Datasheet LTC3429, LTC3429B (Analog Devices) - 9
| Fabricante | Analog Devices |
| Descripción | 600mA, 500kHz Micropower Synchronous Boost Converter with Output Disconnect |
| Páginas / Página | 12 / 9 — APPLICATIO S I FOR ATIO. Output and Input Capacitor Selection. Table 1. … |
| Formato / tamaño de archivo | PDF / 204 Kb |
| Idioma del documento | Inglés |
APPLICATIO S I FOR ATIO. Output and Input Capacitor Selection. Table 1. Recommended Inductors. MAX. DCR. HEIGHT. PART. (mm). VENDOR
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LTC3429/LTC3429B
U U W U APPLICATIO S I FOR ATIO
The inductor current ripple is typically set for 20% to 40%
Output and Input Capacitor Selection
of the maximum inductor current (IP). High frequency Low ESR (equivalent series resistance) capacitors should ferrite core inductor materials reduce frequency be used to minimize the output voltage ripple. Multilayer dependent power losses compared to cheaper powdered ceramic capacitors are an excellent choice as they have iron types, improving efficiency. The inductor should have extremely low ESR and are available in small footprints. A low ESR (series resistance of the windings) to reduce the 4.7µF to 15µF output capacitor is sufficient for most I2R power losses, and must be able to handle the peak applications. Larger values up to 22µF may be used to inductor current without saturating. Molded chokes and obtain extremely low output voltage ripple and improve some chip inductors usually do not have enough core to transient response. An additional phase lead capacitor support the peak inductor currents of 850mA seen on the may be required with output capacitors larger than 10µF LTC3429/LTC3429B. To minimize radiated noise, use a to maintain acceptable phase margin. X5R and X7R toroid, pot core or shielded bobbin inductor. See Table 1 dielectric materials are preferred for their ability to main- for some suggested components and suppliers. tain capacitance over wide voltage and temperature ranges.
Table 1. Recommended Inductors
Low ESR input capacitors reduce input switching noise
MAX
and reduce the peak current drawn from the battery. It
L DCR HEIGHT
follows that ceramic capacitors are also a good choice for
PART (
µ
H) m
Ω
(mm) VENDOR
input decoupling and should be located as close as pos- CDRH5D18-4R1 4.1 57 2.0 Sumida CDRH5D18-100 10 124 2.0 www.sumida.com sible to the device. A 10µF input capacitor is sufficient for CDRH3D16-4R7 4.7 105 1.8 virtually any application. Larger values may be used with- CDRH3D16-6R8 170 1.8 out limitations. Table 2 shows a list of several ceramic CR43-4R7 4.7 109 3.5 CR43-100 10 182 3.5 capacitor manufacturers. Consult the manufacturers di- CMD4D06-4R7MC 4.7 216 0.8 rectly for detailed information on their entire selection of CMD4D06-3R3MC 3.3 174 0.8 ceramic capacitors. DS1608-472 4.7 60 2.9 Coilcraft
Table 2. Capacitor Vendor Information
DS1608-103 10 75 2.9 www.coilcraft.com DO1608C-472 4.7 90 2.9
SUPPLIER WEBSITE
D52LC-4R7M 4.7 84 2.0 Toko AVX www.avxcorp.com D52LC-100M 10 137 2.0 www.tokoam.com Murata www.murata.com LQH32CN4R7M24 4.7 195 2.2 Murata Taiyo Yuden www.t-yuden.com www.murata.com 3429fa 9
U U W U APPLICATIO S I FOR ATIO
The inductor current ripple is typically set for 20% to 40%
Output and Input Capacitor Selection
of the maximum inductor current (IP). High frequency Low ESR (equivalent series resistance) capacitors should ferrite core inductor materials reduce frequency be used to minimize the output voltage ripple. Multilayer dependent power losses compared to cheaper powdered ceramic capacitors are an excellent choice as they have iron types, improving efficiency. The inductor should have extremely low ESR and are available in small footprints. A low ESR (series resistance of the windings) to reduce the 4.7µF to 15µF output capacitor is sufficient for most I2R power losses, and must be able to handle the peak applications. Larger values up to 22µF may be used to inductor current without saturating. Molded chokes and obtain extremely low output voltage ripple and improve some chip inductors usually do not have enough core to transient response. An additional phase lead capacitor support the peak inductor currents of 850mA seen on the may be required with output capacitors larger than 10µF LTC3429/LTC3429B. To minimize radiated noise, use a to maintain acceptable phase margin. X5R and X7R toroid, pot core or shielded bobbin inductor. See Table 1 dielectric materials are preferred for their ability to main- for some suggested components and suppliers. tain capacitance over wide voltage and temperature ranges.
Table 1. Recommended Inductors
Low ESR input capacitors reduce input switching noise
MAX
and reduce the peak current drawn from the battery. It
L DCR HEIGHT
follows that ceramic capacitors are also a good choice for
PART (
µ
H) m
Ω
(mm) VENDOR
input decoupling and should be located as close as pos- CDRH5D18-4R1 4.1 57 2.0 Sumida CDRH5D18-100 10 124 2.0 www.sumida.com sible to the device. A 10µF input capacitor is sufficient for CDRH3D16-4R7 4.7 105 1.8 virtually any application. Larger values may be used with- CDRH3D16-6R8 170 1.8 out limitations. Table 2 shows a list of several ceramic CR43-4R7 4.7 109 3.5 CR43-100 10 182 3.5 capacitor manufacturers. Consult the manufacturers di- CMD4D06-4R7MC 4.7 216 0.8 rectly for detailed information on their entire selection of CMD4D06-3R3MC 3.3 174 0.8 ceramic capacitors. DS1608-472 4.7 60 2.9 Coilcraft
Table 2. Capacitor Vendor Information
DS1608-103 10 75 2.9 www.coilcraft.com DO1608C-472 4.7 90 2.9
SUPPLIER WEBSITE
D52LC-4R7M 4.7 84 2.0 Toko AVX www.avxcorp.com D52LC-100M 10 137 2.0 www.tokoam.com Murata www.murata.com LQH32CN4R7M24 4.7 195 2.2 Murata Taiyo Yuden www.t-yuden.com www.murata.com 3429fa 9