LM2679 - SIMPLE SWITCHER 5A Step-Down Voltage Regulator with Adjustable Current Limit

LM2679	SIMPLE SWITCHER 5A Step-Down Voltage Regulator with Adjustable Current Limit

Overview

Diagrams

Parametrics

Documents

Order

Boards

Packaging

Tools

Reliability

Obsolete Versions

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

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.

Applications
Simple to design, high efficiency (>90%) step-down switching regulators

Efficient system pre-regulator for linear voltage regulators

Battery chargers

See Layout Guidelines

WEBENCH® LM2679

Min Max Range

VIN – V    8.00 – 40.00V

VOUT V    1.21 – 40.00V

IOUT A    ≤ 5.00A

Ambient Temp °C    ≤ 100°C

Footprint BOM Cost Efficiency

What are WEBENCH® tools?

Also Recommended

LM22679▲ Wider Input Voltage Range (4.5V To 42V), Fixed 500kHz

Typical Application click for larger image

Block Diagram click for larger image

Typical Performance *click for larger image

Parameters / Values	LM2679	LM22679
Output Current	5000 mA	5000 mA
Input Min Voltage	15, 8 Volt	4.5 Volt
Input Max Voltage	40 Volt	42 Volt
Output Min	3.3, 1.23, 12, 5 Volt	1.285 Volt
Output Max	3.3, 12, 37, 5 Volt
Frequency Min	260 kHz
Frequency Max	260 kHz
Efficiency (peak)	84, 92, 82 %	92 %
On/Off Pin	No	No
PowerGood / Error Flag	No	No
SoftStart	Yes	Yes
Sync Pin	No	No
Flyback	No	No
RegType	Switching Regulator	Switching Regulator
Temperature Min	-40 deg C	-40 deg C
Temperature Max	125 deg C	125 deg C
Adjustable Output	Yes, No	Yes
Adj Switch Frequency	No	No
PWM Mode	Voltage with Vin Feedforward	Voltage Mode Control
Topology	Buck	Buck
Special Features	Programmable current limit, 2% output voltage accuracy, SIMPLE SWITCHER regulator	Adjustable Current Limit
Step-Down	Yes	Yes
Multiple Output Capability	No	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	500 kHz
Regulator Family	SIMPLE SWITCHER	SIMPLE SWITCHER
AEC Q-100 Automotive Grade	Undefined
Synchronous Rectification	No	No

Datasheets
Title Size Date Other
Language

LM2679 SIMPLE SWITCHER 5A Step-Down Voltage Regulator with Adjustable Current Limit 672
Kbytes 21-Feb-08 日本語

Application Notes
Title Size Date Other
Language

AN-1135: Application Note 1135 LM267X 3A, 5A Evaluation Boards 2433
Kbytes 4-Mar-11

Part Number(s)
(NSID)

Top View

Availability

Current Reported Stock

Budgetary Pricing

Pack
Size

LM2679S-12/NOPB

LM2679S-12

RoHS Status

TO-263

Full production
Lead Time: 6 weeks

Distributor	Region	Qty
ARROW	Worldwide	740
AVNET-EM	Worldwide	134
DIGI-KEY	Worldwide	393
FARNELL	Europe and Asia	2
MOUSER	Worldwide	135
NEWARK	Americas	96
TAYLOR	Americas	740

$3.38 each at 1K+ pcs

rail
of
45

LM2679S-3.3/NOPB

LM2679S-3.3

RoHS Status

TO-263

Full production
Lead Time: 6 weeks

Distributor	Region	Qty
AVNET-EM	Worldwide	478
DIGI-KEY	Worldwide	1047
MOUSER	Worldwide	95

$3.38 each at 1K+ pcs

rail
of
45

LM2679S-5.0/NOPB

LM2679S-5.0

RoHS Status

TO-263

Full production
Lead Time: 6 weeks

Distributor	Region	Qty
ARROW	Worldwide	135
AVNET-EM	Worldwide	1395
DIGI-KEY	Worldwide	1377
MOUSER	Worldwide	255
NEWARK	Americas	28
RS COMPONENTS	Worldwide	72
TAYLOR	Americas	224

$3.38 each at 1K+ pcs

rail
of
45

LM2679S-ADJ/NOPB

LM2679S-ADJ

RoHS Status

TO-263

Full production
Lead Time: 6 weeks

Distributor	Region	Qty
AECO TECH	Asia Pacific	40
ARROW	Worldwide	81
AVNET-EM	Worldwide	95
DIGI-KEY	Worldwide	15371
FARNELL	Europe and Asia	329
MOUSER	Worldwide	47
NEWARK	Americas	917
RS COMPONENTS	Worldwide	60
TAYLOR	Americas	2871

