LM2679 - SIMPLE SWITCHER 5A Step-Down Voltage Regulator with Adjustable Current Limit
Datasheet Packaging Samples & Pricing Eval. Boards Reliability Design Tools Application Notes Knowledge Base

Features
•Efficiency up to 92%
•Simple and easy to design with (using off-the-shelf external components)
• Resistor programmable peak current limit over a range of 3A to 7A.
•120 mΩ DMOS output switch
•3.3V, 5V and 12V fixed output and adjustable (1.2V to 37V ) versions
•±2%maximum output tolerance over full line and load conditions
•Wide input voltage range: 8V to 40V
•260 KHz fixed frequency internal oscillator
•Softstart capability
•−40 to +125°C operating junction temperature range

General Description

The LM2679 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


ParametersValues
Output Current 5000 mA
Input Min Voltage 15, 8 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) 84, 92, 82 %
On/Off Pin No
Error Flag No
SoftStart Yes
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 Programmable current limit, 2% 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
AEC Q-100 Automotive Grade Undefined
Synchronous Rectification No


Typical Performance

*click for larger image


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LM2679
 
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


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Also Recommended
LM22679▲Wider Input Voltage Range (4.5V To 42V), Fixed 500kHz
Additional Resources
Online Seminars Design Tools

Application Notes


See Layout Guidelines

Block Diagram

click for larger image



Datasheet
RoHS Compliance Information Size in KbytesDate Click link below to Download
LM2679 SIMPLE SWITCHER 5A Step-Down Voltage Regulator with Adjustable Current Limit 672
Kbytes		 21-Feb-08 Download
LM2679 SIMPLE SWITCHER 5A Step-Down Voltage Regulator with Adjustable Current Limit (Japanese)
 699 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
LM2679-5.0EVALSIMPLE SWITCHER 5A Step-Down Voltage Regulator with Adjustable Current LimitFull productionN/A
 
Buy Now 		1+$30.001-
8 weeksN/A
LM2679SD-12LLP14RoHS Download Full productionN/A
 
Buy Now 		1K+$3.38reel
of
250		NS
UZXYTT
S0003FB
16 weeksN/A
LM2679SD-3.3LLP14NOPB1260RoHS Download Full productionN/A
Samples
Buy Now 		1K+$3.38reel
of
250		NS
UZXYTT
S0003HB
6 weeks500
LM2679SD-5.0LLP14NOPB1260RoHS Download Full productionN/A
 
Buy Now 		1K+$3.38reel
of
250		NS
UZXYTT
S0003JB
6 weeks500
LM2679SD-ADJLLP14NOPB
STD		1
1		260
260		RoHS Download Full productionN/A
Samples
Buy Now 		1K+$3.38reel
of
250		NS
UZXYTT
S0003KB
6 weeks500
LM2679SDX-12LLP14RoHS Download Full productionN/A
 
Buy Now 		1K+$3.38reel
of
2500		NS
UZXYTT
S0003FB
16 weeksN/A
LM2679SDX-3.3LLP14NOPB1260RoHS Download Full productionN/A
 
Buy Now 		1K+$3.38reel
of
2500		NS
UZXYTT
S0003HB
6 weeks3000
LM2679SDX-5.0LLP14RoHS Download Full productionN/A
 
Buy Now 		1K+$3.38reel
of
2500		NS
UZXYTT
S0003JB
16 weeksN/A
LM2679SDX-ADJLLP14NOPB1260RoHS Download Full productionN/A
 
Buy Now 		1K+$3.38reel
of
2500		NS
UZXYTT
S0003KB
8 weeks3000
LM2679T-12TO-2207NOPB1NARoHS Download Full productionN/A
Samples
Buy Now 		1K+$3.38rail
of
45		NSUZXYTTE#
LM2679
T-12
6 weeks100
LM2679T-3.3TO-2207NOPB
STD		1
1		NA
NA		RoHS Download Full productionN/A
Samples
Buy Now 		1K+$3.38rail
of
45		NSUZXYTTE#
LM2679
T-3.3
6 weeks500
LM2679T-5.0TO-2207NOPB
STD		1
1		NA
NA		RoHS Download Full productionN/A
Samples
Buy Now 		1K+$3.38rail
of
45		NSUZXYTTE#
LM2679
T-5.0
6 weeks500
LM2679T-ADJTO-2207NOPB
STD		1
1		NA
NA		RoHS Download Full productionN/A
Samples
Buy Now 		1K+$3.38rail
of
45		NSUZXYTTE#
LM2679
T-ADJ
8 weeks1000
LM2679S-12TO-2637NOPB
STD		3
3		245
235		RoHS Download Full productionN/A
 
