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LTC1430A

High Power Step-Down

Switching Regulator Controller

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FEATURE

DESCRIPTIO

The LTC

regulator controller optimized for 5V to 1.xV-3.xV applica-

tions. It includes a precision internal reference and an

internal feedback system that can provide output regula-

tion of

±1%overtemperature,loadcurrentandlinevoltage

shifts. The LTC1430A uses a synchronous switching archi-

tecture with two N-channel output devices, eliminating the

need for a high power, high cost P-channel device. Addi-

tionally, it senses output current across the drain-source

resistance of the upper N-channel FET, providing an

adjustable current limit without an external low value sense

resistor.

The LTC1430A includes a fixed frequency PWM oscillator

for low output ripple under virtually all operating condi-

tions. The 200kHz free-running clock frequency can be

externally adjusted from 100kHz to above 500kHz. The

LTC1430A’s maximum duty cycle is typically 93.5% com-

pared to 88% for the LTC1430. This permits 3.3V to 2.xV

conversion using a low power 5V supply. The LTC1430A

features low 350

µA quiescent current, allowing greater

than 90% efficiency operation in converter designs from

1A to greater than 50A output current. Shutdown mode

drops the LTC1430A supply current to 1

µA.

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High Power 5V to 1.xV-3.xV Switching Controller:

Can Exceed 10A Output

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Maximum Duty Cycle > 90% Permits 3.3V to 2.xV

Conversion Using a Low Power 5V Supply

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All N-Channel External MOSFETs

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Fixed Frequency Operation—Small L

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Excellent Output Regulation:

±1% Over Line, Load

and Temperature Variations

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High Efficiency: Over 95% Possible

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No Low Value Sense Resistor Needed

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Outputs Can Drive External FETs with Up to

10,000pF Gate Capacitance

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Quiescent Current: 350

µA Typ, 1µA in Shutdown

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Fast Transient Response

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Adjustable or Fixed 3.3V Output

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Available in 8-Lead SO and 16-Lead GN

and SO Packages

APPLICATI

TYPICAL

Efficiency

Typical 5V to 3.3V, 10A Application

+

220

µF

×4

330

µF

×6

+

+

+

2.7

µH/15A

FREQSET

SHDN

COMP

SS

PGND

GND

G1

G2

NC

1430 TA01

SHUTDOWN

FB

NC

Q1A, Q1B, Q2: MOTOROLA MTD20N03HL

LTC1430A

16k

100

Ω

7.5k

4700pF

C1

220pF

MBR0530T1

1k

0.1

µF

1

µF

0.01

µF

0.1

µF

4.7

µF

0.1

µF

3.3V

10A

Q1A, Q1B

2 IN PARALLEL

Q2

5V

LOAD CURRENT (A)

40

70

100

90

80

50

60

10

1430 TA02

0.1

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

Pentium is a registered trademark of Intel Corporation.

AMD-K6 is a registered trademark of Advanced Micro Devices, Inc.

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APPLICATI

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Power Supply for Pentium

Microprocessors

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High Power 5V to 3.xV Regulators

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Local Regulation for Dual Voltage Logic Boards

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Low Voltage, High Current Battery Regulation