$3.38 each at 1K+ pcs

rail
of
45

LM2679SD-12

RoHS Status

LLP

Full production
Lead Time: 12 weeks

Distributor		Region	Qty
DIGI-KEY		Worldwide	0

$3.38 each at 1K+ pcs

reel
of
250

LM2679SD-3.3/NOPB

LM2679SD-3.3

RoHS Status

LLP

Full production
Lead Time: 6 weeks

Distributor		Region	Qty
DIGI-KEY		Worldwide	494
MOUSER		Worldwide	250

$3.38 each at 1K+ pcs

reel
of
250

LM2679SD-5.0/NOPB

LM2679SD-5.0

RoHS Status

LLP

Full production
Lead Time: 6 weeks

Distributor		Region	Qty
DIGI-KEY		Worldwide	1444
MOUSER		Worldwide	250

$3.38 each at 1K+ pcs

reel
of
250

LM2679SD-ADJ/NOPB

LM2679SD-ADJ

RoHS Status

LLP

Full production
Lead Time: 6 weeks

Distributor	Region	Qty
ARROW	Worldwide	250
DIGI-KEY	Worldwide	626
MOUSER	Worldwide	250
TAYLOR	Americas	250

$3.38 each at 1K+ pcs

reel
of
250

LM2679SDX-12

RoHS Status

LLP

Full production
Lead Time: 16 weeks

Distributor		Region	Qty
DIGI-KEY		Worldwide	0

$3.38 each at 1K+ pcs

reel
of
2500

LM2679SDX-3.3/NOPB

LM2679SDX-3.3

RoHS Status

LLP

Full production
Lead Time: 6 weeks

Distributor		Region	Qty
DIGI-KEY		Worldwide	0

$3.38 each at 1K+ pcs

reel
of
2500

LM2679SDX-5.0

RoHS Status

LLP

Full production
Lead Time: 16 weeks

Distributor		Region	Qty
DIGI-KEY		Worldwide	0

$3.38 each at 1K+ pcs

reel
of
2500

LM2679SDX-ADJ/NOPB

LM2679SDX-ADJ

RoHS Status

LLP

Full production
Lead Time: 6 weeks

Distributor		Region	Qty
DIGI-KEY		Worldwide	0

$3.38 each at 1K+ pcs

reel
of
2500

LM2679SX-12/NOPB

LM2679SX-12

RoHS Status

TO-263

Full production
Lead Time: 6 weeks

Distributor	Region	Qty
ARROW	Worldwide	500
DIGI-KEY	Worldwide	0
MOUSER	Worldwide	500
TAYLOR	Americas	500

$3.38 each at 1K+ pcs

reel
of
500

LM2679SX-3.3/NOPB

LM2679SX-3.3

RoHS Status

TO-263

Full production
Lead Time: 6 weeks

Distributor	Region	Qty
AVNET-EM	Worldwide	500
DIGI-KEY	Worldwide	1500
MOUSER	Worldwide	500

$3.38 each at 1K+ pcs

reel
of
500

LM2679SX-5.0/NOPB

LM2679SX-5.0

RoHS Status

TO-263

Full production
Lead Time: 6 weeks

Distributor	Region	Qty
ARROW	Worldwide	475
DIGI-KEY	Worldwide	0
MOUSER	Worldwide	500
TAYLOR	Americas	475
TECHMOSA	Asia Pacific	500

$3.38 each at 1K+ pcs

reel
of
500

LM2679SX-ADJ/NOPB

LM2679SX-ADJ

RoHS Status

TO-263

Full production
Lead Time: 6 weeks

Distributor	Region	Qty
ARROW	Worldwide	500
AVNET-EM	Worldwide	500
DIGI-KEY	Worldwide	0
MOUSER	Worldwide	480
TAYLOR	Americas	2900

$3.38 each at 1K+ pcs

reel
of
500

LM2679T-12/NOPB

LM2679T-12

RoHS Status

TO-220

Full production
Lead Time: 6 weeks

Distributor	Region	Qty
DIGI-KEY	Worldwide	145
MOUSER	Worldwide	135
RS COMPONENTS	Worldwide	10

$3.38 each at 1K+ pcs

rail
of
45

LM2679T-3.3/NOPB

LM2679T-3.3

RoHS Status

TO-220

Full production
Lead Time: 6 weeks

Distributor	Region	Qty
ARROW	Worldwide	535
AVNET-EM	Worldwide	562
DIGI-KEY	Worldwide	204
MOUSER	Worldwide	135
TAYLOR	Americas	545

