AS1340 データシートの表示（PDF） - austriamicrosystems AG
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AS1340 Datasheet PDF : 17 Pages
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AS1340
Datasheet - Application Information
9.7 Capacitor Selection
A 4.7µF capacitor is recommended for CIN as well as a 2µF for COUT. Small-sized ceramic capacitors are recommended. X5R and X7R
ceramic capacitors are recommend as they retain capacitance over wide ranges of voltages and temperatures.
9.7.1 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 transient 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
GRM31MR71H105KA88
1µF
GRM32ER71H475KA88
4.7µF
C1206C105K5RAC
1µF
C1206C225K5RAC
2.2µF
1206C105KAT2A
1µF
TC Code
X7R
X7R
X7R
X7R
X7R
Rated Voltage
50V
50V
50V
50V
50V
Dimensions (L/W/T)
C1206
C1210
C1206
C1210
C1206
Manufacturer
Murata
www.murata.com
Kemet
www.kemet.com
AVX
www.avx.com
9.7.2 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
GRM21BR71C105KA01
1µF
GRM21BR61C225KA88
2.2µF
GRM32DR71C106KA01
10µF
TC Code
X7R
X7R
X7R
Rated Voltage
16V
16V
16V
Dimensions (L/W/T)
C0805
C0805
C1210
Manufacturer
Murata
www.murata.com
9.7.3 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
PMEG4010BEA
MBR0540
MBR0560
Reverse Voltage
40V
40V
60V
Forward Current
1A
500mA
500mA
Package
SOD123
SOD123
SOD123
Manufacturer
Philips
www.nxp.com
MCC
www.mccsemi.com
9.8 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
125ºC and 145ºC.
www.ams.com/DC-DC_Step-Up/AS1340
Revision 1.20
13 - 17
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