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LTC1753

1753fa

5-Bit Programmable

Synchronous Switching

Regulator Controller for

Pentium

The LTC

regulator controller optimized for 5V input to a digitally

programmable 1.3V-3.5V output. The internal 5-bit DAC

programs the output voltage from 1.3V to 2.05V in 50mV

increments and from 2.1V to 3.5V in 100mV increments. The

precision internal reference and an internal feedback system

provide an output accuracy of

±1.5% at room temperature

and typically

±2% over temperature, load current and line

voltage shifts. The LTC1753 uses a synchronous switching

architecture with two external N-channel output devices,

providing high efficiency and eliminating the need for a high

power, high cost P-channel device. Additionally, it senses the

output current across the on-resistance of the upper N-

channel FET, providing an adjustable current limit without an

external low value sense resistor.

The LTC1753 free-runs at 300kHz and can be synchronized

to a faster external clock if desired. It provides a phase lead

compensation scheme and under harsh loading conditions,

the PWM duty cycle can be momentarily forced to 0% or

100% to reduce the output voltage recovery time.

Figure 1. 5V to 1.3V-3.5V Supply Application

, 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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5-Bit Digitally Programmable 1.3V to 3.5V Fixed

Output Voltage, VRM 8.4 Compliant

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Fast Transient Response: 0% to 100% Duty Cycle

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Phase Lead Compensation for Remote Sensing

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Overtemperature Protection

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Flags for Power Good and Overvoltage Fault

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19A Output Current Capability from a 5V Supply

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Dual N-Channel MOSFET Synchronous Driver

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Initial Output Accuracy:

±1.5%

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Excellent Output Accuracy:

±2% Typ Over Line,

Load and Temperature Variations

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High Efficiency: Over 95% Possible

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Adjustable Current Limit Without External Sense

Resistors

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Available in 2O-Lead SSOP and SW Packages

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Power Supply for Pentium

ALPHA and PA-RISC Microprocessors

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High Power 5V to 1.3V-3.5V Regulators

PWRGD

FAULT

VID0 TO VID4

OUTEN

COMP

SS

SGND

GND

SENSE

10

µF

Q1*

20

Ω

Q2*

Q2A*

Q1A*

0.1

µF

12V

5V

1.3

µH

18A

LTC1753

G1

+

1

µF

NC

1753 F01

4700pF

15k

600

Ω

5.6k

5.6k

0.1

µF

+

0.1

µF

10

µF

1200

µF

× 4

1.3V TO

3.5V

14A

2700

µF

× 5

+

C1

150pF

+

5

* SILICONIX SUD50N03-10

** SANYO 10MV1200GX

CPU

G2

DESCRIPTIO

FEATURES

APPLICATIO S

TYPICAL APPLICATIO