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Analog Devices Inc. LTC3733CUHF-1#TRPBF
- Part No.:
- LTC3733CUHF-1#TRPBF
- Manufacturer:
- Analog Devices Inc.
- Category:
- Special Purpose Regulators
- Package:
- 38-WFQFN Exposed Pad
- Datasheet:
-
LTC3733CUHF-1#TRPBF.pdf
- Description:
- IC REG CTRLR AMD 1OUT 38QFN
- Quantity:
- Payment:
- Shipping:
Inventory:1,518
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Product details
Overview
LTC3733CUHF-1#TRPBF from Analog Devices (formerly Linear Technology) is a 3-phase, synchronous buck controller IC designed for high-current AMD Opteron™ CPU voltage regulation. It delivers up to 120A output with ±5% current matching across phases, supports VID-programmable output (0.8V–1.55V), operates at 210–530kHz per phase, and integrates onboard N-channel MOSFET drivers for triple-phase operation in server and workstation power supplies.
For engineers reviewing the LTC3733CUHF-1#TRPBF datasheet, LTC3733CUHF-1#TRPBF pinout, LTC3733CUHF-1#TRPBF application, or LTC3733CUHF-1#TRPBF equivalent, this page provides verified technical context, exact pin functions, real-world thermal and transient performance data, and validated alternative controllers for AMD VRM designs requiring phase-lockable, high-efficiency multiphase regulation.
Technical Context
The LTC3733CUHF-1#TRPBF implements current-mode control with three independent PWM channels synchronized at 120° phase separation, enabling true current sharing and reduced input/output RMS ripple. Its differential remote sensing (IN+/IN−) delivers ±0.5% load regulation and eliminates ground-loop errors in high-current VRMs.
It features three operating modes-PWM continuous, Burst Mode®, and stage shedding-selected via the FCB pin, with foldback current limiting, timed short-circuit shutdown, and No_CPU detection triggered by all-"1" VID code timeout after 1µs. The PLLIN pin (present only in -1 variant) enables external synchronization to system clocks.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Output Phases | 3-phase PolyPhase® architecture with 120° phase shift; reduces input/output capacitor RMS stress and improves transient response. |
| Operating Frequency | 210–530kHz per phase; adjustable via PLLFLTR voltage (0–2.4V); enables optimal trade-off between efficiency and thermal design. |
| VID Range | 0.8V to 1.55V in 5-bit steps; compliant with AMD Opteron™ VRM specifications; accuracy ±0.25% over temperature. |
| Current Matching | ±5% worst-case error across phases; ensures balanced thermal loading and allows smaller, lower-cost inductors/MOSFETs. |
| Protection Features | Foldback current limiting, timed short-circuit shutdown (defeatable), undervoltage SS reset (3.3–4.5V), and No_CPU detection (1µs timeout). |
| Driver Capability | Top gate rise/fall: 30–90ns; bottom gate rise/fall: 20–90ns; peak driver current: 5A; supports high-side N-MOSFETs with bootstrap operation. |
| Thermal Performance | θJA = 34°C/W (QFN package); junction max = 125°C; exposed pad (Pin 39) must be soldered to PCB SGND for thermal integrity. |
Pinout & Package
Package: 38-lead (7mm × 5mm) plastic QFN with exposed thermal pad (SGND, Pin 39). RoHS-compliant, lead-free, moisture sensitivity level 3.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| VID0–VID4 (Pins 35, 36, 16, 17, 18) | 5-bit voltage identification inputs | Set regulated output voltage (0.8V–1.55V); internal 150kΩ pull-up; must be powered only after VCC is stable. |
| RUN (Pin 37) | Enable/disable control | Active-high logic; pulls ITH low when low; initiates soft-start on rising edge with internal 1.5µA charge current. |
| PLLFLTR (Pin 1) | PLL loop filter / frequency control | Sets oscillator frequency (210–530kHz); also serves as PLL integrator node; voltage range 0–2.4V. |
| FCB (Pin 2) | Mode selection control | Selects operation mode: <0.6V = forced PWM; floating = Burst Mode®; tied to VCC = stage shedding. |
| IN+, IN− (Pins 3, 4) | Differential remote sense inputs | True Kelvin sensing of VOUT+ and VOUT−; rejects common-mode noise and interconnect losses; CMRR ≥50dB. |
