Datasheet LTC3417A (Analog Devices) - 10
| 制造商 | Analog Devices |
| 描述 | Dual Synchronous 1.5A/1A 4MHz Step-Down DC/DC Regulator |
| 页数 / 页 | 22 / 10 — applicaTions inForMaTion. Inductor Core Selection. Input Capacitor (CIN) … |
| 文件格式/大小 | PDF / 324 Kb |
| 文件语言 | 英语 |
applicaTions inForMaTion. Inductor Core Selection. Input Capacitor (CIN) Selection. Table 1 MANUFACTURER. PART NUMBER. VALUE (µH)
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LTC3417A
applicaTions inForMaTion Inductor Core Selection
RMS current must be used. Some capacitors have a Different core materials and shapes will change the size/ de-rating spec for maximum RMS current. If the capaci- current relationship of an inductor. Toroid or shielded tor being used has this requirement, it is necessary to pot cores in ferrite or permalloy materials are small and calculate the maximum RMS current. The RMS current don’t radiate much energy, but generally cost more than calculation is different if the part is used in “in phase” or powdered iron core inductors with similar electrical “out of phase”. characteristics. The choice of which style inductor to use For “in phase”, there are two different equations: often depends more on the price vs size requirements V of any radiated field/EMI requirements than on what the OUT1 > VOUT2: LTC3417A requires to operate. Table 1 shows some 2(D2 – D22)+I2(D1– D12) typical surface mount inductors that work well in IRMS = 2 •I1 •I2 • D2(1– D1)+I2 1 LTC3417A applications. VOUT2 > VOUT1:
Input Capacitor (CIN) Selection
2 2 IRMS = 2 • I1 • I2 • D1(1– D2)+I2(D2 – D22)+I1(D1– D12) In continuous mode, the input current of the converter can be approximated by the sum of two square waves with where: duty cycles of approximately VOUT1/VIN and VOUT2/VIN. To VOUT1 VOUT2 prevent large voltage transients, a low equivalent series D1= and D2 = VIN VIN resistance (ESR) input capacitor sized for the maximum
Table 1 MANUFACTURER PART NUMBER VALUE (µH) MAX DC CURRENT (A) DCR DIMENSIONS L
×
W
×
H (mm) L1 on OUT1
Toko A920CY-1R5M-D62CB 1.5 2.8 0.014 6 × 6 × 2.5 A918CY-1R5M-D62LCB 1.5 2.9 0.018 6 × 6 × 2 Coilcraft DO1608C-152ML 1.5 2.6 0.06 6.6 × 4.5 × 2.9 Sumida CDRH4D22/HP 1R5 1.5 3.9 0.031 5 × 5 × 2.4 Midcom DUP-1813-1R4R 1.4 5.5 0.033 4.3 × 4.8 × 3.5
L2 on OUT2
Toko A915AY-2R0M-D53LC 2.0 3.9 0.027 5 × 5 × 3 Coilcraft DO1608C-222ML 2.2 2.3 0.07 6.6 × 4.5 × 2.9 Sumida CDRH3D16/HP 2R2 2.2 1.75 0.047 4 × 4 × 1.8 CDRH2D18/HP 2R2 2.2 1.6 0.035 3.2 × 3.2 × 2 Midcom DUP-1813-2R2R 2.2 3.9 0.047 4.3 × 4.8 × 3.5 3417afc 10 Document Outline Features Description Applications Typical Application Absolute Maximum Ratings Pin Configuration Electrical Characteristics Typical Performance Characteristics Pin Functions Functional Diagram Operation Applications Information Package Description Revision History Related Parts
applicaTions inForMaTion Inductor Core Selection
RMS current must be used. Some capacitors have a Different core materials and shapes will change the size/ de-rating spec for maximum RMS current. If the capaci- current relationship of an inductor. Toroid or shielded tor being used has this requirement, it is necessary to pot cores in ferrite or permalloy materials are small and calculate the maximum RMS current. The RMS current don’t radiate much energy, but generally cost more than calculation is different if the part is used in “in phase” or powdered iron core inductors with similar electrical “out of phase”. characteristics. The choice of which style inductor to use For “in phase”, there are two different equations: often depends more on the price vs size requirements V of any radiated field/EMI requirements than on what the OUT1 > VOUT2: LTC3417A requires to operate. Table 1 shows some 2(D2 – D22)+I2(D1– D12) typical surface mount inductors that work well in IRMS = 2 •I1 •I2 • D2(1– D1)+I2 1 LTC3417A applications. VOUT2 > VOUT1:
Input Capacitor (CIN) Selection
2 2 IRMS = 2 • I1 • I2 • D1(1– D2)+I2(D2 – D22)+I1(D1– D12) In continuous mode, the input current of the converter can be approximated by the sum of two square waves with where: duty cycles of approximately VOUT1/VIN and VOUT2/VIN. To VOUT1 VOUT2 prevent large voltage transients, a low equivalent series D1= and D2 = VIN VIN resistance (ESR) input capacitor sized for the maximum
Table 1 MANUFACTURER PART NUMBER VALUE (µH) MAX DC CURRENT (A) DCR DIMENSIONS L
×
W
×
H (mm) L1 on OUT1
Toko A920CY-1R5M-D62CB 1.5 2.8 0.014 6 × 6 × 2.5 A918CY-1R5M-D62LCB 1.5 2.9 0.018 6 × 6 × 2 Coilcraft DO1608C-152ML 1.5 2.6 0.06 6.6 × 4.5 × 2.9 Sumida CDRH4D22/HP 1R5 1.5 3.9 0.031 5 × 5 × 2.4 Midcom DUP-1813-1R4R 1.4 5.5 0.033 4.3 × 4.8 × 3.5
L2 on OUT2
Toko A915AY-2R0M-D53LC 2.0 3.9 0.027 5 × 5 × 3 Coilcraft DO1608C-222ML 2.2 2.3 0.07 6.6 × 4.5 × 2.9 Sumida CDRH3D16/HP 2R2 2.2 1.75 0.047 4 × 4 × 1.8 CDRH2D18/HP 2R2 2.2 1.6 0.035 3.2 × 3.2 × 2 Midcom DUP-1813-2R2R 2.2 3.9 0.047 4.3 × 4.8 × 3.5 3417afc 10 Document Outline Features Description Applications Typical Application Absolute Maximum Ratings Pin Configuration Electrical Characteristics Typical Performance Characteristics Pin Functions Functional Diagram Operation Applications Information Package Description Revision History Related Parts