$3.38 each at 1K+ pcs

rail
of
45

LM2679T-5.0/NOPB

LM2679T-5.0

RoHS Status

TO-220

Full production
Lead Time: 6 weeks

Distributor	Region	Qty
ARROW	Worldwide	900
AVNET-EM	Worldwide	752
DIGI-KEY	Worldwide	285
MOUSER	Worldwide	135
RS COMPONENTS	Worldwide	8
TAYLOR	Americas	900

$3.38 each at 1K+ pcs

rail
of
45

LM2679T-ADJ/NOPB

LM2679T-ADJ

RoHS Status

TO-220

Full production
Lead Time: 6 weeks

Distributor	Region	Qty
ARROW	Worldwide	315
AVNET-EM	Worldwide	2983
DIGI-KEY	Worldwide	168
FARNELL	Europe and Asia	164
MOUSER	Worldwide	128
NEWARK	Americas	111
RS COMPONENTS	Worldwide	45
TAYLOR	Americas	315

$3.38 each at 1K+ pcs

rail
of
45

Obsolete Versions

Obsolete Part Alternate Part or Supplier Source Last 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

All information pertaining to the RoHS Compliance Standard can be found at http://www.national.com/en/packaging/leadfree.html.

Moisture Sensitivity Level Data for LM2679.

A RoHS compliance or an IPC 1752 report can be acquired at http://www.national.com/en/packaging/greennopb.html.

National's certificate of product compliance for LM2679 is located at RoHS Status.

Part Number(s)
(NSID)

Description

Availability

Current Reported Stock

Budgetary Pricing

Pack
Size

LM2679-5.0EVAL

SIMPLE SWITCHER 5A Step-Down Voltage Regulator with Adjustable Current Limit

Full production

Distributor		Region	Qty
DIGI-KEY		Worldwide	0

$30.00 each

Description:

Simple Switcher 5A Step-Down Voltage Regulator with Adjustable Current Limit

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 m W 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 degrees C operating junction temperature range

Contents:

A fully assembled step-down DC/DC converter Evaluation Board using LM2679S-5.0
Power Manangement CD
Datasheets
Simple Switcher® selection guide
Evaluation board Application Note

National Semiconductor follows the provisions of the Product Stewardship Guide for Customers (CSP-9-111C1) and Banned Substances and Materials of Interest Specification (CSP-9-111S2) for regulatory environmental compliance. Details may be found at: www.national.com/en/packaging/greennopb.html. Lead free products are RoHS compliant.

Lead Free product status is available through the search tool located here

Part Number(s) (NSID)	Weight (milligrams)	Type	Pins	MSL Rating	Peak Reflow	RoHS Status	CAD Symbols	Models	Package Marking Format
LM2679S-12/NOPB LM2679S-12	1608.332 1609.822	TO-263	7	3 3	245 235	Detail	Download	N/A	NSUZXYTTE# LM2679 S-12
LM2679S-3.3/NOPB LM2679S-3.3	1608.332 1609.822	TO-263	7	3 3	245 235	Detail	Download	N/A	NSUZXYTTE# LM2679 S-3.3
LM2679S-5.0/NOPB LM2679S-5.0	1608.332 1609.822	TO-263	7	3 3	245 235	Detail	Download	N/A	NSUZXYTTE# LM2679 S-5.0
LM2679S-ADJ/NOPB LM2679S-ADJ	1608.332 1609.822	TO-263	7	3 3	245 235	Detail	Download	N/A	NSUZXYTTE# LM2679 S-ADJ
LM2679SD-12	94.76	LLP	14	1	260	Detail	Download	N/A	NS UZXYTT S0003FB
LM2679SD-3.3/NOPB LM2679SD-3.3	94.439 94.76	LLP	14	1 1	260 260	Detail	Download	N/A	NS UZXYTT S0003HB
LM2679SD-5.0/NOPB LM2679SD-5.0	94.439 94.76	LLP	14	1 1	260 260	Detail	Download	N/A	NS UZXYTT S0003JB
LM2679SD-ADJ/NOPB LM2679SD-ADJ	94.439 94.76	LLP	14	1 1	260 260	Detail	Download	N/A	NS UZXYTT S0003KB
LM2679SDX-12	94.76	LLP	14	1	260	Detail	Download	N/A	NS UZXYTT S0003FB
LM2679SDX-3.3/NOPB LM2679SDX-3.3	94.439 94.76	LLP	14	1 1	260 260	Detail	Download	N/A	NS UZXYTT S0003HB
LM2679SDX-5.0	94.76	LLP	14	1	260	Detail	Download	N/A	NS UZXYTT S0003JB
LM2679SDX-ADJ/NOPB LM2679SDX-ADJ	94.439 94.76	LLP	14	1 1	260 260	Detail	Download	N/A	NS UZXYTT S0003KB
LM2679SX-12/NOPB LM2679SX-12	1608.332 1609.822	TO-263	7	3 3	245 235	Detail	Download	N/A	NSUZXYTTE# LM2679 S-12
LM2679SX-3.3/NOPB LM2679SX-3.3	1608.332 1609.822	TO-263	7	3 3	245 235	Detail	Download	N/A	NSUZXYTTE# LM2679 S-3.3
LM2679SX-5.0/NOPB LM2679SX-5.0	1608.332 1609.822	TO-263	7	3 3	245 235	Detail	Download	N/A	NSUZXYTTE# LM2679 S-5.0
LM2679SX-ADJ/NOPB LM2679SX-ADJ	1608.332 1609.822	TO-263	7	3 3	245 235	Detail	Download	N/A	NSUZXYTTE# LM2679 S-ADJ
LM2679T-12/NOPB LM2679T-12	1846.782 1858.793	TO-220	7	1 1	NA NA	Detail	Download	N/A	NSUZXYTTE# LM2679 T-12
LM2679T-3.3/NOPB LM2679T-3.3	1846.782 1858.793	TO-220	7	1 1	NA NA	Detail	Download	N/A	NSUZXYTTE# LM2679 T-3.3
LM2679T-5.0/NOPB LM2679T-5.0	1846.782 1858.793	TO-220	7	1 1	NA NA	Detail	Download	N/A	NSUZXYTTE# LM2679 T-5.0
LM2679T-ADJ/NOPB LM2679T-ADJ	1846.782 1858.793	TO-220	7	1 1	NA NA	Detail	Download	N/A	NSUZXYTTE# LM2679 T-ADJ

