LM2731YMFX/HALF National Semiconductor, LM2731YMFX/HALF Datasheet

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LM2731YMFX/HALF

Manufacturer Part Number
LM2731YMFX/HALF
Description
Manufacturer
National Semiconductor
Datasheet
1.LM2731YMFXHALF.pdf (16 pages)

Specifications of LM2731YMFX/HALF

Lead Free Status / RoHS Status
Supplier Unconfirmed
© 2007 National Semiconductor Corporation
LM2731
0.6/1.6 MHz Boost Converters With 22V Internal FET Switch
in SOT-23
General Description
The LM2731 switching regulators are current-mode boost
converters operating at fixed frequencies of 1.6 MHz (“X” op-
tion) and 600 kHz (“Y” option).
The use of SOT-23 package, made possible by the minimal
power loss of the internal 1.8A switch, and use of small in-
ductors and capacitors result in the industry's highest power
density. The 22V internal switch makes these solutions per-
fect for boosting to voltages up to 20V.
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.
Typical Application Circuit
1.6 MHz
Switch Frequency
X
0.6 MHz
Y
200591
Features
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Applications
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22V DMOS FET switch
1.6 MHz (“X”), 0.6 MHz (“Y”) switching frequency
Low R
Switch current up to 1.8A
Wide input voltage range (2.7V–14V)
Low shutdown current (<1 µA)
5-Lead SOT-23 package
Uses tiny capacitors and inductors
Cycle-by-cycle current limiting
Internally compensated
White LED Current Source
PDA’s and Palm-Top Computers
Digital Cameras
Portable Phones and Games
Local Boost Regulator
DS
(ON) DMOS FET
20059110
20059130
www.national.com
July 2007

LM2731YMFX/HALF Summary of contents

Page 1

... Internal compensation simplifies de- sign and reduces component count. Switch Frequency X 1.6 MHz 0.6 MHz Typical Application Circuit © 2007 National Semiconductor Corporation Features ■ 22V DMOS FET switch ■ 1.6 MHz (“X”), 0.6 MHz (“Y”) switching frequency ■ ...

Page 2

White LED Flash Application 2 20059153 20059156 20059155 ...

Page 3

Connection Diagram Ordering Information Order Package Package Supplied Number Type Drawing LM2731XMF LM2731XMFX SOT23-5 MF05A LM2731YMF LM2731YMFX Pin Descriptions Pin Name 1 SW Drain of the internal FET switch. 2 GND Analog and power ground Feedback point that ...

Page 4

Block Diagram Theory of Operation The LM2731 is a switching converter IC that operates at a fixed frequency (0.6 or 1.6 MHz) for fast transient response over a wide input voltage range and incorporates pulse-by- pulse current limiting protection. Because ...

Page 5

... Absolute Maximum Ratings If Military/Aerospace specified devices are required, please contact the National Semiconductor Sales Office/ Distributors for availability and specifications. Storage Temperature Range Operating Junction Temperature Range Lead Temp. (Soldering, 5 sec.) Power Dissipation (Note 2) Electrical Characteristics Limits in standard typeface are for T J ≤ ...

Page 6

Symbol Parameter D Maximum Duty Cycle MAX (Note 7) I Switch Leakage L Note 1: Absolute Maximum Ratings indicate limits beyond which damage to the component may occur. Electrical specifications do not apply when operating the device outside of the ...

Page 7

Oscillator Frequency vs Temperature - "X" Max. Duty Cycle vs Temperature - "X" Iq Vin (Idle) vs Temperature Oscillator Frequency vs Temperature - "Y" 20059105 Max. Duty Cycle vs Temperature - "Y" 20059107 Feedback Bias Current vs Temperature 20059125 7 ...

Page 8

Feedback Voltage vs Temperature Current Limit vs Temperature Efficiency vs Load Current - "X" 2.7V OUT www.national.com 20059127 20059129 = 5V 20059135 8 R (ON) vs Temperature DS 20059128 R (ON 20059152 ...

Page 9

Efficiency vs Load Current - "X" 4.2V OUT 20059137 Efficiency vs Load Current - "X" 3.3V 12V IN OUT 20059139 Efficiency vs Load Current - "X" 5V, V ...

Page 10

Efficiency vs Load Current - "Y" 3.3V OUT Efficiency vs Load Current - "Y" 2.7V OUT Efficiency vs Load Current - "Y" 5V OUT www.national.com = 5V 20059143 ...

Page 11

Application Hints SELECTING THE EXTERNAL CAPACITORS The best capacitors for use with the LM2731 are multi-layer ceramic capacitors. They have the lowest ESR (equivalent series resistance) and highest resonance frequency which makes them optimum for use with high frequency switching ...

Page 12

DUTY CYCLE The maximum duty cycle of the switching regulator deter- mines the maximum boost ratio of output-to-input voltage that the converter can attain in continuous mode of operation. The duty cycle for a given boost application is defined as: ...

Page 13

Switch Current Limit vs Duty Cycle - "X" Switch Current Limit vs Duty Cycle - "Y" CALCULATING LOAD CURRENT As shown in the figure which depicts inductor current, the load current is related to the average inductor current by the ...

Page 14

There will be some switching losses as well, so some derating needs to be applied when calculating IC power dissipation. INDUCTOR SUPPLIERS Recommended suppliers of inductors for this product include, but are not limited to Sumida, Coilcraft, Panasonic, TDK and ...

Page 15

Physical Dimensions inches (millimeters) unless otherwise noted Order Number LM2731XMF, LM2731XMFX, LM2731YMF or LM2731YMFX 5-Lead SOT-23 Package NS Package Number MF05A 15 www.national.com ...

Page 16

... National Semiconductor and the National Semiconductor logo are registered trademarks of National Semiconductor Corporation. All other brand or product names may be trademarks or registered trademarks of their respective holders. ...