1

LTC1159

LTC1159-3.3/LTC1159-5

s

Operation from 4V to 40V Input Voltage

s

Ultrahigh Efficiency: Up to 95%

s

20

s

High Efficiency Maintained Over Wide Current Range

s

Current Mode Operation for Excellent Line and Load

Transient Response

s

Very Low Dropout Operation: 100% Duty Cycle

s

Short-Circuit Protection

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Synchronous FET Switching for High Efficiency

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Adaptive Non-Overlap Gate Drives

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Available in SSOP and SO Packages

The LTC

switching regulator controllers featuring automatic Burst

Mode

output currents. These devices drive external complemen-

tary power MOSFETs at switching frequencies up to 250kHz

using a constant off-time current-mode architecture.

A separate pin and on-board switch allow the MOSFET

driver power to be derived from the regulated output

voltage providing significant efficiency improvement when

operating at high input voltages. The constant off-time

current-mode architecture maintains constant ripple cur-

rent in the inductor and provides excellent line and load

transient response. The output current level is user pro-

grammable via an external current sense resistor.

The LTC1159 automatically switches to power saving

Burst Mode operation when load current drops below

approximately 15% of maximum current. Standby current

is only 300

µA while still regulating the output and shut-

down current is a low 20

µA.

High Efficiency Synchronous

Step-Down Switching Regulators

s

Step-Down and Inverting Regulators

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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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Industrial Power Distribution

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Avionics Systems

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Telecom Power Supplies

Figure 1. High Efficiency Step-Down Regulator

LOAD CURRENT (A)

0.02

60

70

80

100

0.2

2

LTC1159 • TA01

90

FIGURE 1 CIRCUIT

LTC1159-5 Efficiency

0.15

µF

CAP

P-DRIVE

LTC1159-5

SHDN1

S-GND

P-GATE

SHDN2

P-GND

N-GATE

0.01

µF

Si9410DY

0.1

µF

1N4148

Si9435DY

D1

MBRS140T3

L*

33

µH

0.05

Ω

5V/2A

220

µF

100

µF

100V

3.3

µF

0V = NORMAL

>2V = SHUTDOWN

3300pF

300pF

1k

LTC1159 • F01

*COILTRONICS CTX33-4-MP

+

+

+

4

3

2

1

Burst Mode is a trademark of Linear Technology Corporation.

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

DESCRIPTIO

FEATURES

APPLICATIO S

TYPICAL APPLICATIO