LM2672MX-ADJEP NSC [National Semiconductor], LM2672MX-ADJEP Datasheet

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LM2672MX-ADJEP

Manufacturer Part Number
LM2672MX-ADJEP
Description
Enhanced Plastic SIMPLE SWITCHER Power Converter High Efficiency 1A Step-Down Voltage Regulator with Features
Manufacturer
NSC [National Semiconductor]
Datasheet
1.LM2672MX-ADJEP.pdf (25 pages)
© 2004 National Semiconductor Corporation
LM2672EP
Enhanced Plastic SIMPLE SWITCHER
High Efficiency 1A Step-Down Voltage Regulator with
Features
General Description
The LM2672EP series of regulators are monolithic inte-
grated circuits built with a LMDMOS process. These regula-
tors provide all the active functions for a step-down (buck)
switching regulator, capable of driving a 1A load current with
excellent line and load regulation. These devices are avail-
able in fixed output voltages of 3.3V, 5.0V, 12V, and an
adjustable output version.
Requiring a minimum number of external components, these
regulators are simple to use and include patented internal
frequency compensation (Patent Nos. 5,382,918 and
5,514,947), fixed frequency oscillator, external shutdown,
soft-start, and frequency synchronization.
The LM2672EP series operates at a switching frequency of
260 kHz, thus allowing smaller sized filter components than
what would be needed with lower frequency switching regu-
lators. Because of its very high efficiency (
per traces on the printed circuit board are the only heat
sinking needed.
A family of standard inductors for use with the LM2672EP
are available from several different manufacturers. This fea-
ture greatly simplifies the design of switch-mode power sup-
plies using these advanced ICs. Also included in the
datasheet are selector guides for diodes and capacitors
designed to work in switch-mode power supplies.
Other features include a guaranteed
output voltage within specified input voltages and output
load conditions, and
ternal shutdown is included, featuring typically 50 µA
stand-by current. The output switch includes current limiting,
as well as thermal shutdown for full protection under fault
conditions.
To simplify the LM2672EP buck regulator design procedure,
there exists computer design software, LM267X Made
Simple version 6.0.
Ordering Information
SIMPLE SWITCHER
Windows
®
is a registered trademark of Microsoft Corporation.
PART NUMBER
LM2672MX-ADJEP
(Notes 1, 2)
®
is a registered trademark of National Semiconductor Corporation.
±
10% on the oscillator frequency. Ex-
±
DS200978
1.5% tolerance on
>
VID PART NUMBER
V62/04629-01
TBD
90%), the cop-
ENHANCED PLASTIC
• Extended Temperature Performance of −40˚C to +125˚C
• Baseline Control - Single Fab & Assembly Site
• Process Change Notification (PCN)
• Qualification & Reliability Data
• Solder (PbSn) Lead Finish is standard
• Enhanced Diminishing Manufacturing Sources (DMS)
Features
n Efficiency up to 96%
n Available in SO-8, 8-pin DIP and LLP packages
n Computer Design Software LM267X Made Simple
n Simple and easy to design with
n Requires only 5 external components
n Uses readily available standard inductors
n 3.3V, 5.0V, 12V, and adjustable output versions
n Adjustable version output voltage range: 1.21V to 37V
n
n Guaranteed 1A output load current
n 0.25Ω DMOS Output Switch
n Wide input voltage range: 8V to 40V
n 260 kHz fixed frequency internal oscillator
n TTL shutdown capability, low power standby mode
n Soft-start and frequency synchronization
n Thermal shutdown and current limit protection
Typical Applications
n Simple High Efficiency (
n Efficient Pre-Regulator for Linear Regulators
n Selected Military Applications
n Selected Avionics Applications
version 6.0
conditions
Regulator
±
Support
1.5% max output voltage tolerance over line and load
NS PACKAGE NUMBER (Note 3)
M08A
TBD
®
Power Converter
>
90%) Step-Down (Buck)
www.national.com
August 2004

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LM2672MX-ADJEP Summary of contents

Page 1

... To simplify the LM2672EP buck regulator design procedure, there exists computer design software, LM267X Made Simple version 6.0. Ordering Information PART NUMBER LM2672MX-ADJEP (Notes 1, 2) SIMPLE SWITCHER ® registered trademark of National Semiconductor Corporation. Windows ® ...

