Datasheet LTC3402 (Analog Devices) - 9
| 制造商 | Analog Devices |
| 描述 | 2A, 3MHz Micropower Synchronous Boost Converter |
| 页数 / 页 | 16 / 9 — APPLICATIO S I FOR ATIO. COMPONENT SELECTION. Table 1. Inductor Vendor … |
| 文件格式/大小 | PDF / 235 Kb |
| 文件语言 | 英语 |
APPLICATIO S I FOR ATIO. COMPONENT SELECTION. Table 1. Inductor Vendor Information. SUPPLIER. PHONE. FAX. WEBSITE. Inductor Selection
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LTC3402
U U W U APPLICATIO S I FOR ATIO COMPONENT SELECTION Table 1. Inductor Vendor Information SUPPLIER PHONE FAX WEBSITE Inductor Selection
Coilcraft (847) 639-6400 (847) 639-1469 www.coilcraft.com The high frequency operation of the LTC3402 allows the Coiltronics (516) 241-7876 (516) 241-9339 www.coiltronics.com use of small surface mount inductors. The minimum Murata (814) 237-1431 (814) 238-0490 www.murata.com (800) 831-9172 inductance value is proportional to the operating fre- quency and is limited by the following constraints: Sumida USA: (847) 956-0666 (847) 956-0702 www.japanlink.com Japan: 81-3-3607-5111 81-3-3607-5144 sumida 3 V • V – V IN MIN ( ) OUT MAX ( ) IN MIN ( ) L > H μ and L > H f f • Ripple • VOUT MAX ( )
Output Capacitor Selection
where The output voltage ripple has several components. The f = Operating Frequency (Hz) bulk value of the capacitor is set to reduce the ripple due Ripple = Allowable Inductor Current Ripple (A) to charge into the capacitor each cycle. The max ripple due V to charge is given by: IN(MIN) = Minimum Input Voltage (V) VOUT(MAX) = Maximum Output Voltage (V) I V VR P IN = • V BULK The inductor current ripple is typically set to 20% to 40% C • V • f OUT OUT of the maximum inductor current. where IP = Peak Inductor Current Rt SHDN MODE VC The ESR can be a significant factor for ripple in most VIN FB SW VOUT power converters. The ripple due to capacitor ESR is GND POK simply given by: VRCESR = IP • RESR V where VOUT RESR = Capacitor Series Resistance 3402 F01 Low ESR capacitors should be used to minimize output
Figure 1. Recommended Component Placement. Traces
voltage ripple. For surface mount applications, AVX TPS
Carrying High Current Are Direct. Trace Area FB and VC Pins
series tantalum capacitors and Sanyo POSCAP or Taiyo-
Are Kept Low. Lead Length to Battery Should be Kept Short
Yuden ceramic X5R or X7R type capacitors are recom- mended. For through-hole applications Sanyo OS-CON For high efficiency, choose an inductor with a high fre- capacitors offer low ESR in a small package size. See Table quency core material, such as ferrite, to reduce core 2 for a list of component suppliers. In some layouts it may losses. The inductor should have low ESR (equivalent be required to place a 1μF low ESR capacitor as close to the series resistance) to reduce the I2R losses and must be VOUT and GND pins as possible. able to handle the peak inductor current without saturat- ing. Molded chokes or chip inductors usually do not have
Table 2. Capacitor Vendor Information
enough core to support the peak inductor currents in the
SUPPLIER PHONE FAX WEBSITE
1A to 2A region. To minimize radiated noise, use a toroid, AVX (803) 448-9411 (803) 448-1943 www.avxcorp.com pot core or shielded bobbin inductor. See Table 1 for Sanyo (619) 661-6322 (619) 661-1055 www.sanyovideo.com suggested components and Table 1 for a list of component Taiyo Yuden (408) 573-4150 (408) 573-4159 www.t-yuden.com suppliers. 3402fb 9
U U W U APPLICATIO S I FOR ATIO COMPONENT SELECTION Table 1. Inductor Vendor Information SUPPLIER PHONE FAX WEBSITE Inductor Selection
Coilcraft (847) 639-6400 (847) 639-1469 www.coilcraft.com The high frequency operation of the LTC3402 allows the Coiltronics (516) 241-7876 (516) 241-9339 www.coiltronics.com use of small surface mount inductors. The minimum Murata (814) 237-1431 (814) 238-0490 www.murata.com (800) 831-9172 inductance value is proportional to the operating fre- quency and is limited by the following constraints: Sumida USA: (847) 956-0666 (847) 956-0702 www.japanlink.com Japan: 81-3-3607-5111 81-3-3607-5144 sumida 3 V • V – V IN MIN ( ) OUT MAX ( ) IN MIN ( ) L > H μ and L > H f f • Ripple • VOUT MAX ( )
Output Capacitor Selection
where The output voltage ripple has several components. The f = Operating Frequency (Hz) bulk value of the capacitor is set to reduce the ripple due Ripple = Allowable Inductor Current Ripple (A) to charge into the capacitor each cycle. The max ripple due V to charge is given by: IN(MIN) = Minimum Input Voltage (V) VOUT(MAX) = Maximum Output Voltage (V) I V VR P IN = • V BULK The inductor current ripple is typically set to 20% to 40% C • V • f OUT OUT of the maximum inductor current. where IP = Peak Inductor Current Rt SHDN MODE VC The ESR can be a significant factor for ripple in most VIN FB SW VOUT power converters. The ripple due to capacitor ESR is GND POK simply given by: VRCESR = IP • RESR V where VOUT RESR = Capacitor Series Resistance 3402 F01 Low ESR capacitors should be used to minimize output
Figure 1. Recommended Component Placement. Traces
voltage ripple. For surface mount applications, AVX TPS
Carrying High Current Are Direct. Trace Area FB and VC Pins
series tantalum capacitors and Sanyo POSCAP or Taiyo-
Are Kept Low. Lead Length to Battery Should be Kept Short
Yuden ceramic X5R or X7R type capacitors are recom- mended. For through-hole applications Sanyo OS-CON For high efficiency, choose an inductor with a high fre- capacitors offer low ESR in a small package size. See Table quency core material, such as ferrite, to reduce core 2 for a list of component suppliers. In some layouts it may losses. The inductor should have low ESR (equivalent be required to place a 1μF low ESR capacitor as close to the series resistance) to reduce the I2R losses and must be VOUT and GND pins as possible. able to handle the peak inductor current without saturat- ing. Molded chokes or chip inductors usually do not have
Table 2. Capacitor Vendor Information
enough core to support the peak inductor currents in the
SUPPLIER PHONE FAX WEBSITE
1A to 2A region. To minimize radiated noise, use a toroid, AVX (803) 448-9411 (803) 448-1943 www.avxcorp.com pot core or shielded bobbin inductor. See Table 1 for Sanyo (619) 661-6322 (619) 661-1055 www.sanyovideo.com suggested components and Table 1 for a list of component Taiyo Yuden (408) 573-4150 (408) 573-4159 www.t-yuden.com suppliers. 3402fb 9