Datasheet LTC3729L-6 (Analog Devices)

LTC3729L-6 PolyPhase, Synchronous Step-Down Switching Regulator
U FEATURES DESCRIPTIO
■
Reduces Required Input Capacitance and Power
The LTC®3729L-6 is a PolyPhaseTM synchronous step-
Supply Induced Noise
down current mode switching regulator controller with a ■
True Remote Sensing Differential Amplifier
0.6V reference that drives N-channel external power ■
0.6V,
±
1% Voltage Reference Accuracy
MOSFET stages in a phase-lockable fixed frequency archi- ■ PolyPhase Controller Operates from Two to Twelve tecture. The PolyPhase controller drives its two output Phases stages out of phase at frequencies up to 550kHz to ■ Current Mode Control Ensures Current Sharing minimize the RMS ripple currents in both input and output ■ Phase-Lockable Fixed Frequency: 250kHz to 550kHz capacitors. The output clock signal allows expansion for ■ OPTI-LOOP® Compensation Reduces C up to 12 evenly phased controllers for systems requiring OUT ■ Power Good Output Voltage Monitor 15A to 200A of output current. This PolyPhase technique ■ Wide V effectively multiplies the fundamental frequency by the IN Range: 4V to 30V Operation ■ Very Low Dropout Operation: 99% Duty Cycle number of channels used, improving transient response ■ Adjustable Soft-Start Current Ramping while operating each channel at an optimum frequency for ■ Internal Current Foldback Plus Shutdown Timer efficiency. Thermal design is also simplified. ■ Overvoltage Soft-Latch Eliminates Nuisance Trips An internal differential amplifier provides true remote ■ Micropower Shutdown sensing of the regulated supply’s positive and negative ■ 32-Lead 5mm × 5mm Plastic QFN Package output terminals as required for high current applications.
U APPLICATIO S
A RUN/SS pin provides both soft-start and optional timed, short-circuit shutdown. Current foldback limits MOSFET ■ Desktop Computers dissipation during short-circuit conditions when the ■ Internet Servers overcurrent latchoff is disabled. OPTI-LOOP compensa- ■ Large Memory Arrays tion allows the transient response to be optimized over a ■ DC Power Distribution Systems wide range of output capacitance and ESR values. The , LTC and LT are registered trademarks of Linear Technology Corporation. LTC3729L-6 includes a power good output pin that OPTI-LOOP is a registered trademark of Linear Technology Corporation. indicates when the output voltage is inside the PolyPhase is a trademark of Linear Technology Corporation. ±10% tolerance window.
U TYPICAL APPLICATIO
10Ω VIN 0.1µF 10µF ×6 5V TO 15V 35V S V LTC3729L-6 TG1 M1 IN S CERAMIC BOOST1 0.002Ω 0.1µF 0.47µF SW1 L1 RUN/SS S M2 BG1 1µH ×2 D1 PGOOD PGND 3300pF SENSE1+ ITH SENSE1– 1.5k CLKOUT TG2 M3 S S SGND BOOST2 0.002Ω V 0.47µF OUT SW2 10k L2 0.7V/40A S S M4 V BG2 1µH DIFFOUT ×2 D2 S EAIN INTVCC S 10µF CER + C V – SENSE2+ OUT OS 60.4k X5R 270µF ×4 V + SENSE2– OS 2V C L1, L2: CEPH149-IROMC-H OUT: T510E108K004AS M1, M3: Si7840DP 3729L-6 TA01 D1, D2: SBM540 M2, M4: Si7440DP
Figure 1. High Current Dual Phase Step-Down Converter
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