Page 2

... Note 1: For the following (Enhanced Plastic) versions, check for availability: LM2672LD-12EP, LM2672LD-3.3EP, LM2672LD-5.0EP, LM2672LD-ADJEP, LM2672LDX-12EP, LM2672LDX-3.3EP, LM2672LDX-5.0EP, LM2672LDX-ADJEP, LM2672M-12EP, LM2672M-3.3EP, LM2672M-5.0EP, LM2672M-ADJEP, LM2672MX-12EP, LM2672MX-3.3EP, LM2672MX-5.0EP, LM2672N-12EP, LM2672N-3.3EP, LM2672N-5.0EP, LM2672N-ADJEP. Parts listed with an "X" are provided in Tape & Reel and parts without an "X" are in Rails. ...

Page 3

Absolute Maximum Ratings If Military/Aerospace specified devices are required, please contact the National Semiconductor Sales Office/ Distributors for availability and specifications. Supply Voltage ON/OFF Pin Voltage Switch Voltage to Ground Boost Pin Voltage Feedback Pin Voltage ESD Susceptibility Human Body ...

Page 4

LM2672-ADJEP (Continued) Symbol Parameter η Efficiency V = 12V All Output Voltage Versions Specifications with standard type face are for T Range. Unless otherwise specified, V and I = 100 mA. LOAD Symbol Parameters DEVICE PARAMETERS I Quiescent ...

Page 5

Typical Performance Characteristics Normalized Output Voltage Efficiency Switch Current Limit 20097803 20097805 20097807 5 Line Regulation 20097804 Drain-to-Source Resistance 20097806 Operating Quiescent Current 20097808 www.national.com ...

Page 6

Typical Performance Characteristics Standby Quiescent Current ON/OFF Pin Current (Sourcing) Feedback Pin Bias Current www.national.com (Continued) 20097809 20097811 20097813 6 ON/OFF Threshold Voltage 20097810 Switching Frequency 20097812 Peak Switch Current 20097814 ...

Page 7

Typical Performance Characteristics Dropout Voltage — 3.3V Option Block Diagram * Patent Number 5,514,947 † Patent Number 5,382,918 (Continued) Dropout Voltage — 5.0V Option 20097815 FIGURE 1. Block Diagram 7 20097816 20097817 www.national.com ...

Page 8

Test Circuit and Layout Guidelines (Circuit of Figure 2) Continuous Mode Switching Waveforms V = 20V 5V OUT µ µF, C OUT A: V Pin Voltage, 10 V/div ...

Page 9

Test Circuit and Layout Guidelines µF, 50V Tantalum, Sprague “199D Series” µF, 25V Tantalum, Sprague “595D Series” OUT D1 - 3.3A, 50V Schottky Rectifier, IR 30WQ05F µH Sumida #RCR110D-680L C ...

Page 10

LM2672EP Series Buck Regulator Design Procedure (Fixed Output) PROCEDURE (Fixed Output Voltage Version) To simplify the buck regulator design procedure, National Semiconductor is making available computer design software to be used with the SIMPLE SWITCHER regulators. LM267X Made Simple version ...

Page 11

LM2672EP Series Buck Regulator Design Procedure (Fixed Output) (Continued) PROCEDURE (Fixed Output Voltage Version) The capacitor list contains through-hole electrolytic capacitors from four different capacitor manufacturers and surface mount tantalum capacitors from two different capacitor manufacturers recommended that ...

Page 12

LM2672EP Series Buck Regulator Design Procedure (Fixed Output) (Continued) PROCEDURE (Fixed Output Voltage Version) 4. Input Capacitor ( low ESR aluminum or tantalum bypass capacitor is needed between the input pin and ground to prevent large voltage ...