Buy Now 		1K+$3.38rail
of
45		NSUZXYTTE#
LM2679
S-12
6 weeks500
LM2679S-3.3TO-2637NOPB
STD		3
3		245
235		RoHS Download Full productionN/A
Samples
Buy Now 		1K+$3.38rail
of
45		NSUZXYTTE#
LM2679
S-3.3
6 weeks500
LM2679S-5.0TO-2637NOPB
STD		3
3		245
235		RoHS Download Full productionN/A
Samples
Buy Now 		1K+$3.38rail
of
45		NSUZXYTTE#
LM2679
S-5.0
6 weeks500
LM2679S-ADJTO-2637NOPB
STD		3
3		245
235		RoHS Download Full productionN/A
Samples
Buy Now 		1K+$3.38rail
of
45		NSUZXYTTE#
LM2679
S-ADJ
8 weeks500
LM2679SX-12TO-2637NOPB3245RoHS Download Full productionN/A
 
Buy Now 		1K+$3.38reel
of
500		NSUZXYTTE#
LM2679
S-12
6 weeks2000
LM2679SX-3.3TO-2637NOPB3245RoHS Download Full productionN/A
 
Buy Now 		1K+$3.38reel
of
500		NSUZXYTTE#
LM2679
S-3.3
6 weeks1000
LM2679SX-5.0TO-2637NOPB
STD		3
3		245
235		RoHS Download Full productionN/A
 
Buy Now 		1K+$3.38reel
of
500		NSUZXYTTE#
LM2679
S-5.0
8 weeks1000
LM2679SX-ADJTO-2637NOPB
STD		3
3		245
235		RoHS Download Full productionN/A
 
Buy Now 		1K+$3.38reel
of
500		NSUZXYTTE#
LM2679
S-ADJ
6 weeks1000

Obsolete Versions

Obsolete PartAlternate Part or SupplierSourceLast Time Buy Date
LM2679LD-12
NONE
NONE
30 Jan 2004
LM2679LD-3.3
NONE
NONE
30 Jan 2004
LM2679LD-5.0
NONE
NONE
30 Jan 2004
LM2679LD-ADJ
NONE
NONE
30 Jan 2004
LM2679LDX-12
NONE
NONE
30 Jan 2004
LM2679LDX-3.3
NONE
NONE
30 Jan 2004
LM2679LDX-5.0
NONE
NONE
30 Jan 2004
LM2679LDX-ADJ
NONE
NONE
30 Jan 2004

General Description

The LM2679 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 LM2679 are available from several manufacturers to greatly simplify the design process.

Other features include the ability to reduce the input surge current at power-ON by adding a softstart timing capacitor to gradually turn on the regulator. The LM2679 series also has built in thermal shutdown and resistor programmable current limit of the power MOSFET switch to protect the device and load circuitry under fault conditions. 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)
LM2679S-12LMDMOS0177100024700002700869244
LM2679S-3.3LMDMOS0177100024700002700869244
LM2679S-5.0LMDMOS0177100024700002700869244
LM2679S-ADJLMDMOS0177100024700002700869244
LM2679SD-12LMDMOS0177100024700002700869244
LM2679SD-3.3LMDMOS0177100024700002700869244
LM2679SD-5.0LMDMOS0177100024700002700869244
LM2679SD-ADJLMDMOS0177100024700002700869244
LM2679SDX-12LMDMOS0177100024700002700869244
LM2679SDX-3.3LMDMOS0177100024700002700869244
LM2679SDX-5.0LMDMOS0177100024700002700869244
LM2679SDX-ADJLMDMOS0177100024700002700869244
LM2679SX-12LMDMOS0177100024700002700869244
LM2679SX-3.3LMDMOS0177100024700002700869244
LM2679SX-5.0LMDMOS0177100024700002700869244
LM2679SX-ADJLMDMOS0177100024700002700869244
LM2679T-12LMDMOS0177100024700002700869244
LM2679T-3.3LMDMOS0177100024700002700869244
LM2679T-5.0LMDMOS0177100024700002700869244
LM2679T-ADJLMDMOS0177100024700002700869244

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

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

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Application Notes

TitleSize in Kbytes Date Click link below to Download
AN-1135: Application Note 1135 LM267X 3A, 5A Evaluation Boards 1208
Kbytes		 10-May-04 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-May-04 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 162
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 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
 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 7-Nov-2009]