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LM2674 -
SIMPLE SWITCHER® Power Converter High Efficiency 500mA Step-Down Voltage Regulator
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Features
| • | Efficiency up to 96% |
| • | Available in SO-8, 8-pin DIP and LLP packages |
| • | Computer Design Software LM267X Made Simple (version 6.0) |
| • | Simple and easy to design with |
| • | Requires only 5 external components |
| • | Uses readily available standard inductors |
| • | 3.3V, 5.0V, 12V, and adjustable output versions |
| • | Adjustable version output voltage range: 1.21V to 37V |
| • | ±1.5% max output voltage tolerance over line and load conditions |
| • | Guaranteed 500mA output load current |
| • | 0.25 DMOS Output Switch |
| • | Wide input voltage range: 8V to 40V |
| • | 260 kHz fixed frequency internal oscillator |
| • | TTL shutdown capability, low power standby mode |
| • | Thermal shutdown and current limit protection |
General Description
The LM2674 series of regulators are monolithic integrated circuits built with a LMDMOS process. More...
Applications
| • | Simple High Efficiency (>90%) Step-Down (Buck) Regulator |
| • | Efficient Pre-Regulator for Linear Regulators |
| • | Positive-to-Negative Converter |
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Typical Application
click for larger image
| Parameters | Values |
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| Output Current |
500 mA |
| Input Min Voltage |
6.5, 15 Volt |
| Input Max Voltage |
40 Volt |
| Output Min |
3.3, 1.23, 12, 5 Volt |
| Output Max |
3.3, 12, 37, 5 Volt |
| Frequency Min |
260 kHz |
| Frequency Max |
260 kHz |
| Efficiency (peak) |
90, 94, 86 % |
| On/Off Pin |
Yes |
| Error Flag |
No |
| SoftStart |
No |
| Sync Pin |
No |
| Flyback |
No |
| RegType |
Switching Regulator |
| Temperature Min |
-40 deg C |
| Temperature Max |
125 deg C |
| Adjustable Output |
Yes, No |
| Adj Switch Frequency |
No |
| PWM Mode |
Voltage with Vin Feedforward |
| Topology |
Buck |
| Special Features |
Internal Type 3 compensation, 1.5% output voltage accuracy, SIMPLE SWITCHER regulator |
| Step-Down |
Yes |
| Multiple Output Capability |
No |
| Output Power |
Undefined Watt |
| Output Voltage |
3.3, 12, Undefined, 5 Volt |
| Output Range |
12V, 1.23V to 37V, 3.3V, 5V |
| Switching Frequency |
260 kHz |
| Regulator Family |
SIMPLE SWITCHER |
| Synchronous Rectification |
No |
Typical Performance
*click for larger image
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WEBENCH Live Simulation!
Also Recommended
| LM22674▲ | Wider Input Voltage Range (4.5V To 42V), Fixed 500kHz |
Additional Resources
Design Tools
Application Notes
See Layout Guidelines
Block Diagram
click for larger image
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Datasheet
RoHS Compliance Information
| Size in Kbytes | Date |
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| LM2674 SIMPLE SWITCHER® Power Converter High Efficiency 500 mA Step-Down Voltage Regulator |
947
Kbytes |
1-Mar-05 |
Download |
LM2674 SIMPLE SWITCHER® Power Converter High Efficiency 500 mA Step-Down Voltage Regulator (Japanese)
 |
1055 Kbytes |
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Package Availability, Models, Samples & Pricing
| Obsolete Part | Alternate Part or
Supplier | Source | Last Time Buy Date |
LM2674LD-12
| NONE
| NATIONAL SEMICONDUCTOR
| 16 Nov 2008
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LM2674LD-5.0
| NONE
| NATIONAL SEMICONDUCTOR
| 16 Nov 2008
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LM2674LDX-12
| NONE
| NATIONAL SEMICONDUCTOR
| 16 Nov 2008
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LM2674LDX-3.3
| NONE
| NATIONAL SEMICONDUCTOR
| 16 Nov 2008
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LM2674LDX-ADJ
| NONE
| NATIONAL SEMICONDUCTOR
| 16 Nov 2008
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General Description
The LM2674 series of regulators are monolithic integrated circuits built with a LMDMOS process. These regulators provide all the active functions for a step-down (buck) switching regulator, capable of driving a 500 mA load current with excellent line and load regulation. These 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, these regulators are simple to use and include patented internal frequency compensation (Patent Nos. 5,382,918 and 5,514,947) and a fixed frequency oscillator.
The LM2674 series operates at a switching frequency of 260 kHz, thus allowing smaller sized filter components than what would be needed with lower frequency switching regulators. Because of its very high efficiency (>90%), the copper traces on the printed circuit board are the only heat sinking needed.
