LM2674
SIMPLE SWITCHER ®Power Converter High Efficiency 500mA Step-Down Voltage Regulator
General Description
The LM2674ries of regulators are monolithic integrated circuits built with a LMDMOS process.The regulators provide all the active functions for a step-down (buck)switching regulator,capable of driving a 500mA load current with excellent line and load regulation.The devices are available in fixed output voltages of 3.3V,5.0V,12V,and an adjustable output version.
Requiring a minimum number of external components,the regulators are simple to u and include patented internal frequency compensation (Patent Nos.5,382,918and 5,514,947)and a fixed frequency oscillator.
The LM2674ries operates at a switching frequency of 260kHz,thus allowing smaller sized filter components than what would be needed with lower frequency switching regu-lators.Becau of its very high efficiency (>90%),the cop-per traces on the printed circuit board are the only heat sinking needed.
A family of standard inductors for u with the LM2674are available from veral different manufacturers.This feature greatly simplifies the design of switch-mode power supplies using the advanced ICs.Also included in the datasheet are lector guides for diodes and capacitors designed
to work in switch-mode power supplies.
Other features include a guaranteed ±1.5%tolerance on output voltage within specified input voltages and output load conditions,and ±10%on the oscillator frequency.Ex-ternal shutdown is included,featuring typically 50µA stand-by current.The output switch includes current limiting,as well as thermal shutdown for full protection under fault conditions.
To simplify the LM2674buck regulator design procedure,there exists computer design software,LM267X Made Simple (version 6.0).
Features
n Efficiency up to 96%
n Available in SO-8,8-pin DIP and LLP packages n Computer Design Software LM267X Made Simple (version 6.0)
n Simple and easy to design with
中国励志人物n Requires only 5external components n Us 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 ±1.5%max output voltage tolerance over line and load conditions
n Guaranteed 500mA output load current n 0.25ΩDMOS Output Switch
n Wide input voltage range:8V to 40V
n 260kHz fixed frequency internal oscillator
n TTL shutdown capability,low power standby mode n Thermal shutdown and current limit protection
Typical Applications
n Simple High Efficiency (>90%)Step-Down (Buck)Regulator
n Efficient Pre-Regulator for Linear Regulators n Positive-to-Negative Converter
Typical Application
10004101
SIMPLE SWITCHER ®is a registered trademark of National Semiconductor Corporation.Windows ®is a registered trademark of Microsoft Corporation.
February 2005
LM2674SIMPLE SWITCHER Power Converter High Efficiency 500mA Step-Down Voltage Regulator
©2005National Semiconductor Corporation
Connection Diagrams
16-Lead LLP Surface Mount Package
双关是什么意思
Top View
8-Lead Package
Top View
10004138
LLP Package
See NSC Package Drawing Number LDA16A
10004102
喊组词SO-8/DIP Package
See NSC Package Drawing Number MO8A/N08E
TABLE 1.Package Marking and Ordering Information
Output Voltage Order Information
Package Marking
Supplied as:
16Lead LLP
12LM2674LD-12S0009B 1000Units on Tape and Reel 12LM2674LDX-12S0009B 4500Units on Tape and Reel 3.3LM2674LD-3.3S000AB 1000Units on Tape and Reel 3.3LM2674LDX-3.3S000AB 4500Units on Tape and Reel 5.0LM2674LD-5.0S000BB 1000Units on Tape and Reel 5.0LM2674LD
X-5.0S000BB 4500Units on Tape and Reel ADJ LM2674LD-ADJ S000CB 1000Units on Tape and Reel ADJ
LM2674LDX-ADJ
S000CB
4500Units on Tape and Reel
SO-8
12LM2674M-122674M-12Shipped in Anti-Static Rails 12LM2674MX-122674M-122500Units on Tape and Reel 3.3LM2674M-3.32674M-3.3Shipped in Anti-Static Rails 3.3LM2674MX-3.32674M-3.32500Units on Tape and Reel 5.0LM2674M-5.02674M-5.0Shipped in Anti-Static Rails 5.0LM2674MX-5.02674M-5.02500Units on Tape and Reel ADJ LM2674M-ADJ 2674M-ADJ Shipped in Anti-Static Rails ADJ
LM2674MX-ADJ
2674M-ADJ
2500Units on Tape and Reel
DIP
12LM2674N-12LM2674N-12Shipped in Anti-Static Rails 3.3LM2674N-3.3LM2674N-3.3Shipped in Anti-Static Rails 5.0LM2674N-5.0LM2674N-5.0Shipped in Anti-Static Rails ADJ
LM2674N-ADJ
LM2674N-ADJ
Shipped in Anti-Static Rails
L M 2674
2
Absolute Maximum Ratings(Note1)
If Military/Aerospace specified devices are required,plea contact the National Semiconductor Sales Office/ Distributors for availability and specifications.
