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

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

Overview

Diagrams

Parametrics

Documents

Order

Packaging

Tools

Reliability

Obsolete Versions

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

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.

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® LM2678

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

LM22678▲ 500kHz, Adjustable Switching Frequency Up To 1MHz

Typical Application click for larger image

Block Diagram click for larger image

Typical Performance *click for larger image

Parameters / Values	LM2678	LM22678
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	Yes	Yes
PowerGood / Error Flag	No	No
SoftStart	No	No
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	Internal Type 3 compensation, 2% output voltage accuracy, SIMPLE SWITCHER regulator	500 kHz Switching Frequency
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
Synchronous Rectification	No	No

Datasheets
Title Size Date Other
Language

LM2678 SIMPLE SWITCHER High Efficiency 5A Step-Down Voltage Regulator 670
Kbytes 1-May-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

LM2678S-12/NOPB

LM2678S-12

RoHS Status

TO-263

Full production
Lead Time: 6 weeks

Distributor	Region	Qty
ARROW	Worldwide	16
AVNET-EM	Worldwide	40
DIGI-KEY	Worldwide	323
MOUSER	Worldwide	122
RS COMPONENTS	Worldwide	26
TAYLOR	Americas	23

$3.25 each at 1K+ pcs

rail
of
45

LM2678S-3.3/NOPB

LM2678S-3.3

RoHS Status

TO-263

Full production
Lead Time: 6 weeks

Distributor	Region	Qty
ARROW	Worldwide	495
AVNET-EM	Worldwide	45
DIGI-KEY	Worldwide	286
MOUSER	Worldwide	135
NEWARK	Americas	285
RS COMPONENTS	Worldwide	39
TAYLOR	Americas	495

$3.25 each at 1K+ pcs

rail
of
45

LM2678S-5.0/NOPB

LM2678S-5.0

RoHS Status

TO-263

Full production
Lead Time: 6 weeks

Distributor	Region	Qty
ARROW	Worldwide	1125
AVNET-EM	Worldwide	295
DIGI-KEY	Worldwide	410
MOUSER	Worldwide	67
NEWARK	Americas	564
RS COMPONENTS	Worldwide	51
TAYLOR	Americas	1125

$3.25 each at 1K+ pcs

rail
of
45

LM2678S-ADJ/NOPB

LM2678S-ADJ

RoHS Status

TO-263

Full production
Lead Time: 6 weeks

Distributor	Region	Qty
ARROW	Worldwide	2158
AVNET-EM	Worldwide	99
DIGI-KEY	Worldwide	1147
FARNELL	Europe and Asia	425
MOUSER	Worldwide	13
RS COMPONENTS	Worldwide	46
TAYLOR	Americas	1858

$3.25 each at 1K+ pcs

rail
of
45

LM2678SD-12/NOPB

LM2678SD-12

RoHS Status

LLP

Full production
Lead Time: 6 weeks

Distributor		Region	Qty
DIGI-KEY		Worldwide	621
MOUSER		Worldwide	220

$3.25 each at 1K+ pcs

reel
of
250

LM2678SD-3.3/NOPB

LM2678SD-3.3

RoHS Status

LLP

Full production
Lead Time: 6 weeks

Distributor	Region	Qty
ARROW	Worldwide	225
AVNET-EM	Worldwide	250
DIGI-KEY	Worldwide	352
MOUSER	Worldwide	220
TAYLOR	Americas	225

$3.25 each at 1K+ pcs

reel
of
250

LM2678SD-5.0/NOPB

LM2678SD-5.0

RoHS Status

LLP

Full production
Lead Time: 6 weeks

Distributor	Region	Qty
ARROW	Worldwide	500
AVNET-EM	Worldwide	500
DIGI-KEY	Worldwide	1412
MOUSER	Worldwide	250
NEWARK	Americas	262
TAYLOR	Americas	500
TECHMOSA	Asia Pacific	500

