LM2678 - SIMPLE SWITCHER High Efficiency 5A Step-Down Voltage Regulator

Datasheet Packaging Samples & Pricing Reliability Design Tools Application Notes Knowledge Base

Features
Efficiency up to 92%
Simple and easy to design with (using off-the-shelf external components)
120 mΩ DMOS output switch
3.3V, 5V and 12V fixed output and adjustable (1.2V to 37V ) versions
50μA standby current when switched OFF
±2%maximum output tolerance over full line and load conditions
Wide input voltage range: 8V to 40V
260 KHz fixed frequency internal oscillator
−40 to +125°C operating junction temperature range

General Description


The LM2678 series of regulators are monolithic integrated circuits which provide all of the active functions for a step-down (buck) switching regulator capable of driving up to 5A loads with excellent line and load regulation characteristics. More...


Applications


Simple to design, high efficiency (>90%) step-down switching regulators
Efficient system pre-regulator for linear voltage regulators
Battery chargers
  Typical Application
click for larger image


Parametric Table     expand
Parametric Table    collapse
Output Current 5000 mA
Input Min Voltage 8, 15 Volt
Input Max Voltage 40 Volt
Output Min 3.3, 1.23, 12, 5 Volt
Output Max 3.3, 37, 12, 5 Volt
Frequency Min 260 kHz
Frequency Max 260 kHz
Output Current 5000 mA
Input Min Voltage 8, 15 Volt
Input Max Voltage 40 Volt
Output Min 3.3, 1.23, 12, 5 Volt
Output Max 3.3, 37, 12, 5 Volt
Frequency Min 260 kHz
Frequency Max 260 kHz
Efficiency (peak) 84, 92, 82 %
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, 2% output voltage accuracy, SIMPLE SWITCHER regulator
Step-Down Yes
Multiple Output Capability No
Output Power Undefined Watt
Output Voltage 3.3, Undefined, 12, 5 Volt
Output Range 5V, 12V, 1.23V to 37V, 3.3V
Switching Frequency 260 kHz
Regulator Family SIMPLE SWITCHER
AEC Q-100 Automotive Grade Undefined
Synchronous Rectification No
View Using Catalog


Typical Performance


*click for larger image


  WEBENCH Live Simulation!
LM2678 WEBENCH® Custom
Design/Analyze/Build It/Test It
 
8.00 <=
V in Lower
V
 
<=
V in Upper
V
 
<= 40.00
V out 1.21 <= V <= 40.00
I out   A <= 5.00
Ambient Temperature °C <= 100

What are WEBENCH® tools?


Also Recommended
LM22678500kHz, Adjustable Switching Frequency Up To 1MHz

Additional Resources


Design Tools (see below)

Application Notes (see below)


See Layout Guidelines

Block Diagram


click for larger image



Datasheet
RoHS Compliance Information Size in KbytesDate Click link below to Download
LM2678 SIMPLE SWITCHER High Efficiency 5A Step-Down Voltage Regulator 670 Kbytes 1-May-08 View Online
Download
LM2678 SIMPLE SWITCHER High Efficiency 5A Step-Down Voltage Regulator (Japanese)
1162 Kbytes   Download

If you have trouble printing or viewing PDF file(s), see Printing Problems.


Package Availability, Models, Samples & Pricing
Part NumberPackageFactory Lead TimeModelsSamples &
Electronic
Orders
Budgetary PricingStd
Pack
Size
Package
Marking
Format
TypePinsSpec.MSL
Rating
Peak
Reflow
RoHS
Report
CAD
Symbols
WeeksQtyQty$US each
LM2678SD-12LLP14NOPB1260RoHS Download Full productionN/A
 
Buy Now
1K+$3.13reel
of
250
NS
UZXYTT
S0003BB
6 weeksN/A
LM2678SD-3.3LLP14NOPB1260RoHS Download Full productionN/A
Samples
Buy Now
1K+$3.13reel
of
250
NS
UZXYTT
S0003CB
6 weeks500
LM2678SD-5.0LLP14NOPB1260RoHS Download Full productionN/A
Samples
Buy Now
1K+$3.13reel
of
250
NS
UZXYTT
S0003DB
6 weeks2000
LM2678SD-ADJLLP14STD
NOPB
1
1
260
260
RoHS Download Full productionN/A
Samples
Buy Now
1K+$3.13reel
of
250
NS
UZXYTT
S0003EB
6 weeks1000
LM2678SDX-12LLP14RoHS Download Full productionN/A
 
