LM2623LDX NSC [National Semiconductor], LM2623LDX Datasheet

LM2623LDX

Manufacturer Part Number

LM2623LDX

Description

General Purpose, Gated Oscillator Based, DC/DC Boost Converter

Manufacturer

NSC [National Semiconductor]

Datasheet

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LM2623

General Purpose, Gated Oscillator Based, DC/DC Boost

Converter

General Description

The LM2623 is a high efficiency, general purpose, step-up

DC-DC switching regulator for battery-powered and low in-

put voltage systems. It accepts an input voltage between .8

and 14 volts and converts it into a regulated output voltage

between 1.24 and 14 volts. Efficiencies up to 90% are

achievable with the LM2623.

In order to adapt to a number of applications, the LM2623

allows the designer to vary the output voltage, the operating

frequency (300kHz to 2 MHz) and duty cycle (17% to 90%)

to optimize the part’s performance. The selected values can

be fixed or can vary with battery voltage or input to output

voltage ratio. The LM2623 uses a very simple, on/off regu-

lation mode to produce good efficiency and stable operation

over a wide operating range. It normally regulates by skip-

ping switching cycles when it reaches the regulation limit

(Pulse Frequency Modulation).

Note: Please read the "Non-Linear Effect" and "Choosing

The Correct C3 Capacitor" sub-sections of the Design Pro-

cedure section of this data sheet, so that any challenges with

designing with this part can be taken into account before a

board design/layout is finalized.

For Alternative Solutions, See Also: LM2700, LM2622,

LM2731, LM2733, and LM2621.

Typical Application Circuit

DS200388

Features

n Good Efficiency Over a Very Wide Load Range

n Very Low Output Voltage Ripple

n Small, Mini-SO-8 Package (Half the Footprint of

n 1.09 mm Package Height

n Up to 2 MHz Switching Frequency

n .8V to 14V Operating Voltage

n 1.1V Start-up Voltage

n 1.24V - 14V Adjustable Output Voltage

n Up to 2A Load Current at low Output Voltages

n 0.17Ω Internal MOSFET

n Up to 90% Regulator Efficiency

n 80 µA Typical Operating Current (into V

n 4mm x 4mm Thermally Enhanced LLP Package Option

Applications

n Cameras, Pagers and Cell Phones

n PDAs,Palmtop Computers, GPS devices

n White LED Drive, TFT or Scanned LCDs

n Flash Memory Programming

n Hand-Held Instruments

n 1, 2, 3 or 4 Cell Alkaline Systems

n 1, 2 or 3 Cell Lithium-ion Systems

Standard 8 pin SO Package)

2.5µA Guaranteed Supply Current In Shutdown

20038801

pin of supply)

www.national.com

July 2003

Related parts for LM2623LDX

LM2623LDX Summary of contents

Page 1

LM2623 General Purpose, Gated Oscillator Based, DC/DC Boost Converter General Description The LM2623 is a high efficiency, general purpose, step-up DC-DC switching regulator for battery-powered and low in- put voltage systems. It accepts an input voltage between .8 and 14 ...

Page 2

... Connection Diagram Ordering Information Order Number Package Type LM2623MMX Mini SO-8 LM2623AMMX Mini SO-8 LM2623AMM Mini SO-8 LM2623MM Mini SO-8 LM2623LDX LLP-14 LM2623ALDX LLP-14 LM2623LD LLP-14 LM2623ALD LLP-14 www.national.com LLP Package 20038802 Top View Mini SO-8 (MM) Package 20038818 Top View NSC Package Package Drawing Marking MUA08A ...

Page 3

Pin Description LLP-14 Pin MSOP-8 Pin 12 DAP Name Function NC No Connect Power Ground (LLP Pins 2 & ...

Page 4

Absolute Maximum Ratings If Military/Aerospace specified devices are required, please contact the National Semiconductor Sales Office/ Distributors for availability and specifications. SW Pin Voltage BOOT and FB Pins DD FREQ Pin T (Note 2) Jmax Storage Temperature ...

Page 5

Electrical Characteristics Note 8: Junction to ambient thermal resistance (θ standard JESD51-17. The test board layer FR-4 board measuring 102mm x 76mm x 1.6mm with array of thermal vias. The ground plane on ...

Page 6

Typical Performance Characteristics Efficiency 5.0V OUT Frequency vs V Typical R DS(ON) Temperature www.national.com IN 20038829 IN 20038828 vs 20038825 Temperature FB 20038831 Maximum Start Up Voltage vs Temperature 20038826 Typical Current Limit ...

Page 7

Detailed Description OPERATING PRINCIPLE The LM2623 is designed to provide step-up DC-DC voltage regulation in battery-powered and low-input voltage sys- tems. It combines a step-up switching regulator, N-channel power MOSFET, built-in current limit, thermal limit, and volt- age reference in ...

Page 8

Detailed Description PULSE FREQUENCY MODULATION (PFM) Pulse Frequency Modulation is typically accomplished by switching continuously until the voltage limit is reached and skipping cycles after that to just maintain it. This results in a somewhat hysteretic mode of operation. The ...

Page 9

Design Procedure NON-LINEAR EFFECT The LM2623 is very similar to the LM2621. The LM2623 is based on the LM2621, except for the fact that the LM2623 takes advantage of a non-linear effect that allows for the duty cycle to be ...

Page 10

Physical Dimensions For Order Numbers, refer to the table in the "Ordering Information" section of this document. www.national.com inches (millimeters) unless otherwise noted 8-Lead Mini SO-8 (MM) NS Package Number MUA08A 10 ...

Page 11

Physical Dimensions For Order Numbers, refer to the table in the "Ordering Information" section of this document. LIFE SUPPORT POLICY NATIONAL’S PRODUCTS ARE NOT AUTHORIZED FOR USE AS CRITICAL COMPONENTS IN LIFE SUPPORT DEVICES OR SYSTEMS WITHOUT THE EXPRESS WRITTEN ...

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