LM2672N-12 National Semiconductor, LM2672N-12 Datasheet - Page 13

• Manufacturer Part Number: LM2672N-12
• Description: Voltage Regulator IC
• Manufacturer: National Semiconductor

Specifications of LM2672N-12

• Output Current: 1A
• Output Voltage: 12V
• No. Of Pins: 8
• Peak Reflow Compatible (260 C): No
• Leaded Process Compatible: No
• Mounting Type: Through Hole
• Package / Case: 8 Lead
• Lead Free Status / RoHS Status: Contains lead / RoHS non-compliant

where:
I
t
V
V
V
V
If this feature is not desired, leave this pin open.
7. Frequency Synchronization (optional)
The LM2672 (oscillator) can be synchronized to run with an
external oscillator, using the sync pin (pin 3). By doing so, the
LM2672 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.
SS
SS
SSTH
OUT
SCHOTTKY
IN
LM2672 Series Buck Regulator Design Procedure (Fixed Output)
INDUCTOR VALUE SELECTION GUIDES (For
Continuous Mode Operation)
= Soft-Start Current :4.5 µA typical.
= Soft-Start Time :Selected.
= Input Voltage :Selected.
= Output Voltage :Selected.
PROCEDURE (Fixed Output Voltage Version)
= Soft-Start Threshold Voltage :0.63V typical.
= Schottky Diode Voltage Drop :0.4V typical.
FIGURE 4. LM2672-3.3
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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 5. LM2672-5.0
(Continued)
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01293430