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LT1268B/LT1268

7.5A, 150kHz

Switching Regulators

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FEATURE

DESCRIPTIO

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Wide Input Voltage Range: 3.5V to 30V

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Low Quiescent Current: 7mA

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Internal 7.5A Switch

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Very Few External Parts Required

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Self-Protected Against Overloads

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Available in Standard and Surface Mount

5-Pin Packages

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Can Be Externally Synchronized

(See LT1072 Data Sheet)

The LT1268B and LT1268 are monolithic high power

switching regulators. Identical to the popular LT1070,

except for switching frequency (150kHz) and higher

switch current, they can be operated in all standard

switching configurations including buck, boost, flyback,

and inverting. A high current, high efficiency switch is

included on the die along with all oscillator, control, and

protection circuitry. Integration of all functions allows

the LT1268 to be built in standard 5-pin power packages.

This makes it extremely easy to use and provides “bust

proof” operations similar to that obtained with 3-pin

linear regulators.

The LT1268 operate with supply voltages from 3.5V to

30V and draw only 7mA quiescent current. By utilizing

current mode switching techniques, it provides excellent

AC and DC load and line regulation.

The LT1268 use an adaptive anti-sat switch drive to allow

very wide ranging load currents with no loss in efficiency.

An externally activated shutdown mode reduces total

supply current to 100

µA typical for standby operation.

USER NOTE:

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

description of the LT1268B/LT1268. Application circuits are included to show the capability of the

LT1268B/LT1268. 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 LT1268B/LT1268 factoring in the higher switch

current rating and higher operating frequency.

APPLICATI

TYPICAL

Boost Regulator with 5.3V

±1% Output

LOAD CURRENT (A)

0

80

90

4

LT1268 • TA02

70

60

1

2

3

100

Efficiency of 5.3V Boost Converter

LT1268B

L1

8

µH, 5A*

D1

MBR1035

D2, D3

†

1N4001

C2

0.068

C3

390

µF

16V

R1

4.043k

0.1%

R2

1.24k

0.1%

R3

220

Ω

FB

GND

CASE

L2

2

µH, 5A**

C1

220

µF

16V

+

+

C4

390

µF

16V

5.3V ±1%

3.75A

4.7V TO

5.3V

LT1268 • TA01

COILTRONICS CTX8-5-52

COILTRONICS CTX2-5-52

OPTIONAL. D2 AND D3 ARE USED TO INCREASE

UNDERVOLTAGE LOCKOUT FROM 2.7V TO

≈4V.

*

**

†

+

C5

0.02

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APPLICATI

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High Efficiency Boost Converter

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PC Power Supply with Multiple Outputs

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Battery Upconverter

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Negative-to-Positive Converter