$3.25 each at 1K+ pcs

reel
of
250

LM2678SD-ADJ/NOPB

LM2678SD-ADJ

RoHS Status

LLP

Full production
Lead Time: 6 weeks

Distributor	Region	Qty
ARROW	Worldwide	250
DIGI-KEY	Worldwide	1280
MOUSER	Worldwide	235
NEWARK	Americas	59
TAYLOR	Americas	250

$3.25 each at 1K+ pcs

reel
of
250

LM2678SDX-12

RoHS Status

LLP

Full production
Lead Time: 16 weeks

Distributor		Region	Qty
DIGI-KEY		Worldwide	0

$3.25 each at 1K+ pcs

reel
of
2500

LM2678SDX-3.3

RoHS Status

LLP

Full production
Lead Time: 16 weeks

Distributor		Region	Qty
DIGI-KEY		Worldwide	0

$3.25 each at 1K+ pcs

reel
of
2500

LM2678SDX-5.0/NOPB

LM2678SDX-5.0

RoHS Status

LLP

Full production
Lead Time: 6 weeks

Distributor		Region	Qty
DIGI-KEY		Worldwide	0

$3.25 each at 1K+ pcs

reel
of
2500

LM2678SDX-ADJ/NOPB

LM2678SDX-ADJ

RoHS Status

LLP

Full production
Lead Time: 6 weeks

Distributor		Region	Qty
DIGI-KEY		Worldwide	0

$3.25 each at 1K+ pcs

reel
of
2500

LM2678SX-12/NOPB

RoHS Status

TO-263

Full production
Lead Time: 6 weeks

Distributor		Region	Qty
DIGI-KEY		Worldwide	0

$3.25 each at 1K+ pcs

reel
of
500

LM2678SX-3.3/NOPB

LM2678SX-3.3

RoHS Status

TO-263

Full production
Lead Time: 6 weeks

Distributor	Region	Qty
ARROW	Worldwide	1000
AVNET-EM	Worldwide	500
DIGI-KEY	Worldwide	0
MOUSER	Worldwide	470
TAYLOR	Americas	1000

$3.25 each at 1K+ pcs

reel
of
500

LM2678SX-5.0/NOPB

LM2678SX-5.0

RoHS Status

TO-263

Full production
Lead Time: 6 weeks

Distributor	Region	Qty
AITG	Asia Pacific	1001
ARROW	Worldwide	1000
AVNET-EM	Worldwide	500
DIGI-KEY	Worldwide	0
MOUSER	Worldwide	500
RSL MICRO	Asia Pacific	2500
TAYLOR	Americas	1000

$3.25 each at 1K+ pcs

reel
of
500

LM2678SX-ADJ/NOPB

LM2678SX-ADJ

RoHS Status

TO-263

Full production
Lead Time: 6 weeks

Distributor	Region	Qty
ARROW	Worldwide	500
CEAC	Asia Pacific	3000
DIGI-KEY	Worldwide	0
MOUSER	Worldwide	500
RSL MICRO	Asia Pacific	1000
TAYLOR	Americas	4000

$3.25 each at 1K+ pcs

reel
of
500

LM2678T-12/NOPB

LM2678T-12

RoHS Status

TO-220

Full production
Lead Time: 6 weeks

Distributor	Region	Qty
ARROW	Worldwide	175
AVNET-EM	Worldwide	146
DIGI-KEY	Worldwide	45
FARNELL	Europe and Asia	359
MOUSER	Worldwide	121
NEWARK	Americas	73
RS COMPONENTS	Worldwide	13
TAYLOR	Americas	175

$3.25 each at 1K+ pcs

rail
of
45

LM2678T-3.3/NOPB

LM2678T-3.3

RoHS Status

TO-220

Full production
Lead Time: 6 weeks

Distributor	Region	Qty
AVNET-EM	Worldwide	135
DIGI-KEY	Worldwide	56
MOUSER	Worldwide	115
RS COMPONENTS	Worldwide	3

