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LT1070/LT1071

FEATURES

APPLICATIO S

DESCRIPTIO

TYPICAL APPLICATIO

5A and 2.5A High Efficiency

Switching Regulators

s

Wide Input Voltage Range: 3V to 60V

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Low Quiescent Current: 6mA

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Internal 5A Switch (2.5A for LT1071)

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Very Few External Parts Required

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Self Protected Against Overloads

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Operates in Nearly All Switching Topologies

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Shutdown Mode Draws Only 50

µA Supply Current

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Flyback Regulated Mode Has Fully Floating Outputs

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Comes in Standard 5-Pin TO-220 Package

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Can be Externally Synchronized (Consult Factory)

The LT

ing regulators. They can be operated in all standard switch-

ing configurations including buck, boost, flyback, for-

ward, inverting and “Cuk”. A high current, high efficiency

switch is included on the die along with all oscillator,

control and protection circuitry. Integration of all func-

tions allows the LT1070/LT1071 to be built in a standard

5-pin T0-220 power package. This makes it extremely

easy to use and provides “bust proof” operation similar to

that obtained with 3-pin linear regulators.

The LT1070/LT1071 operate with supply voltages from 3V

to 60V, and draw only 6mA quiescent current. They can

deliver load power up to 100W with no external power

devices. By utilizing current mode switching techniques,

they provide excellent AC and DC load and line regulation.

The LT1070/LT1071 have many unique features not found

even on the vastly more difficult to use low power control

chips presently available. They use adaptive antisat switch

drive to allow very wide ranging load currents with no loss

in efficiency. An externally activated shutdown mode

reduces total supply current to 50

µA typical for standby

operation. Totally isolated and regulated outputs can be

generated by using the optional “flyback regulation mode”

built into the LT1070/LT1071, without the need for

optocouplers or extra transformer windings.

USER NOTE:

This data sheet is only intended to provide specifications, graphs and a general functional

description of the LT1070/LT1071. Application circuits are included to show the capability of the

LT1070/LT1071. A complete design manual (AN19) should be obtained to assist in developing new

designs. This manual contains a comprehensive discussion of both the LT1070 and the external

components used with it, as well as complete formulas for calculating the values of these

components. The manual can also be used for the LT1071 by factoring in the lower switch current

rating. A second Application Note, AN25, which details off-line applications is available.

+

R1

10.7k

1%

R2

1.24k

1%

1070/71 TA01

12V

1A

R3

1k

C1

1

µF

C2

1000

µF

+

C3*

100

µF

L1**

150

µH

D1

5V

LT1070

GND

FB

C3

100

µF

L2

10

µH

OUTPUT

FILTER

*

**

REQUIRED IF INPUT LEADS

≥ 2"

PULSE ENGINEERING 92113

INPUT VOLTAGE (V)

0

60

80

100

40

1070/71 TA02

40

20

0

10

20

30

50

BOOST

BUCK/BOOST

FLYBACK

ISOLATED

BUCK/BOOST

SPECIAL TOPOLOGIES DELIVER MORE POWER

DIVIDE VERTICAL POWER SCALE BY 2 FOR LT1071

*

**

Maximum Output Power*

Boost Converter (5V to 12V)

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Logic Supply 5V at 10A

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5V Logic to

±15V Op Amp Supply

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Off-Line Converter Up to 200W

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Battery Upconverter

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Power Inverter (+ to –) or (– to +)

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Fully Floating Multiple Outputs

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For Lower Current Applications, See the LT1072

, LTC and LT are registered trademarks of Linear Technology Corporation.