LM2578AM National Semiconductor, LM2578AM Datasheet - Page 18

• Manufacturer Part Number: LM2578AM
• Description: IC,SMPS CONTROLLER,VOLTAGE-MODE,BIPOLAR,SOP,8PIN,PLASTIC
• Manufacturer: National Semiconductor

Specifications of LM2578AM

• Rohs Compliant: NO

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Typical Applications
A minimum value for an ideal output capacitor C3, could be
calculated as C = I
the transistor on time (typically 0.4/f
to-peak output voltage ripple. A larger output capacitor than
this theoretical value should be used since electrolytics have
poor high frequency performance. Experience has shown
that a value from 5 to 10 times the calculated value should
be used.
For good efficiency, the diodes must have a low forward
voltage drop and be fast switching. 1N5819 Schottky diodes
work well.
o
x t/∆V where I
o
osc
(Continued)
is the load current, t is
), and ∆V is the peak-
18
Transformer selection should be picked for an output tran-
sistor “on” time of 0.4/f
enough to prevent the output transistor switch from ramping
higher than the transistor’s rating of 750 mA. Pulse Engi-
neering (San Diego, Calif.) and Renco Electronics, Inc.
(Deer Park, N.Y.) can provide further assistance in selecting
the proper transformer for a specific application need. The
transformer used in Figure 23 was a Pulse Engineering
PE-64287.
osc
, and a primary inductance high