LM2672M-5.0 National Semiconductor, LM2672M-5.0 Datasheet - Page 12
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LM2672M-5.0
Manufacturer Part Number
LM2672M-5.0
Description
DC/DC Converter IC
Manufacturer
National Semiconductor
Specifications of LM2672M-5.0
Input Voltage
40V
Output Current
1A
Output Voltage
5V
No. Of Pins
8
Mounting Type
Surface Mount
Voltage Regulator Type
Buck Switching
Supply Voltage Min
6.5V
Output Current Max
1A
Lead Free Status / RoHS Status
Contains lead / RoHS non-compliant
Available stocks
Company
Part Number
Manufacturer
Quantity
Price
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Part Number:
LM2672M-5.0
Manufacturer:
NS
Quantity:
4 000
Part Number:
LM2672M-5.0
Manufacturer:
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Quantity:
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5. Boost Capacitor (C
This capacitor develops the necessary voltage to turn the switch
gate on fully. All applications should use a 0.01 μF, 50V ceramic
capacitor.
6. Soft-Start Capacitor (C
This capacitor controls the rate at which the device starts up. The
formula for the soft-start capacitor C
where:
I
t
V
V
V
V
If this feature is not desired, leave this pin open. With certain
softstart capacitor values and operating conditions, the LM2672
can exhibit an overshoot on the output voltage during turn on.
Especially when starting up into no load or low load, the softstart
function may not be effective in preventing a larger voltage
overshoot on the output. With larger loads or lower input voltages
during startup this effect is minimized. In particular, avoid using
softstart capacitors between 0.033µF and 1µF.
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
= Soft-Start Current :4.5 μA typical.
= Soft-Start Time :Selected.
= Input Voltage :Selected.
= Output Voltage :Selected.
= Soft-Start Threshold Voltage :0.63V typical.
PROCEDURE (Fixed Output Voltage Version)
= Schottky Diode Voltage Drop :0.4V typical.
B
)
SS
- optional)
SS
is:
12
5. Boost Capacitor (C
For this application, and all applications, use a 0.01 μF, 50V
ceramic capacitor.
6. Soft-Start Capacitor (C
For this application, selecting a start-up time of 10 ms and using
the formula for C
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)
SS
results in a value of:
B
)
SS
- optional)