LINEAR TECHNOLOGY LTC3709 Fast 2-Phase, No RSENSE Synchronous DC DC Controller with Tracking Sequencing

LTC3709 TM,

Fast 2-Phase, No RSENSE POW ER LOSS (W

Synchronous DC/DC Controller with Tracking/Sequencing

FEATURES DESCRIPTIO

Poly Phase® Valley Current Mode Controller The LTC®3709 is a single output, dual phase, synchronous Synchronizable to an External Clock with PLL step-down switching regulator. The controller uses a Coincident or Ratiometric Tracking constant on-time, valley current control architecture to Sense Resistor Optional deliver very low duty cycles without requiring a sense 2% to 90% Duty Cycle at 200k Hz resistor. Operating frequency is selected by an external t ON(MIN) < 100ns resistor and is compensated for variations in input supply True Remote Sensing Differential Amplifier voltage. An internal phase-lock loop allows the LTC3709 High Efficiency at Both Light and Heavy Loads to be synchronized to an external clock.

Power Good Output Voltage Monitor

A TRACK pin is provided for tracking or sequencing the

0.6V ±1% Reference

output voltage among several LTC3709 chips or an

Adjustable Current Limit

LTC3709 and other DC/DC regulators. Soft-start is ac-

Programmable Soft-Start and Operating Frequency

complished using an external timing capacitor.

Output Overvoltage Protection

Optional Short-Circuit Shutdown Timer Fault protection is provided by an output overvoltage com- Available in 32-Lead (5mm × 5mm) QFN and 36-Lead parator and an optional short-circuit shutdown timer. The SSOP Packages current limit level is user programmable. A wide supply

EF FI CI EN CY

range allows voltages as high as 31V to step down as low APPLICATIO S as 0.6V. , LTC and LT are registered trademarks of Linear Technology Corporation. No RSENSE is

Notebook Computers a trademark of Linear Technology Corporation. Poly Phase is a registered trademark of

Linear Technology Corporation. All other trademarks are the property of their respective

Power Supply for DSP, ASIC, Graphic Processors

owners. Protected by U.S. Patents including 5481178, 6476589, 6144194, 5847554, 6177678, 6304066, 6580258, 6674274, 6462525, 6593724.

TYPICAL APPLICATIO High Efficiency Dual Phase 1.5V/30A Step-Down Converter 5V

VIN 4.5V TO 28V

47.5k VCC DRVCC ION ×3

TRACK TG1 HAT2168H

Efficiency and Power Loss

FCB BOOST1

VIN = 12V

100k SW1 0.1µF

PGOOD SENSE1+

EFFICIENCY

RUN/SS BG1 HAT2165H

3.32k EXTLPF SENSE1– INTLPF PGND1

100n F ITH LTC3709

20k VIN

SGND TG2 HAT2168H

POWER LOSS

10k BOOST2

1.22µH VOUT

VFB SW2 1.5V

DIFFOUT SENSE2+ 30A

BG2 HAT2165H 0.01 0.1

VOS 330µF LOAD CURRENT (A)

SENSE2–

2.5V 3709 TA01b

PGND2 ×4

3709 TA01a

3709fa