LM3578AN/NOPB National Semiconductor, LM3578AN/NOPB Datasheet - Page 18

• Manufacturer Part Number: LM3578AN/NOPB
• Description: IC REGULATOR SWITCHING 8-DIP
• Manufacturer: National Semiconductor
• Type: Step-Down (Buck), Step-Up (Boost), Inverting, Flybackr

Specifications of LM3578AN/NOPB

• Internal Switch(s): Yes
• Synchronous Rectifier: No
• Number Of Outputs: 1
• Current - Output: 750mA
• Frequency - Switching: 20kHz
• Voltage - Input: 2 ~ 40 V
• Operating Temperature: 0°C ~ 70°C
• Mounting Type: Through Hole
• Package / Case: 8-DIP (0.300", 7.62mm)
• Current, Input Bias: 4 μA
• Current, Output: 750 mA
• Current, Supply: 14 mA
• Frequency, Oscillator: 20 kHz
• Package Type: DIP-8
• Regulation, Line: 0.003 %/V
• Regulator Type: Boost, Buck, DC-DC, Switching
• Temperature, Operating, Range: 0 to +125 °C
• Voltage, Input: 2 to 40 V
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Voltage - Output: -
• Power - Output: -
• Lead Free Status / Rohs Status: RoHS Compliant part Electrostatic Device
• Other names: *LM3578AN; *LM3578AN/NOPB; LM3578AN; LM3578N

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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