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LTC1148

LTC1148-3.3/LTC1148-5

High Efficiency Synchronous

Step-Down Switching Regulators

LOAD CURRENT (A)

0.02

80

85

90

100

0.2

2

LTC1148 • TA01

95

LTC1148-5 Efficiency

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FEATURE

DESCRIPTIO

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Ultrahigh Efficiency: Over 95% Possible

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Current-Mode Operation for Excellent Line and Load

Transient Response

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High Efficiency Maintained Over Three Decades of

Output Current

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Low 160

µA Standby Current at Light Loads

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Short-Circuit Protection

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Very Low Dropout Operation: 100% Duty Cycle

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Synchronous FET Switching for High Efficiency

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Adaptive Nonoverlap Gate Drives

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Output Can Be Externally Held High in Shutdown

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Available in 14-Pin Narrow SO Package

The LTC

down switching regulator controllers featuring automatic

Burst Mode

low output currents. These devices drive external comple-

mentary power MOSFETs at switching frequencies up to

250kHz using a constant off-time current-mode architec-

ture providing constant ripple current in the inductor.

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-

and resistance of the inductor and current sense resistor.

The LTC1148 series combines synchronous switching for

maximum efficiency at high currents with an automatic low

current operating mode, called Burst Modeoperation, which

reduces switching losses. Standby power is reduced to only

operation are typically 0mA to 300mA.

For operation up to 48V input, see the LTC1149 and

LTC1159 data sheets and Application Note 54.

Figure 1. High Efficiency Step-Down Converter

APPLICATI

TYPICAL

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

Burst Mode is a trademark of Linear Technology Corporation.

* LTC1148L and LTC1148L-3.3 only.

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APPLICATI

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Notebook and Palmtop Computers

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Portable Instruments

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Battery-Operated Digital Devices

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Cellular Telephones

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DC Power Distribution Systems

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GPS Systems

0V = NORMAL

>1.5V = SHUTDOWN

P-CHANNEL

Si4431DY

+

1

µF

L*

62

µH

0.05

Ω

5V/2A

+

100

µF

SGND

470pF

3300pF

1k

+

390

µF

D1

MBRS140T3

LT1148 • TA01

N-DRIVE

PGND

N-CHANNEL

Si4412DY

P-DRIVE

LTC1148HV-5

SHUTDOWN

1000pF

COILTRONICS CTX62-2-MP

KRL SL-1-C1-0R050J

*

**