Supply Voltage45V ON/OFF Pin Voltage−0.1V≤V SH≤6V Switch Voltage to Ground−1V Boost Pin Voltage V SW+8V Feedback Pin Voltage−0.3V≤V FB≤14V ESD Susceptibility
Human Body Model(Note2)2kV Power Dissipation Internally Limited Storage Temperature Range−65˚C to+150˚C Lead Temperature
M Package
Vapor Pha(60s)+215˚C Infrared(15s)+220˚C N Package(Soldering,10s)+260˚C LLP Package(See AN-1187)
Maximum Junction Temperature+150˚C
Operating Ratings
损的成语
Supply Voltage 6.5V to40V Junction Temperature Range−40˚C≤T J≤+125˚C Electrical Characteristics
LM2674-3.3Specifications with standard type face are for T
J
=25˚C,and tho with bold type face apply over full Operating Temperature Range.
Symbol Parameter Conditions Typical Min Max Units
(Note4)(Note5)(Note5) SYSTEM PARAMETERS Test Circuit Figure2(Note3)
V OUT Output Voltage V IN=8V to40V,I LOAD=20mA to500mA 3.3 3.251/3.201 3.350/3.399V V OUT Output Voltage V IN=6.5V to40V,I LOAD=20mA to250mA 3.3 3.251/3.201 3.350/3.399V ηEfficiency V IN=12V,I LOAD=500mA86% LM2674-5.0
Symbol Parameter Conditions Typical Min Max Units
(Note4)(Note5)(Note5) SYSTEM PARAMETERS Test Circuit Figure2(Note3)
V OUT Output Voltage V IN=8V to40V,I LOAD=20mA to500mA 5.0 4.925/4.850 5.075/5.150V V OUT Output Voltage V IN=6.5V to40V,I LOAD=20mA to250mA 5.0 4.925/4.850 5.075/5.150V ηEfficiency V IN=12V,I LOAD=500mA90% LM2674-12
Symbol Parameter Conditions Typical Min Max Units
锐利拼音(Note4)(Note5)(Note5) SYSTEM PARAMETERS Test Circuit Figure2(Note3)
V OUT Output Voltage V IN=15V to40V,I LOAD=20mA to500mA1211.82/11.6412.18/12.36V ηEfficiency V IN=24V,I LOAD=500mA94% LM2674-ADJ
Symbol Parameter Conditions Typ Min Max Units
(Note4)(Note5)(Note5) SYSTEM PARAMETERS Test Circuit Figure3(Note3)
V FB Feedback
Voltage V IN=8V to40V,I LOAD=20mA to500mA
V OUT Programmed for5V
(e Circuit of Figure3)
1.210 1.192/1.174 1.228/1.246V
买礼物的英文V FB Feedback
Voltage V IN=6.5V to40V,I LOAD=20mA to250mA
V OUT Programmed for5V
(e Circuit of Figure3)
1.210 1.192/1.174 1.228/1.246V
LM2674
3
LM2674-ADJ
(Continued)
Symbol Parameter Conditions
Typ Min Max Units
(Note 4)(Note 5)
(Note 5)
η
Efficiency
V IN =12V,I LOAD =500mA
90
%All Output Voltage Versions
Specifications with standard type face are for T J =25˚C,and tho with bold type face apply over full Operating Tempera-ture Range .Unless otherwi specified,V IN =12V for the 3.3V,5V,and Adjustable versions and V IN =24V for the 12V ver-sion,and I LOAD =100mA.Symbol Parameters
Conditions
Typ Min
Max Units DEVICE PARAMETERS
I Q
Quiescent Current
V FEEDBACK =8V
2.5
3.6
mA
For 3.3V,5.0V,and ADJ Versions V FEEDBACK =15V 2.5
mA
For 12V Versions
I STBY Standby Quiescent Current ON/OFF Pin =0V
50100/150µA I CL Current Limit
0.80.62/0.575
1.2/1.25A I L
Output Leakage Current
V IN =40V,ON/OFF Pin =0V V SWITCH =0V
125µA V SWITCH =−1V,ON/OFF Pin =0V