Buy Now
1K+$3.13reel
of
2500
NS
UZXYTT
S0003BB
16 weeksN/A
LM2678SDX-3.3LLP14RoHS Download Full productionN/A
 
Buy Now
1K+$3.13reel
of
2500
NS
UZXYTT
S0003CB
16 weeksN/A
LM2678SDX-5.0LLP14NOPB1260RoHS Download Full productionN/A
 
Buy Now
1K+$3.13reel
of
2500
NS
UZXYTT
S0003DB
6 weeksN/A
LM2678SDX-ADJLLP14STD
NOPB
1
1
260
260
RoHS Download Full productionN/A
 
Buy Now
1K+$3.13reel
of
2500
NS
UZXYTT
S0003EB
6 weeks15000
LM2678T-12TO-2207NOPB1NARoHS Download Full productionN/A
Samples
Buy Now
1K+$3.13rail
of
45
NSUZXYTTE#
LM2678
T-12
6 weeks500
LM2678T-3.3TO-2207NOPB1NARoHS Download Full productionN/A
Samples
Buy Now
1K+$3.13rail
of
45
NSUZXYTTE#
LM2678
T-3.3
6 weeks1000
LM2678T-5.0TO-2207STD
NOPB
1
1
NA
NA
RoHS Download Full productionN/A
Samples
Buy Now
1K+$3.13rail
of
45
NSUZXYTTE#
LM2678
T-5.0
6 weeks500
LM2678T-ADJTO-2207STD
NOPB
1
1
NA
NA
RoHS Download Full productionN/A
Samples
Buy Now
1K+$3.13rail
of
45
NSUZXYTTE#
LM2678
T-ADJ
6 weeks500
LM2678S-12TO-2637STD
NOPB
3
3
235
245
RoHS Download Full productionN/A
Samples
Buy Now
1K+$3.13rail
of
45
NSUZXYTTE#
LM2678
S-12
6 weeks500
LM2678S-3.3TO-2637STD
NOPB
3
3
235
245
RoHS Download Full productionN/A
Samples
Buy Now
1K+$3.13rail
of
45
NSUZXYTTE#
LM2678
S-3.3
6 weeks500
LM2678S-5.0TO-2637STD
NOPB
3
3
235
245
RoHS Download Full productionN/A
Samples
Buy Now
1K+$3.13rail
of
45
NSUZXYTTE#
LM2678
S-5.0
6 weeks500
LM2678S-ADJTO-2637STD
NOPB
3
3
235
245
RoHS Download Full productionN/A
Samples
Buy Now
1K+$3.13rail
of
45
NSUZXYTTE#
LM2678
S-ADJ
6 weeks2000
LM2678SX-12TO-2637NOPB3245RoHS Download Full productionN/A
 
Buy Now
1K+$3.13reel
of
500
NSUZXYTTE#
LM2678
S-12
6 weeks2500
LM2678SX-3.3TO-2637STD
NOPB
3
3
235
245
RoHS Download Full productionN/A
 
Buy Now
1K+$3.13reel
of
500
NSUZXYTTE#
LM2678
S-3.3
6 weeks1000
LM2678SX-5.0TO-2637STD
NOPB
3
3
235
245
RoHS Download Full productionN/A
 
Buy Now
1K+$3.13reel
of
500
NSUZXYTTE#
LM2678
S-5.0
6 weeks2000
LM2678SX-ADJTO-2637STD
NOPB
3
3
235
245
RoHS Download Full productionN/A
 
Buy Now
1K+$3.13reel
of
500
NSUZXYTTE#
LM2678
S-ADJ
6 weeks1000

Obsolete Parts

Obsolete PartAlternate Part or SupplierSourceLast Time Buy Date
LM2678LD-12
LM2678SD-12
NATIONAL SEMICONDUCTOR
01/30/2004
LM2678LD-3.3
LM2678SD-3.3
NATIONAL SEMICONDUCTOR
01/30/2004
LM2678LD-5.0
LM2678SD-5.0
NATIONAL SEMICONDUCTOR
01/30/2004
LM2678LD-ADJ
LM2678SD-ADJ
NATIONAL SEMICONDUCTOR
01/30/2004
LM2678LDX-12
LM2678SDX-12
NATIONAL SEMICONDUCTOR
01/30/2004
LM2678LDX-3.3
LM2678SDX-3.3
NATIONAL SEMICONDUCTOR
01/30/2004
LM2678LDX-5.0
LM2678SDX-5.0
NATIONAL SEMICONDUCTOR
01/30/2004
LM2678LDX-ADJ
LM2678SDX-ADJ
NATIONAL SEMICONDUCTOR
01/30/2004

General Description


The LM2678 series of regulators are monolithic integrated circuits which provide all of the active functions for a step-down (buck) switching regulator capable of driving up to 5A loads with excellent line and load regulation characteristics. High efficiency (>90%) is obtained through the use of a low ON-resistance DMOS power switch. The series consists of fixed output voltages of 3.3V, 5V and 12V and an adjustable output version.

