LM1577, LM2577
SNOS658D –JUNE 1999–REVISED APRIL 2013
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Note: These charts assume that the inductor ripple current 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.
Figure 36. LM1577-ADJ/LM2577-ADJ Inductor Selection Graph
C.
Select an inductor from Table 2 which cross-references the inductor codes to the part numbers of three
different manufacturers. Complete specifications for these inductors are available from the respective
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 generate more EMI than the other types, and
this may interfere with signals sensitive to noise.
18
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