Page 13

LM2672EP Series Buck Regulator Design Procedure (Fixed Output) (Continued) PROCEDURE (Fixed Output Voltage Version) 7. Frequency Synchronization (optional) The LM2672EP (oscillator) can be synchronized to run with an external oscillator, using the sync pin (pin 3). By doing so, the ...

Page 14

Inductor Manufacturers’ Part Numbers Ind. Inductance Current Ref. Through (µH) (A) Desg. Hole L4 68 0.32 67143940 67144310 L5 47 0.37 67148310 67148420 L6 33 0.44 67148320 67148430 L7 22 0.52 67148330 67148440 L9 220 0.32 67143960 67144330 L10 150 ...

Page 15

Inductor Manufacturers’ Part Numbers Surface Mount Output Inductance Voltage Sprague (µH) (V) 594D Series (µF/V) 22 120/6.3 33 120/6.3 47 68/10 3.3 68 120/6.3 100 120/6.3 150 120/6.3 22 100/16 33 68/10 47 68/10 5.0 68 100/16 100 100/16 150 ...

Page 16

Inductor Manufacturers’ Part Numbers 20V 30V 40V 50V International Rectifier Corp. Motorola, Inc. General Instruments Corp. Diodes, Inc. FIGURE 14. RMS Current Ratings for Low ESR Electrolytic Capacitors (Typical) www.national.com (Continued) 1A Diodes 3A Diodes V Surface Through Surface R ...

Page 17

Inductor Manufacturers’ Part Numbers FIGURE 15. Recommended Application Voltage for AVX TPS and Sprague 594D Tantalum Chip Capacitors Derated for 85˚C. LM2672EP Series Buck Regulator Design Procedure (Adjustable Output) PROCEDURE (Adjustable Output Voltage Version) To simplify the buck regulator design ...

Page 18

LM2672EP Series Buck Regulator Design Procedure (Adjustable Output) (Continued) PROCEDURE (Adjustable Output Voltage Version) 2. Inductor Selection (L1) A. Calculate the inductor Volt • microsecond constant E • • µs), from the following formula: where V =internal switch ...

Page 19

LM2672EP Series Buck Regulator Design Procedure (Adjustable Output) (Continued) PROCEDURE (Adjustable Output Voltage Version) 4. Catch Diode Selection (D1 normal operation, the average current of the catch diode is the load current times the catch diode duty cycle, ...

Page 20

LM2672EP Series Buck Regulator Design Procedure (Adjustable Output) (Continued) Case Output Style (Note 10) Voltage (V) SM and TH 1.21–2.50 SM and TH 2.50–3.75 SM and TH 3.75–5.0 SM and TH 5.0–6.25 SM and TH 6.25–7.5 SM and TH 7.5–10.0 ...

Page 21

LM2672EP Series Buck Regulator Design Procedure (Adjustable Output) (Continued) Surface Mount Cap. Sprague AVX TPS Ref. Desg. 594D Series Series # (µF/V) (µF/V) C1 120/6.3 100/10 C2 120/6.3 100/10 C3 120/6.3 100/10 C4 68/10 100/10 C5 100/16 100/10 C6 100/16 ...

Page 22

Application Information TYPICAL SURFACE MOUNT PC BOARD LAYOUT, FIXD OUTPUT (4X SIZE µF, 50V, Solid Tantalum Sprague, “594D series” µF, 16V, Solid Tantalum Sprague, “594D series” OUT D1 - 1A, 40V Schottky Rectifier, ...

Page 23

Application Information LLP PACKAGE DEVICES The LM2672EP may be offered in the 16 lead LLP surface mount package to allow for increased power dissipation compared to the SO-8 and DIP. The Die Attach Pad (DAP) can and should be connected ...

Page 24

Physical Dimensions 8-Lead (0.150" Wide) Molded Small Outline Package, JEDEC www.national.com inches (millimeters) unless otherwise noted NS Package Number M08A 8-Lead (0.300" Wide) Molded Dual-In-Line Package NS Package Number N08E 24 ...

Page 25

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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