LM2577N-12 National Semiconductor, LM2577N-12 Datasheet - Page 15

• Manufacturer Part Number: LM2577N-12
• Description: SIMPLE SWITCHER Step-Up Voltage Regulator
• Manufacturer: National Semiconductor

Application Hints
Note: These charts assume that the inductor ripple current inductor is approximately 20% to 30% of the average inductor current (when the regulator is under
full load). Greater ripple current causes higher peak switch currents and greater output ripple voltage; lower ripple current is achieved with larger-value
inductors. The factor of 20 to 30% is chosen as a convenient balance between the two extremes.
C. Select an inductor from the table of Figure 10 which
cross-references the inductor codes to the part numbers
of three different manufacturers. Complete specifica-
tions for these inductors are available from the respec-
tive manufacturers. The inductors listed in this table
have the following characteristics:
AIE: ferrite, pot-core inductors; Benefits of this type are
low electro-magnetic interference (EMI), small physical
size, and very low power dissipation (core loss). Be
careful not to operate these inductors too far beyond
their maximum ratings for E • T and peak current, as this
will saturate the core.
Pulse: powdered iron, toroid core inductors; Benefits are
low EMI and ability to withstand E • T and peak current
above rated value better than ferrite cores.
Renco: ferrite, bobbin-core inductors; Benefits are low
cost and best ability to withstand E • T and peak current
above rated value. Be aware that these inductors gener-
ate more EMI than the other types, and this may inter-
fere with signals sensitive to noise.
FIGURE 9. LM1577-ADJ/LM2577-ADJ Inductor Selection Graph
(Continued)
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DS011468-12
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