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

	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

500kHz, 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 Kbytes	Date
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

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

Package Availability, Models, Samples & Pricing

Part Number

Package

Factory Lead Time

Models

Samples &
Electronic
Orders

Budgetary Pricing

Std
Pack
Size

Package
Marking
Format

Type

Pins

Spec.

MSL
Rating

Peak
Reflow

RoHS
Report

CAD
Symbols

Qty

Qty

$US each

LM2678SD-12

14

NOPB

1

260

Full production

N/A

1K+

$3.13

reel
of
250

NS
UZXYTT
S0003BB

6 weeks

N/A

LM2678SD-3.3

14

NOPB

1

260

Full production

N/A

Samples

1K+

$3.13

reel
of
250

NS
UZXYTT
S0003CB

6 weeks

500

LM2678SD-5.0

14

NOPB

1

260

Full production

N/A

Samples

1K+

$3.13

reel
of
250

NS
UZXYTT
S0003DB

6 weeks

2000

LM2678SD-ADJ

14

STD

NOPB

1

1

260

260

Full production

N/A

Samples

1K+

$3.13

reel
of
250

NS
UZXYTT
S0003EB

6 weeks

1000

LM2678SDX-12

14

Full production

N/A

1K+

$3.13

reel
of
2500

NS
UZXYTT
S0003BB

16 weeks

N/A

LM2678SDX-3.3

14

Full production

N/A

1K+

$3.13

reel
of
2500

NS
UZXYTT
S0003CB

16 weeks

N/A

LM2678SDX-5.0

14

NOPB

1

260

Full production

N/A

1K+

$3.13

reel
of
2500

NS
UZXYTT
S0003DB

6 weeks

N/A

LM2678SDX-ADJ

14

STD

NOPB

1

1

260

260

Full production

N/A

1K+

$3.13

reel
of
2500

NS
UZXYTT
S0003EB

6 weeks

15000

LM2678T-12

7

NOPB

1

NA

Full production

N/A

Samples

1K+

$3.13

rail
of
45

NSUZXYTTE#
LM2678
T-12

6 weeks

500

LM2678T-3.3

7

NOPB

1

NA

Full production

N/A

Samples

1K+

$3.13

rail
of
45

NSUZXYTTE#
LM2678
T-3.3

6 weeks

1000

LM2678T-5.0

7

STD

NOPB

1

1

NA

NA

Full production

N/A

Samples

1K+

$3.13

rail
of
45

NSUZXYTTE#
LM2678
T-5.0

6 weeks

500

LM2678T-ADJ

7

STD

NOPB

1

1

NA

NA

Full production

N/A

Samples

1K+

$3.13

rail
of
45

NSUZXYTTE#
LM2678
T-ADJ

6 weeks

500

LM2678S-12

7

STD

NOPB

3

3

235

245

Full production

N/A

Samples

1K+

$3.13

rail
of
45

NSUZXYTTE#
LM2678
S-12

6 weeks

500

LM2678S-3.3

7

STD

NOPB

3

3

235

245

Full production

N/A

Samples

1K+

$3.13

rail
of
45

NSUZXYTTE#
LM2678
S-3.3

6 weeks

500

LM2678S-5.0

7

STD

NOPB

3

3

235

245

Full production

N/A

Samples

1K+

$3.13

rail
of
45

NSUZXYTTE#
LM2678
S-5.0

6 weeks

500

LM2678S-ADJ

7

STD

NOPB

3

3

235

245

Full production

N/A

Samples

1K+

$3.13

rail
of
45

NSUZXYTTE#
LM2678
S-ADJ

6 weeks

2000

LM2678SX-12

7

NOPB

3

245

Full production

N/A

1K+

$3.13

reel
of
500

NSUZXYTTE#
LM2678
S-12

6 weeks

2500

LM2678SX-3.3

7

STD

NOPB

3

3

235

245

Full production

N/A

1K+

$3.13

reel
of
500

NSUZXYTTE#
LM2678
S-3.3

6 weeks

1000

LM2678SX-5.0

7

STD

NOPB

3

3

235

245

Full production

N/A

1K+

$3.13

reel
of
500

NSUZXYTTE#
LM2678
S-5.0

6 weeks

2000

LM2678SX-ADJ

7

STD

NOPB

3

3

235

245

Full production

N/A

1K+

$3.13

reel
of
500

NSUZXYTTE#
LM2678
S-ADJ

6 weeks

1000

Obsolete Parts

Obsolete Part	Alternate Part or Supplier	Source	Last 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-12	LMDMOS	0	15190	0	0	1750000	3	496567278
LM2678S-3.3	LMDMOS	0	15190	0	0	1750000	3	496567278
LM2678S-5.0	LMDMOS	0	15190	0	0	1750000	3	496567278
LM2678S-ADJ	LMDMOS	0	15190	0	0	1750000	3	496567278
LM2678SD-12	LMDMOS	0	15190	0	0	1750000	3	496567278
LM2678SD-3.3	LMDMOS	0	15190	0	0	1750000	3	496567278
LM2678SD-5.0	LMDMOS	0	15190	0	0	1750000	3	496567278
LM2678SD-ADJ	LMDMOS	0	15190	0	0	1750000	3	496567278
LM2678SDX-12	LMDMOS	0	15190	0	0	1750000	3	496567278
LM2678SDX-3.3	LMDMOS	0	15190	0	0	1750000	3	496567278
LM2678SDX-5.0	LMDMOS	0	15190	0	0	1750000	3	496567278
LM2678SDX-ADJ	LMDMOS	0	15190	0	0	1750000	3	496567278
LM2678SX-12	LMDMOS	0	15190	0	0	1750000	3	496567278
LM2678SX-3.3	LMDMOS	0	15190	0	0	1750000	3	496567278
LM2678SX-5.0	LMDMOS	0	15190	0	0	1750000	3	496567278
LM2678SX-ADJ	LMDMOS	0	15190	0	0	1750000	3	496567278
LM2678T-12	LMDMOS	0	15190	0	0	1750000	3	496567278
LM2678T-3.3	LMDMOS	0	15190	0	0	1750000	3	496567278
LM2678T-5.0	LMDMOS	0	15190	0	0	1750000	3	496567278
LM2678T-ADJ	LMDMOS	0	15190	0	0	1750000	3	496567278

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

Title	Size in Kbytes	Date
SimpleSwitcher® DC-DC Converters Design Software	12 Kbytes	11-Jan-2008	View

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Application Notes

Title	Size in Kbytes	Date
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

Title	Size in Kbytes	Date
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
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
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
AN-1229 (Chinese): Application Note 1229 SIMPLE SWITCHER PCB Layout Guidelines	668 Kbytes

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[Information as of 21-Nov-2008]