LINEAR TECHNOLOGY LTC1703 User's Manual

LTC1703

Dual 550k Hz Synchronous 2-Phase Switching Regulator Controller with 5-Bit VID

FEATURES DESCRIPTIO Side 1 Output Is Compliant with Intel Mobile The LTC®1703 is a dual switching regulator controller opti- VID Specifications (Includes 5-Bit DAC) mized for high efficiency with low input voltages. It includes 0.9V to 2.0V Output Voltage with 25m V/50m V Steps two complete, on-chip, independent switching regulator

Two Sides Run Out-of-Phase to Minimize CIN controllers. Each is designed to drive a pair of external Precision Internal 0.8V ±1% Reference N-channel MOSFET devices in a voltage mode feedback,

Two Independent PWM Controllers in One Package synchronous buck configuration. The LTC1703 includes

All N-Channel External MOSFET Architecture digital output voltage adjustment on side 1 that conforms to No External Current Sense Resistor the Intel Mobile VID specification. It uses a constant- 550k Hz Switching Frequency Minimizes External frequency, true PWM design switching at 550k Hz, minimiz- Component Size ing external component size and cost and optimizing load Very Fast Transient Response transient performance. The synchronous buck architecture Up to 25A Output Current per Channel automatically shifts to discontinuous and then to Burst Low Shutdown Current: < 100µA Mode® operation as the output load decreases, ensuring

Small 28-Pin SSOP Package maximum efficiency over a wide range of load currents.

The LTC1703 features an onboard reference trimmed to 1%

APPLICATIO S

and delivers better than 1.5% regulation at the converter Mobile Pentium® III Processor Systems outputs. An optional latching FAULT mode protects the load Microprocessor Core and I/O Supplies if the output rises 15% above the intended voltage. Each Multiple Logic Supply Generator channel can be enabled independently; with both channels High Efficiency Power Conversion disabled, the LTC1703 shuts down and supply current drops , LTC and LT are registered trademarks of Linear Technology Corporation. below 100µA.

Burst Mode is a registered trademark of Linear Technology Corporation. All other trademarks are the property of their respective owners.

TYPICAL APPLICATIO

Dual Output Mobile Pentium III Processor Supply

4.5V TO 5.5V

DCP2 CIN

1µF QT2 150µF

MBR0520LT1 MBR0520LT1

QT1 L2

VOUT1 1µH 2.2µH

LTC1703 VOUT2

TO 2V PVCC IMAX2

15A QB1BQB1ACOUT1 CCP1 CCP2 C32

BOOST1 BOOST2

1µF 1µF COUT2 2200p F

180µF BG1 BG2 QB2

TG1 TG2 R32

× 6 RIMAX2 4V 10.2k 10Ω

SW1 SW2 20k 0.1%

RIMAX1,18.7k

GND IMAX1 PGND

FCB FAULT RB2 GND 11.5k

RUN/SS1 RUN/SS2

CSS1 GND

COMP1 COMP2

SGND FB2

220p F FB1 VCC

SENSE VID4

R31, 10k VID0 VID3 1703 TA01

VID1 VID2 1µF

L1: MURATA LQT12535C1R5N12

L2: COILTRONICS UP2B-2R2

QT1, QB1A, QB1B: INTERNATIONAL RECTIFIER IRF7811

QT2, QB2: 1/2 FAIRCHILD NDS8926

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