$3.25 each at 1K+ pcs

rail
of
45

LM2678T-5.0/NOPB

LM2678T-5.0

RoHS Status

TO-220

Full production
Lead Time: 6 weeks

Distributor	Region	Qty
ARROW	Worldwide	2522
AVNET-EM	Worldwide	47
DIGI-KEY	Worldwide	1878
MOUSER	Worldwide	127
NEWARK	Americas	64
RS COMPONENTS	Worldwide	25
TAYLOR	Americas	2522

$3.25 each at 1K+ pcs

rail
of
45

LM2678T-ADJ/NOPB

LM2678T-ADJ

RoHS Status

TO-220

Full production
Lead Time: 6 weeks

Distributor	Region	Qty
ARROW	Worldwide	624
BRITESTONE	South Korea	3645
DIGI-KEY	Worldwide	1711
FARNELL	Europe and Asia	539
MOUSER	Worldwide	184
NEWARK	Americas	177
RS COMPONENTS	Worldwide	21
TAYLOR	Americas	639

$3.25 each at 1K+ pcs

rail
of
45

Obsolete Versions

Obsolete Part Alternate Part or Supplier Source Last Time Buy Date

LM2678LD-12
NONE
NONE
30 Jan 2004

LM2678LD-3.3
NONE
NONE
30 Jan 2004

LM2678LD-5.0
NONE
NONE
30 Jan 2004

LM2678LD-ADJ
NONE
NONE
30 Jan 2004

LM2678LDX-12
NONE
NONE
30 Jan 2004

LM2678LDX-3.3
NONE
NONE
30 Jan 2004

LM2678LDX-5.0
NONE
NONE
30 Jan 2004

LM2678LDX-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 LM2678.

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 LM2678 is located at RoHS Status.

Part Number(s) (NSID)	Weight (milligrams)	Type	Pins	MSL Rating	Peak Reflow	RoHS Status	CAD Symbols	Models	Package Marking Format
LM2678S-12/NOPB LM2678S-12	1608.332 1609.822	TO-263	7	3 3	245 235	Detail	Download	N/A	NSUZXYTTE# LM2678 S-12
LM2678S-3.3/NOPB LM2678S-3.3	1608.332 1609.822	TO-263	7	3 3	245 235	Detail	Download	N/A	NSUZXYTTE# LM2678 S-3.3
LM2678S-5.0/NOPB LM2678S-5.0	1608.332 1609.822	TO-263	7	3 3	245 235	Detail	Download	N/A	NSUZXYTTE# LM2678 S-5.0
LM2678S-ADJ/NOPB LM2678S-ADJ	1608.332 1609.822	TO-263	7	3 3	245 235	Detail	Download	N/A	NSUZXYTTE# LM2678 S-ADJ
LM2678SD-12/NOPB LM2678SD-12	94.439 94.76	LLP	14	1 1	260 260	Detail	Download	N/A	NS UZXYTT S0003BB
LM2678SD-3.3/NOPB LM2678SD-3.3	94.439 94.76	LLP	14	1 1	260 260	Detail	Download	N/A	NS UZXYTT S0003CB
LM2678SD-5.0/NOPB LM2678SD-5.0	94.439 94.76	LLP	14	1 1	260 260	Detail	Download	N/A	NS UZXYTT S0003DB
LM2678SD-ADJ/NOPB LM2678SD-ADJ	94.439 94.76	LLP	14	1 1	260 260	Detail	Download	N/A	NS UZXYTT S0003EB
LM2678SDX-12	94.76	LLP	14	1	260	Detail	Download	N/A	NS UZXYTT S0003BB
LM2678SDX-3.3	94.76	LLP	14	1	260	Detail	Download	N/A	NS UZXYTT S0003CB
LM2678SDX-5.0/NOPB LM2678SDX-5.0	94.439 94.76	LLP	14	1 1	260 260	Detail	Download	N/A	NS UZXYTT S0003DB
LM2678SDX-ADJ/NOPB LM2678SDX-ADJ	94.439 94.76	LLP	14	1 1	260 260	Detail	Download	N/A	NS UZXYTT S0003EB
LM2678SX-12/NOPB	1608.332	TO-263	7	3	245	Detail	Download	N/A	NSUZXYTTE# LM2678 S-12
LM2678SX-3.3/NOPB LM2678SX-3.3	1608.332 1609.822	TO-263	7	3 3	245 235	Detail	Download	N/A	NSUZXYTTE# LM2678 S-3.3
LM2678SX-5.0/NOPB LM2678SX-5.0	1608.332 1609.822	TO-263	7	3 3	245 235	Detail	Download	N/A	NSUZXYTTE# LM2678 S-5.0
LM2678SX-ADJ/NOPB LM2678SX-ADJ	1608.332 1609.822	TO-263	7	3 3	245 235	Detail	Download	N/A	NSUZXYTTE# LM2678 S-ADJ
LM2678T-12/NOPB LM2678T-12	1846.782 1858.793	TO-220	7	1 1	NA NA	Detail	Download	N/A	NSUZXYTTE# LM2678 T-12
LM2678T-3.3/NOPB LM2678T-3.3	1846.782 1858.793	TO-220	7	1 1	NA NA	Detail	Download	N/A	NSUZXYTTE# LM2678 T-3.3
LM2678T-5.0/NOPB LM2678T-5.0	1846.782 1858.793	TO-220	7	1 1	NA NA	Detail	Download	N/A	NSUZXYTTE# LM2678 T-5.0
LM2678T-ADJ/NOPB LM2678T-ADJ	1846.782 1858.793	TO-220	7	1 1	NA NA	Detail	Download	N/A	NSUZXYTTE# LM2678 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 LM2678.

