LM2672
LM2672 Series Buck Regulator Design Procedure (Fixed Output)
PROCEDURE (Fixed Output Voltage Version)
(Continued)
EXAMPLE (Fixed Output Voltage Version)
where:
I
SS
= Soft-Start Current :4.5 µA typical.
t
SS
= Soft-Start Time :Selected.
V
SSTH
= Soft-Start Threshold Voltage :0.63V typical.
V
OUT
= Output Voltage :Selected.
V
SCHOTTKY
= Schottky Diode Voltage Drop :0.4V typical.
V
IN
= Input Voltage :Selected.
If this feature is not desired, leave this pin open.
7. Frequency Synchronization (optional)
7. Frequency Synchronization (optional)
The LM2672 (oscillator) can be synchronized to run with an
For all applications, use a 1 kΩ resistor and a 100 pF capacitor
external oscillator, using the sync pin (pin 3). By doing so, the
for the RC filter.
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.
INDUCTOR VALUE SELECTION GUIDES
(For
Continuous Mode Operation)
01293430
01293429
FIGURE 5. LM2672-5.0
FIGURE 4. LM2672-3.3
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