LINEAR TECHNOLOGY LTC3733 LTC3733-1 Data Sheet Manual
Summary
This advanced 3-Phase Synchronous Buck Controller is engineered for high-performance, current-sharing power delivery in demanding applications like servers, workstations, and high-end computing CPUs. The manual details a robust architecture featuring phase separation up to 530kHz and accurate Voltage ID (VID) support ranging from 0.8V to 1.55V. It provides comprehensive protection, including OPTI-LOOP compensation and short-circuit shutdown, ensuring maximum efficiency and stability for modern processors requiring massive power output.
Page 1 Text Content
LTC3733/LTC3733-1 3-Phase, Buck
Controllers for AMD CPUs
FEATURES DESCRIPTIO 3-Phase Controller with Onboard MOSFET Drivers The LTC®3733 family are Poly Phase® synchronous step- Current Mode Control Ensures Current Sharing down switching regulator controllers that drive all Differential Amplifier Accurately Senses VOUT N-channel external power MOSFET stages in a phase-
±5% Output Current Matching Optimizes Thermal lockable, fixed frequency architecture. The 3-phase con- Performance and Size of Inductors and MOSFETs troller drives its output stages with 120° phase separation Reduced Input and Output Capacitance at frequencies of up to 530k Hz per phase to minimize the Supports Active Voltage Positioning RMS current dissipated by the ESR of both the input and VID Programmable Output Voltage from 0.8V to 1.55V output filter capacitors. The 3-phase technique effectively (AMD Opteron TM CPU) triples the fundamental frequency, improving transient 6-Phase, 90A to 120A Operation response while operating each phase at an optimal fre- Output Power Good Indicator with Adaptive Blanking quency for efficiency and ease of thermal design. Light 210k Hz to 530k Hz Per Phase, PLL, Fixed Frequency load efficiency is optimized by using a choice of output Synchronizable (LTC3733-1) stage shedding or Burst Mode technology.
PWM, Stage Shedding or Burst Mode® Operation
A differential amplifier provides true remote sensing of both
OPTI-LOOP® Compensation Minimizes COUT
the high and low sides of the output voltage at load points.
Adjustable Soft-Start Current Ramping
Soft-start and a defeatable, timed short-circuit shutdown
Short-Circuit Shutdown Timer with Defeat Option
protect the MOSFETs and the load. A foldback current
No_CPU Detection
circuit also provides protection for the external MOSFETs
36-Lead 0.209" SSOP and 38-Lead (5mm × 7mm) QFN
under short-circuit or overload conditions. An all-“1” VID APPLICATIO detector turns off the regulator after 1µs timeout. , LTC and LT are registered trademarks of Linear Technology Corporation. High Performance Notebook Computers Burst Mode, OPTI-LOOP and Poly Phase are registered trademarks of Linear Technology Corporation. AMD Opteron is a trademark of Advanced Micro Devices, Inc.
Servers, Desktop Computers and Workstations
TYPICAL APPLICATIO
VIN 5V TG1VCC 5V TO 28V 22µF
LTC3733-1 0.002ΩL1 0.8µH
10µF SW1 35V ×2
BOOST1 D1
BOOST2 BOOST3
0.1µF SENSE1+ SENSE1–
SW3 SW2 SW1 VIN
POWER GOOD INDICATOR PGOOD TG2
0.002ΩL2 0.8µH VOUT
PLLINOPTIONAL SYN IN
SW2 0.8V TO 1.55V
PLLFLTR 65A
BG2 D2 5 VID BITS PGNDVID0-VID4
ON/OFF RUN SENSE2+
680p F SENSE2–
ITH TG3
5k SS
SGND BG3 D3
100p F SENSE3+
SENSE3–IN–
IN+ 4V
Figure 1. High Current Triple Phase Step-Down Converter
Page Summary Contents For LINEAR TECHNOLOGY LTC3733 LTC3733-1 Data Sheet Manual
Manual Details
| Brand | Linear |
|---|---|
| Pages | 32 |
| File Size | 285.96 KB |
| Published | June 16, 2026 |
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Frequently Asked Questions
What range of voltage does the programmable optimal output support?
The programmable output voltage (VID) can be set from 0.8V to 1.55V.
How does the three-phase technique improve performance?
It improves the transient response and allows each phase to operate at an optimal frequency, up to 530kHz per phase.
What safety protections are built into this controller?
Protection features include Short-Circuit Shutdown after a timed delay option, foldback current, and a detection circuit for external MOSFETs.
What is the required operating ambient temperature range?
The unit supports an operating ambient temperature range of 0°C to 70°C.