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 LM2678 is located at RoHS Status.

Design Tools
Title Size Date

SimpleSwitcher® DC-DC Converters Design Software

CAD Symbols and Models
Download LM2678 CAD Symbols

Models
N/A

Reliability Metrics

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

LM2678S-12 LMDMOS 0 18295 0 0 2650000 2 751944735

LM2678S-3.3 LMDMOS 0 18295 0 0 2650000 2 751944735

LM2678S-5.0 LMDMOS 0 18295 0 0 2650000 2 751944735

LM2678S-ADJ LMDMOS 0 18295 0 0 2650000 2 751944735

LM2678SD-12 LMDMOS 0 18295 0 0 2650000 2 751944735

LM2678SD-3.3 LMDMOS 0 18295 0 0 2650000 2 751944735

LM2678SD-5.0 LMDMOS 0 18295 0 0 2650000 2 751944735

LM2678SD-ADJ LMDMOS 0 18295 0 0 2650000 2 751944735

LM2678SDX-12 LMDMOS 0 18295 0 0 2650000 2 751944735

LM2678SDX-3.3 LMDMOS 0 18295 0 0 2650000 2 751944735

LM2678SDX-5.0 LMDMOS 0 18295 0 0 2650000 2 751944735

LM2678SDX-ADJ LMDMOS 0 18295 0 0 2650000 2 751944735

LM2678SX-12 LMDMOS 0 18295 0 0 2650000 2 751944735

LM2678SX-3.3 LMDMOS 0 18295 0 0 2650000 2 751944735

LM2678SX-5.0 LMDMOS 0 18295 0 0 2650000 2 751944735

LM2678SX-ADJ LMDMOS 0 18295 0 0 2650000 2 751944735

LM2678T-12 LMDMOS 0 18295 0 0 2650000 2 751944735

LM2678T-3.3 LMDMOS 0 18295 0 0 2650000 2 751944735

LM2678T-5.0 LMDMOS 0 18295 0 0 2650000 2 751944735

LM2678T-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 LM2678.

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 LM2678 is located at RoHS Status.

[Information as of 7-Feb-2012]

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