LM2671LD-12 NSC [National Semiconductor], LM2671LD-12 Datasheet - Page 13

• Manufacturer Part Number: LM2671LD-12
• Description: SIMPLE SWITCHER Power Converter High Efficiency 500mA Step-Down Voltage Regulator with Features
• Manufacturer: NSC [National Semiconductor]

7. Frequency Synchronization (optional)
The LM2671 (oscillator) can be synchronized to run with an
external oscillator, using the sync pin (pin 3). By doing so, the
LM2671 can be operated at higher frequencies than the
standard frequency of 260 kHz. This allows for a reduction in
the size of the inductor and output capacitor.
As shown in the drawing below, a signal applied to a RC filter at
the sync pin causes the device to synchronize to the frequency
of that signal. For a signal with a peak-to-peak amplitude of 3V
or greater, a 1 kΩ resistor and a 100 pF capacitor are suitable
values.
LM2671 Series Buck Regulator Design Procedure (Fixed Output)
INDUCTOR VALUE SELECTION GUIDES
(For Continuous Mode Operation)
PROCEDURE (Fixed Output Voltage Version)
FIGURE 4. LM2671-3.3
FIGURE 5. LM2671-5.0
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7. Frequency Synchronization (optional)
For all applications, use a 1 kΩ resistor and a 100 pF capacitor
for the RC filter.
EXAMPLE (Fixed Output Voltage Version)
FIGURE 7. LM2671-ADJ
FIGURE 6. LM2671-12
(Continued)
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