AS1340
Datasheet - Application Information
Capacitor Selection
A 4.7µF capacitor is recommended for CIN as well as a 2µF for COUT. Small-sized ceramic capacitors are recom-
mended. X5R and X7R ceramic capacitors are recommend as they retain capacitance over wide ranges of voltages
and temperatures.
Output Capacitor Selection
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. 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.
X5R and X7R dielectric materials are recommended due to their ability to maintain capacitance over wide voltage and
temperature ranges.
Table 5. Recommended Output Capacitor
Part Number
C
TC Code Rated Voltage Dimensions (L/W/T)
Manufacturer
Murata
www.murata.com
GRM31MR71H105KA88
GRM32ER71H475KA88
C1206C105K5RAC
C1206C225K5RAC
1µF
X7R
X7R
X7R
X7R
50V
50V
50V
50V
C1206
C1210
C1206
C1210
4.7µF
1µF
Kemet
www.kemet.com
2.2µF
AVX
www.avx.com
1206C105KAT2A
1µF
X7R
50V
C1206
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 6. Recommended Input Capacitor
Part Number
C
TC Code Rated Voltage Dimensions (L/W/T)
Manufacturer
Murata
www.murata.com
GRM21BR71C105KA01
GRM21BR61C225KA88
GRM32DR71C106KA01
1µF
X7R
X7R
X7R
16V
16V
16V
C0805
C0805
C1210
2.2µF
10µF
Diode Selection
A Schottky diode must be used to carry the output current for the time it takes the PMOS synchronous rectifier to
switch on.
Note: Do not use ordinary rectifier diodes, since the slow recovery times will compromise efficiency.
Table 7. Recommended Diodes
Part Number
Reverse Voltage Forward Current
Package
Manufacturer
Philips
www.nxp.com
PMEG4010BEA
40V
1A
SOD123
MCC
www.mccsemi.com
MBR0540
MBR0560
40V
60V
500mA
500mA
SOD123
SOD123
Thermal Protection
To protect the device from short circuit or excessive power dissipation of the auxiliary NPNs, the integrated thermal
protection switches off the device when the junction temperature (TJ) reaches 145ºC (typ). When TJ decreases to
approximately 125ºC, the device will resume normal operation. If the thermal overload condition is not corrected, the
device will switch on and off while maintaining TJ within the range between 125 and 145ºC.
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