All information pertaining to the RoHS Compliance Standard can be found at http://www.national.com/en/packaging/leadfree.html.

Moisture Sensitivity Level Data for LM2679.

A RoHS compliance or an IPC 1752 report can be acquired at http://www.national.com/en/packaging/greennopb.html.

National's certificate of product compliance for LM2679 is located at RoHS Status.

Design Tools
Title Size Date

SimpleSwitcher® DC-DC Converters Design Software

CAD Symbols and Models
Download LM2679 CAD Symbols

Models
N/A

Reliability Metrics

Part Number Process EFR Reject EFR Sample Size PPM LTA Rejects LTA Device Hours FITS MTTF (Hours)

LM2679S-12 LMDMOS 0 18295 0 0 2650000 2 751944735

LM2679S-3.3 LMDMOS 0 18295 0 0 2650000 2 751944735

LM2679S-5.0 LMDMOS 0 18295 0 0 2650000 2 751944735

LM2679S-ADJ LMDMOS 0 18295 0 0 2650000 2 751944735

LM2679SD-12 LMDMOS 0 18295 0 0 2650000 2 751944735

LM2679SD-3.3 LMDMOS 0 18295 0 0 2650000 2 751944735

LM2679SD-5.0 LMDMOS 0 18295 0 0 2650000 2 751944735

LM2679SD-ADJ LMDMOS 0 18295 0 0 2650000 2 751944735

LM2679SDX-12 LMDMOS 0 18295 0 0 2650000 2 751944735

LM2679SDX-3.3 LMDMOS 0 18295 0 0 2650000 2 751944735

LM2679SDX-5.0 LMDMOS 0 18295 0 0 2650000 2 751944735

LM2679SDX-ADJ LMDMOS 0 18295 0 0 2650000 2 751944735

LM2679SX-12 LMDMOS 0 18295 0 0 2650000 2 751944735

LM2679SX-3.3 LMDMOS 0 18295 0 0 2650000 2 751944735

LM2679SX-5.0 LMDMOS 0 18295 0 0 2650000 2 751944735

LM2679SX-ADJ LMDMOS 0 18295 0 0 2650000 2 751944735

LM2679T-12 LMDMOS 0 18295 0 0 2650000 2 751944735

LM2679T-3.3 LMDMOS 0 18295 0 0 2650000 2 751944735

LM2679T-5.0 LMDMOS 0 18295 0 0 2650000 2 751944735

LM2679T-ADJ LMDMOS 0 18295 0 0 2650000 2 751944735

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.

All information pertaining to the RoHS Compliance Standard can be found at http://www.national.com/en/packaging/leadfree.html.

Moisture Sensitivity Level Data for LM2679.

A RoHS compliance or an IPC 1752 report can be acquired at http://www.national.com/en/packaging/greennopb.html.

National's certificate of product compliance for LM2679 is located at RoHS Status.

[Information as of 9-Feb-2012]

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