LM2704-ADJMWC NSC [National Semiconductor], LM2704-ADJMWC Datasheet

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LM2704-ADJMWC

Manufacturer Part Number
LM2704-ADJMWC
Description
Micropower Step-up DC/DC Converter with 550mA Peak Current Limit
Manufacturer
NSC [National Semiconductor]
Datasheet
© 2003 National Semiconductor Corporation
LM2704
Micropower Step-up DC/DC Converter with 550mA Peak
Current Limit
General Description
The LM2704 is a micropower step-up DC/DC in a small
5-lead SOT-23 package. A current limited, fixed off-time
control scheme conserves operating current resulting in high
efficiency over a wide range of load conditions. The 21V
switch allows for output voltages as high as 20V. The low
400ns off-time permits the use of tiny, low profile inductors
and capacitors to minimize footprint and cost in space-
conscious portable applications. The LM2704 is ideal for
LCD panels requiring low current and high efficiency as well
as white LED applications for cellular phone back-lighting.
The LM2704 can drive up to 8 white LEDs from a single
Li-Ion battery.
DS200315
FIGURE 1. Typical 20V Application
Typical Application Circuit
Features
n 550mA, 0.7Ω, internal switch
n Uses small surface mount components
n Adjustable output voltage up to 20V
n 2.2V to 7V input range
n Input undervoltage lockout
n 0.01µA shutdown current
n Small 5-Lead SOT-23 package
Applications
n LCD Bias Supplies
n White LED Back-Lighting
n Handheld Devices
n Digital Cameras
n Portable Applications
20031501
www.national.com
April 2003

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LM2704-ADJMWC Summary of contents

Page 1

... The LM2704 is ideal for LCD panels requiring low current and high efficiency as well as white LED applications for cellular phone back-lighting. The LM2704 can drive white LEDs from a single Li-Ion battery. © 2003 National Semiconductor Corporation Features n 550mA, 0.7Ω ...

Page 2

... Connection Diagram Ordering Information Order Number Package Type LM2704MF-ADJ SOT23-5 LM2704MFX-ADJ SOT23-5 Pin Description/Functions Pin Name GND SHDN SW(Pin 1): Switch Pin. This is the drain of the internal NMOS power switch. Minimize the metal trace area con- nected to this pin to minimize EMI. ...

Page 3

Absolute Maximum Ratings If Military/Aerospace specified devices are required, please contact the National Semiconductor Sales Office/ Distributors for availability and specifications Voltage FB Voltage SHDN Voltage Maximum Junction Temp (Note 2) Lead Temperature (Soldering 10 ...

Page 4

Typical Performance Characteristics Enable Current vs V (Part Switching) Efficiency vs Load Current www.national.com IN 20031505 20031510 4 Disable Current (Part Not Switching) 20031506 Efficiency vs Load Current 20031511 ...

Page 5

Typical Performance Characteristics Efficiency vs Load Current Switch Current Limit vs V (Continued) 20031512 IN 20031514 5 SHDN Threshold 20031513 Switch DSON IN 20031515 www.national.com ...

Page 6

Typical Performance Characteristics FB Trip Point and FB Pin Current vs Temperature Step Response V = 20V 3.0V OUT IN 1) Load, 1mA to 17mA to 1mA 200mV/div, AC OUT 500mA/div, ...

Page 7

... Operation V = 20V 2.5V OUT 20V/div Inductor Current, 500mA/div 100mV/div, AC OUT T = 10µs/div FIGURE 2. LM2704 Block Diagram FIGURE 3. Typical Switching Waveform 7 20031504 20031518 www.national.com ...

Page 8

... Figure 3. When the FB pin drops slightly below 1.237V, the enable compara- tor enables the device and begins the cycle described pre- viously. The SHDN pin can be used to turn off the LM2704 and reduce the I to 0.01µA. In shutdown mode the output q voltage will be a diode drop lower than the input voltage ...

Page 9

Application Information (Continued) FIGURE 4. White LED Application FIGURE 5. Li-Ion 5V Application FIGURE 6. Li-Ion 12V Application 9 20031509 20031534 20031535 www.national.com ...

Page 10

Application Information www.national.com (Continued) FIGURE 12V Application 10 20031536 ...

Page 11

Physical Dimensions LIFE SUPPORT POLICY NATIONAL’S PRODUCTS ARE NOT AUTHORIZED FOR USE AS CRITICAL COMPONENTS IN LIFE SUPPORT DEVICES OR SYSTEMS WITHOUT THE EXPRESS WRITTEN APPROVAL OF THE PRESIDENT AND GENERAL COUNSEL OF NATIONAL SEMICONDUCTOR CORPORATION. As used herein: 1. ...

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