MPS MP1584 - MP1584 Application Information: Component Selection (Continued)

MP1584 – 3A, 1.5MHz, 28V STEP-DOWN CONVERTER
MP1584 Rev. 1.0 www.MonolithicPower.com 11
8/8/2011 MPS Proprietary Information. Unauthorized Photocopy and Duplication Prohibited.
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Table 1—Inductor Selection Guide
Part Number Inductance (µH) Max DCR () Current Rating (A)
Dimensions
L x W x H (mm
3
)
Wurth Electronics
7447789003 3.3 0.024 3.42 7.3x7.3x3.2
744066100 10 0.035 3.6 10x10x3.8
744771115 15 0.025 3.75 12x12x6
744771122 22 0.031 3.37 12x12x6
TDK
RLF7030T-3R3 3.3 0.02 4.1 7.3x6.8x3.2
RLF7030T-4R7 4.7 0.031 3.4 7.3x6.8x3.2
SLF10145T-100 10 0.0364 3 10.1x10.1x4.5
SLF12565T-220M3R5 22 0.0316 3.5 12.5x12.5x6.5
Toko
FDV0630-3R3M 3.3 0.031 4.3 7.7x7x3
FDV0630-4R7M 4.7 0.049 3.3 7.7x7x3
919AS-100M 10 0.0265 4.3 10.3x10.3x4.5
919AS-160M 16 0.0492 3.3 10.3x10.3x4.5
919AS-220M 22 0.0776 3 10.3x10.3x4.5
Output Rectifier Diode
The output rectifier diode supplies the current to
the inductor when the high-side switch is off. To
reduce losses due to the diode forward voltage
and recovery times, use a Schottky diode.
Choose a diode whose maximum reverse
voltage rating is greater than the maximum
input voltage, and whose current rating is
greater than the maximum load current. Table 2
lists example Schottky diodes and
manufacturers.
Table 2—Diode Selection Guide
Diodes
Voltage/
Current
Rating
Manufacturer
B340A-13-F 40V, 3A Diodes Inc.
CMSH3-40MA 40V, 3A Central Semi
Input Capacitor
The input current to the step-down converter is
discontinuous, therefore a capacitor is required to
supply the AC current to the step-down converter
while maintaining the DC input voltage. Use low
ESR capacitors for the best performance. Ceramic
capacitors are preferred, but tantalum or low-ESR
electrolytic capacitors may also suffice.
For simplification, choose the input capacitor
with RMS current rating greater than half of the
maximum load current.