lm2577sx-adj National Semiconductor Corporation, lm2577sx-adj Datasheet - Page 17

• Manufacturer Part Number: lm2577sx-adj
• Description: Simple Switcher Step-up Voltage Regulator
• Manufacturer: National Semiconductor Corporation

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 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 gener-
ate more EMI than the other types, and this may interfere
with signals sensitive to noise.
FIGURE 9. LM1577-ADJ/LM2577-ADJ Inductor Selection Graph
(Continued)
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