LM2678S-12 datasheet(1/23 Pages) NSC | SIMPLE SWITCHER High Efficiency 5A Step-Down Voltage Regulator

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LM2678

SIMPLE SWITCHER® High Efficiency 5A Step-Down

Voltage Regulator

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 characteris-

tics. 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 adjust-

able 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 in-

ductors 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, cur-

rent 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% toler-

ance. The clock frequency is controlled to within a ±11% tol-

erance.

Features

Efficiency up to 92%

Simple and easy to design with (using off-the-shelf

external components)

120 m

Ω DMOS output switch

3.3V, 5V and 12V fixed output and adjustable (1.2V to

37V ) versions

50µA standby current when switched OFF

n ±

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

Applications

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

switching regulators

Efficient system pre-regulator for linear voltage

regulators

Battery chargers

Typical Application

SIMPLE SWITCHER® is a registered trademark of National Semiconductor Corporation.

DS100886-3

March 2000

DS100886

Part Number	Components Description	Html View	Manufacturer
LM2676	SIMPLE SWITCHER High Efficiency 3A Step-Down Voltage Regulator	1 2 3 4 5 More	National Semiconductor
LM2677	SIMPLE SWITCHER High Efficiency 5A Step-Down Voltage Regulator with Sync	1 2 3 4 5 More	National Semiconductor
LM2678	SIMPLE SWITCHER High Efficiency 5A Step-Down Voltage Regulator	1 2 3 4 5 More	National Semiconductor
LM2670	SIMPLE SWITCHER High Efficiency 3A Step-Down Voltage Regulator with Sync	1 2 3 4 5 More	National Semiconductor
LM2671	SIMPLE SWITCHER Power Converter High Efficiency 500mA Step-Down Voltage Regulator with Features	1 2 3 4 5 More	National Semiconductor
LM2672	SIMPLE SWITCHER Power Converter High Efficiency 1A Step-Down Voltage Regulator with Features	1 2 3 4 5 More	National Semiconductor
LM2674	SIMPLE SWITCHER Power Converter High Efficiency 500 mA Step-Down Voltage Regulator	1 2 3 4 5 More	National Semiconductor
LM2675	SIMPLE SWITCHER Power Converter High Efficiency 1A Step-Down Voltage Regulator	1 2 3 4 5 More	National Semiconductor
LM2673	SIMPLE SWITCHER 3A Step-Down Voltage Regulator with Adjustable Current Limit	1 2 3 4 5 More	National Semiconductor
LM2590HV	SIMPLE SWITCHER Power Converter 150 kHz 1A Step-Down Voltage Regulator with Features	1 2 3 4 5 More	National Semiconductor

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