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LM2733XMF PDF даташит

Спецификация LM2733XMF изготовлена ​​​​«National Semiconductor» и имеет функцию, называемую «0.6/1.6 MHz Boost Converters With 40V Internal FET».

Детали детали

Номер произв LM2733XMF
Описание 0.6/1.6 MHz Boost Converters With 40V Internal FET
Производители National Semiconductor
логотип National Semiconductor логотип 

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LM2733XMF Даташит, Описание, Даташиты
February 2003
LM2733
0.6/1.6 MHz Boost Converters With 40V Internal FET
Switch in SOT-23
General Description
The LM2733 switching regulators are current-mode boost
converters operating fixed frequency of 1.6 MHz (“X” option)
and 600 kHz (“Y” option).
The use of SOT-23 package, made possible by the minimal
power loss of the internal 1A switch, and use of small induc-
tors and capacitors result in the industry’s highest power
density. The 40V internal switch makes these solutions per-
fect for boosting to voltages of 16V or greater.
These parts have a logic-level shutdown pin that can be
used to reduce quiescent current and extend battery life.
Protection is provided through cycle-by-cycle current limiting
and thermal shutdown. Internal compensation simplifies de-
sign and reduces component count.
Switch Frequency
X
1.6 MHz
Y
0.6 MHz
Features
n 40V DMOS FET switch
n 1.6 MHz (“X”), 0.6 MHz (“Y”) switching frequency
n Low RDS(ON) DMOS FET
n Switch current up to 1A
n Wide input voltage range (2.7V–14V)
n Low shutdown current (<1 µA)
n 5-Lead SOT-23 package
n Uses tiny capacitors and inductors
n Cycle-by-cycle current limiting
n Internally compensated
Applications
n White LED Current Source
n PDA’s and Palm-Top Computers
n Digital Cameras
n Portable Phones and Games
n Local Boost Regulator
Typical Application Circuit
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© 2003 National Semiconductor Corporation DS200554
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LM2733XMF Даташит, Описание, Даташиты
Typical Application Circuit (Continued)
Connection Diagram
20055440
Top View
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20055402
5-Lead SOT-23 Package
See NS Package Number MF05A
Ordering Information
Order Number Package Type Package Drawing Supplied As Package ID
LM2733XMF
1K Tape and Reel S52A
LM2733XMFX
LM2733YMF
SOT23-5
MF05A
3K Tape and Reel
1K Tape and Reel
S52A
S52B
LM2733YMFX
3K Tape and Reel S52B
Pin Description
Pin Name
Function
1 SW Drain of the internal FET switch.
2
GND
Analog and power ground.
3 FB Feedback point that connects to external resistive divider.
4
SHDN
Shutdown control input. Connect to VIN if this feature is not used.
5 VIN Analog and power input.
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LM2733XMF Даташит, Описание, Даташиты
Block Diagram
Theory of Operation
The LM2733 is a switching converter IC that operates at a
fixed frequency (0.6 or 1.6 MHz) using current-mode control
for fast transient response over a wide input voltage range
and incorporate pulse-by-pulse current limiting protection.
Because this is current mode control, a 50 msense resis-
tor in series with the switch FET is used to provide a voltage
(which is proportional to the FET current) to both the input of
the pulse width modulation (PWM) comparator and the cur-
rent limit amplifier.
At the beginning of each cycle, the S-R latch turns on the
FET. As the current through the FET increases, a voltage
(proportional to this current) is summed with the ramp com-
ing from the ramp generator and then fed into the input of the
PWM comparator. When this voltage exceeds the voltage on
the other input (coming from the Gm amplifier), the latch
resets and turns the FET off. Since the signal coming from
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the Gm amplifier is derived from the feedback (which
samples the voltage at the output), the action of the PWM
comparator constantly sets the correct peak current through
the FET to keep the output volatge in regulation.
Q1 and Q2 along with R3 - R6 form a bandgap voltage
reference used by the IC to hold the output in regulation. The
currents flowing through Q1 and Q2 will be equal, and the
feedback loop will adjust the regulated output to maintain
this. Because of this, the regulated output is always main-
tained at a voltage level equal to the voltage at the FB node
"multiplied up" by the ratio of the output resistive divider.
The current limit comparator feeds directly into the flip-flop,
that drives the switch FET. If the FET current reaches the
limit threshold, the FET is turned off and the cycle terminated
until the next clock pulse. The current limit input terminates
the pulse regardless of the status of the output of the PWM
comparator.
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Номер в каталогеОписаниеПроизводители
LM2733XMF0.6/1.6 MHz Boost Converters With 40V Internal FETNational Semiconductor
National Semiconductor
LM2733XMFX0.6/1.6 MHz Boost Converters With 40V Internal FETNational Semiconductor
National Semiconductor

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