The SIMPLE SWITCHER concept provides for a complete design using a minimum number of external components. A high fixed frequency oscillator (260KHz) allows the use of physically smaller sized components. A family of standard inductors for use with the LM2678 are available from several manufacturers to greatly simplify the design process.

The LM2678 series also has built in thermal shutdown, current limiting and an ON/OFF control input that can power down the regulator to a low 50μA quiescent current standby condition. The output voltage is guaranteed to a ±2% tolerance. The clock frequency is controlled to within a ±11% tolerance.

Reliability Metrics


Part Number Process EFR Reject EFR Sample Size PPM * LTA Rejects LTA Device Hours FITS MTTF (Hours)
LM2678S-12LMDMOS0151900017500003496567278
LM2678S-3.3LMDMOS0151900017500003496567278
LM2678S-5.0LMDMOS0151900017500003496567278
LM2678S-ADJLMDMOS0151900017500003496567278
LM2678SD-12LMDMOS0151900017500003496567278
LM2678SD-3.3LMDMOS0151900017500003496567278
LM2678SD-5.0LMDMOS0151900017500003496567278
LM2678SD-ADJLMDMOS0151900017500003496567278
LM2678SDX-12LMDMOS0151900017500003496567278
LM2678SDX-3.3LMDMOS0151900017500003496567278
LM2678SDX-5.0LMDMOS0151900017500003496567278
LM2678SDX-ADJLMDMOS0151900017500003496567278
LM2678SX-12LMDMOS0151900017500003496567278
LM2678SX-3.3LMDMOS0151900017500003496567278
LM2678SX-5.0LMDMOS0151900017500003496567278
LM2678SX-ADJLMDMOS0151900017500003496567278
LM2678T-12LMDMOS0151900017500003496567278
LM2678T-3.3LMDMOS0151900017500003496567278
LM2678T-5.0LMDMOS0151900017500003496567278
LM2678T-ADJLMDMOS0151900017500003496567278

Note: The Early Failure Rates were calculated as point estimates. 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


TitleSize in Kbytes Date Click link below to Download    
SimpleSwitcher® DC-DC Converters Design Software 12 Kbytes 11-Jan-2008 View    

If you have trouble printing or viewing PDF file(s), see Printing Problems.

Application Notes


TitleSize in Kbytes Date Click link below to Download
AN-1135: Application Note 1135 LM267X 3A, 5A Evaluation Boards 1208 Kbytes 1-Oct-02 Download

If you have trouble printing or viewing PDF file(s), see Printing Problems.

More Application Notes


TitleSize in Kbytes Date Click link below to Download
AN-1157: Application Note 1157 Positive to Negative Buck-Boost Converter Using LM267X SIMPLE SWITCHER® Regulators 189 Kbytes 1-Oct-02 Download
AN-1157 (Japanese): Application Note 1157 Positive to Negative Buck-Boost Converter Using LM267X SIMPLE SWITCHER® Regulators
193 Kbytes   Download
AN-1157 (Chinese): Application Note 1157 Positive to Negative Buck-Boost Converter Using LM267X SIMPLE SWITCHER® Regulators
307 Kbytes  
AN-1061: Application Note 1061 Power Conversion in Line-Powered Equipment 188 Kbytes 1-Oct-02 Download
AN-1061 (Japanese): Application Note 1061 Power Conversion in Line-Powered Equipment
215 Kbytes   Download
AN-1120: Application Note 1120 LM2675-5.0EVAL 1A Step-Down High-Efficiency SIMPLE SWITCHER Evaluation Board 44 Kbytes 23-Sep-02 Download
AN-1229: Application Note 1229 SIMPLE SWITCHER PCB Layout Guidelines 229 Kbytes 1-Oct-02 Download
AN-1229 (Japanese): Application Note 1229 SIMPLE SWITCHER PCB Layout Guidelines
304 Kbytes   Download
AN-1229 (Chinese): Application Note 1229 SIMPLE SWITCHER PCB Layout Guidelines
668 Kbytes  

If you have trouble printing or viewing PDF file(s), see Printing Problems.

[Information as of 21-Nov-2008]