decoupling and should be located as close to the device as is practical. A 4.7µF
input capacitor is sufficient for most applications. Larger values may be used without limitations.
Table 7. Recommended Input Capacitor
Part Number
C
TC Code Rated Voltage Dimensions (L/W/T)
X7R
6.3V
3.2x1.6x1.6mm
Manufacturer
Murata
C
22µF ±20%
TC Code Rated Voltage
X5R
6.3V
Dimensions (L/W/T)
2x1.3x1.3mm
Manufacturer
Taiyo Yuden
GRM31CR70J106KA01L 10µF ±10%
Diode Selection
A Schottky diode should be used to carry the output current for the time it takes the PMOS synchronous rectifier to
switch on. For V
OUT
< 4.5V a Schottky diode is optional, although using one will increase device efficiency by 2 to 3%.
Note:
Do not use ordinary rectifier diodes, since the slow recovery times will compromise efficiency.
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