615mA R DS(ON)Switch On-Resistance I SWITCH =500mA 0.250.40/0.60Ωf O Oscillator Frequency Measured at Switch Pin 260225275
kHz D Maximum Duty Cycle 95%Minimum Duty Cycle 0%I BIAS Feedback Bias Current
V FEEDBACK =1.3V ADJ Version Only 85nA V S/D ON/OFF Pin
Voltage Thesholds 1.40.8 2.0V I S/D ON/OFF Pin Current ON/OFF Pin =0V
207
37
µA θJA
Thermal Resistance
N Package,Junction to Ambient (Note 6)95˚C/W
M Package,Junction to Ambient (Note 6)105
Note 1:Absolute Maximum Ratings indicate limits beyond which damage to the device may occur.Operating Ratings indicate conditions for which the device is intended to be functional,but device parameter specifications may not be guaranteed under the conditions.For guaranteed specifications and test conditions,e the Electrical Characteristics.
Note 2:The human body model is a 100pF capacitor discharged through a 1.5k Ωresistor into each pin.
Note 3:External components such as the catch diode,inductor,input and output capacitors,and voltage programming resistors can affect switching regulator performance.When the LM2674is ud as shown in Figures 2,3test circuits,system performance will be as specified by the system parameters ction of the Electrical Characteristics.
金鱼的眼泪
Note 4:Typical numbers are at 25˚C and reprent the most likely norm.
Note 5:All limits guaranteed at room temperature (standard type face)and at temperature extremes (bold type face).All room temperature limits are 100%production tested.All limits at temperature extremes are guaranteed via correlation using standard Statistical Quality Control (SQC)methods.All limits are ud to calculate Average Outgoing Quality Level (AOQL).
Note 6:Junction to ambient thermal resistance with approximately 1square inch of printed circuit board copper surrounding the leads.Additional copper area will lower thermal resistance further.See Application Information ction in the application note accompanying this datasheet and the thermal model in LM267X Made Simple (version 6.0)software.The value θJ−A for the LLP (LD)package is specifically dependent on PCB trace area,trace material,and the number of layers and thermal vias.For improved thermal resistance and power dissipation for the LLP package,refer to Application Note AN-1187.
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Typical Performance
Characteristics
Normalized
Output Voltage Line Regulation
1000410310004104
Efficiency
Drain-to-Source
企业职工Resistance
1000410510004106
Switch Current Limit
Operating
Quiescent Current
1000410710004108
LM2674
5
Typical Performance Characteristics
(Continued)
Standby
Quiescent Current
ON/OFF Threshold
Voltage
10004109
10004110
ON/OFF Pin Current (Sourcing)
Switching Frequency
1000411110004112
Feedback Pin Bias Current
Peak Switch Current
1000411310004114
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