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LTC1266

LTC1266-3.3/LTC1266-5

Synchronous Regulator

Controller for

N- or P-Channel MOSFETs

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FEATURE

DESCRIPTIO

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Ultra-High Efficiency: Over 95% Possible

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Drives N-Channel MOSFET for High Current or

P-Channel MOSFET for Low Dropout

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Pin Selectable Burst Mode Operation

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1% Output Accuracy (LTC1266A)

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Pin Selectable Phase of Topside Driver for Boost

or Step-Down Operation

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On-Chip Low-Battery Detector

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High Efficiency Maintained over Large Current Range

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Low 170

µA Standby Current at Light Loads

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Current Mode Operation for Excellent Line and Load

Transient Response

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Short Circuit Protection

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Synchronous Switching with Nonoverlaping Gate Drives

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Available in 16-Pin Narrow SO Package

The LTC

regulator controllers featuring automatic Burst Mode

TM

operation to maintain high efficiencies at low output

currents. These devices drive external power MOSFETs at

switching frequencies up to 400kHz using a constant off-

time current mode architecture providing constant ripple

current in the inductor. They can drive either an N-channel

or a P-channel topside MOSFET.

The operating current level is user-programmable via an

external current sense resistor. Wide input supply range

allows operation from 3.5V to 18V (20V maximum).

Constant off-time architecture provides low dropout regu-

(when using the P-channel) and the resistance of the

inductor and current sense resistor.

The LTC1266 series combines synchronous switching for

maximum efficiency at high currents with an automatic

low current operating mode, called Burst Mode operation,

which reduces switching losses. Standby power is re-

in Burst Mode operation are typically 0mA to 500mA.

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

Burst Mode is a trademark of Linear Technology Corporation.

Figure 1. High Efficiency Step-Down Converter

LTC1266-3.3 Efficiency

LOAD CURRENT (A)

0.01

80

85

90

95

100

0.1

5

1

LTC1266 • TA02

0V = NORMAL

>1.5V = SHUTDOWN

N-CHANNEL

Si9410

+

100

µF

×2

L*

5

µH

D2

MBR0530T1

0.02

Ω

100k

3.3V

5A

LOW BAT OUT

4V TO 9V

SGND

180pF

3300pF

470

Ω

+

330

µF

× 2

D1

MBRS130LT3

LTC1266 • TA01

BDRIVE

BINH

PGND

N-CHANNEL

Si9410

PINV

LTC1266-3.3

SHDN

TDRIVE

1000pF

0.1

µF

*COILTRONICS CTXO212801

LOW BAT IN

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Notebook and Palmtop Computers

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Portable Instruments

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Cellular Telephones

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DC Power Distribution Systems

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GPS Systems

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APPLICATI

APPLICATI

TYPICAL