A family of standard inductors for use with the LM2674 are available from several different manufacturers. This feature greatly simplifies the design of switch-mode power supplies 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 ±1.5% tolerance on output voltage within specified input voltages and output load conditions, and ±10% on the oscillator frequency. External 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 LM2674 buck regulator design procedure, there exists computer design software, LM267X Made Simple (version 6.0).
Reliability Metrics
| Part Number |
Process |
EFR Reject |
EFR Sample Size |
PPM |
LTA Rejects |
LTA Device Hours |
FITS |
MTTF (Hours) |
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LM2674LD-3.3 | LMDMOS | 0 | 17710 | 0 | 0 | 2470000 | 2 | 700869244
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LM2674LD-ADJ | LMDMOS | 0 | 17710 | 0 | 0 | 2470000 | 2 | 700869244
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LM2674LDX-5.0 | LMDMOS | 0 | 17710 | 0 | 0 | 2470000 | 2 | 700869244
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LM2674M-12 | LMDMOS | 0 | 17710 | 0 | 0 | 2470000 | 2 | 700869244
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LM2674M-3.3 | LMDMOS | 0 | 17710 | 0 | 0 | 2470000 | 2 | 700869244
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LM2674M-5.0 | LMDMOS | 0 | 17710 | 0 | 0 | 2470000 | 2 | 700869244
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LM2674M-ADJ | LMDMOS | 0 | 17710 | 0 | 0 | 2470000 | 2 | 700869244
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LM2674MX-12 | LMDMOS | 0 | 17710 | 0 | 0 | 2470000 | 2 | 700869244
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LM2674MX-3.3 | LMDMOS | 0 | 17710 | 0 | 0 | 2470000 | 2 | 700869244
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LM2674MX-5.0 | LMDMOS | 0 | 17710 | 0 | 0 | 2470000 | 2 | 700869244
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LM2674MX-ADJ | LMDMOS | 0 | 17710 | 0 | 0 | 2470000 | 2 | 700869244
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LM2674N-12 | LMDMOS | 0 | 17710 | 0 | 0 | 2470000 | 2 | 700869244
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LM2674N-3.3 | LMDMOS | 0 | 17710 | 0 | 0 | 2470000 | 2 | 700869244
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LM2674N-5.0 | LMDMOS | 0 | 17710 | 0 | 0 | 2470000 | 2 | 700869244
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LM2674N-ADJ | LMDMOS | 0 | 17710 | 0 | 0 | 2470000 | 2 | 700869244
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Note: The Early Failure Rates (EFR) were calculated as point estimate PPM based on rejects and sample size for EFR.
The Long Term Failure Rates were calculated
at 60% confidence using the Arrhenius equation at 0.7eV activation energy and derating the assumed stress
temperature of 150°C to an application temperature of 55°C.
For more information on Reliability Metrics, please click here.
Design Tools
| Title | Size in Kbytes |
Date |
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| SimpleSwitcher® DC-DC Converters Design Software |
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View |
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Application Notes
| Title | Size in Kbytes |
Date |
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| AN-1061: Application Note 1061 Power Conversion in Line-Powered Equipment |
162
Kbytes |
1-Oct-02 |
Download |
AN-1061 (Japanese): Application Note 1061 Power Conversion in Line-Powered Equipment
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215 Kbytes |
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More Application Notes
| Title | Size in Kbytes |
Date |
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| AN-1135: Application Note 1135 LM267X 3A, 5A Evaluation Boards |
1208
Kbytes |
10-May-04 |
Download |
| AN-1157: Application Note 1157 Positive to Negative Buck‐Boost Converter Using LM267X SIMPLE SWITCHER® Regulators |
189
Kbytes |
1-May-04 |
Download |
AN-1157 (Japanese): Application Note 1157 Positive to Negative Buck‐Boost Converter Using LM267X SIMPLE SWITCHER® Regulators
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193 Kbytes |
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AN-1157 (Chinese): Application Note 1157 Positive to Negative Buck‐Boost Converter Using LM267X SIMPLE SWITCHER® Regulators
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307 Kbytes |
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| AN-1120: Application Note 1120 LM2675-5.0EVAL 1 Amp Step-Down High-Efficiency SIMPLE SWITCHER Evaluation Board |
44
Kbytes |
4-Oct-04 |
Download |
| AN-1229: Application Note 1229 SIMPLE SWITCHER PCB Layout Guidelines |
229
Kbytes |
1-May-04 |
Download |
AN-1229 (Japanese): Application Note 1229 SIMPLE SWITCHER PCB Layout Guidelines
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304 Kbytes |
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AN-1229 (Chinese): Application Note 1229 SIMPLE SWITCHER PCB Layout Guidelines
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668 Kbytes |
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[Information as of 7-Nov-2009]
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