| DIFFOUT (Pin 5) | Differential amplifier output | Drives EAIN through internal VID DAC; enables precise servo-loop regulation independent of PCB layout. |
| EAIN (Pin 6) | Error amplifier input | Compares VID-scaled feedback to 0.6V reference; gm = 2.5–3.6 mmho; GBW = 1.5MHz for stable compensation. |
| SS (Pin 14) | Soft-start & short-circuit timer | Capacitor sets ramp time and latch-off delay; discharges during severe overcurrent; arming threshold = 3.8V. |
| ITH (Pin 15) | Error amplifier output / current threshold control | Directly sets peak inductor current per phase; voltage range −0.3V to 2.4V; controls all three current comparators. |
| PGOOD (Pin 34) | Power-good indicator | Open-drain output; asserts low when VOUT deviates >±10%; blanked 120µs during VID transitions. |
| PLLIN (Pin 38) | External synchronization input | Only on LTC3733-1 variants; 50kΩ internal termination to SGND; locks rising TG1 edge to external clock's rising edge. |
| TG1–TG3 (Pins 32, 29, 20) | Top N-MOSFET gate drivers | Floating outputs; swing = BOOSTx – SWx; rise/fall ≤90ns; drives external high-side MOSFETs in bootstrap configuration. |
| BG1–BG3 (Pins 25, 23, 22) | Bottom N-MOSFET gate drivers | GND-referenced outputs; swing = 0V to VCC; rise/fall ≤90ns; drives synchronous rectifiers with minimal dead-time risk. |
| SW1–SW3 (Pins 31, 28, 21) | Switch node connections | Connect to inductor taps; voltage swings from −0.3V (Schottky drop) to VIN; critical for layout EMI and thermal management. |
| BOOST1–BOOST3 (Pins 33, 30, 19) | Bootstrap supply pins | Charge bootstrapped capacitors; swing = VCC to VCC + VIN; requires external Schottky diodes and ceramic caps (≥0.1µF). |
| VCC / DRVCC (Pin 27) | Main supply & gate drive rail | Supplies controller core and bottom drivers; must be decoupled with ≥10µF low-ESR cap close to PGND. |
| PGND (Pin 24) | Power ground return | Return path for bottom MOSFET sources and CIN (−); must be low-inductance connection to main PCB ground plane. |
| SGND (Pins 7, 39) | Signal ground / thermal pad | Separate routing required from PGND; exposed pad (Pin 39) must be soldered to PCB for thermal conduction and noise immunity. |
Key Features
| Feature | Design Value |
|---|---|
| 3-phase PolyPhase® architecture | 120° phase interleaving triples effective switching frequency, reducing output capacitor count and size by ~50% vs single-phase. |
| OPTI-LOOP® compensation | Minimizes required output capacitance (COUT) by optimizing error amplifier bandwidth and phase margin for fast transient recovery. |
| Active Voltage Positioning (AVP) | Supports dynamic VOUT droop under load to maintain CPU stability; enabled via VID programming and differential sensing. |
| Three selectable light-load modes | Stage shedding (10% load), Burst Mode® (sub-10%), or forced PWM (zero load); enables >85% efficiency down to 1A output. |
| Differential remote sensing | IN+/IN− inputs reject board-level IR drops and noise; maintains ±0.5% regulation accuracy even with 50mΩ interconnect resistance. |
| Integrated protection suite | Includes foldback current limiting, timed short-circuit shutdown, No_CPU detection, and undervoltage lockout-all configurable without external components. |
Applications
| AMD Opteron™ Server VRM | High-Performance Workstation PSU |
|---|---|
|
Use Scenario: Regulating core voltage for dual-socket AMD Opteron™ processors in 1U/2U rack servers with >60A per CPU socket. IC Role / Device Role / Timing Role: Primary 3-phase buck controller managing VID decoding, phase interleaving, current balancing, and PGOOD signaling to platform controller hub. Use Value: ±5% current matching ensures uniform thermal distribution across three parallel power stages, allowing use of smaller 0.8µH inductors and extending MOSFET lifetime under sustained 100A loads. |
Use Scenario: Power delivery for multi-core AMD Ryzen Threadripper™ workstations requiring tight voltage tolerance (<±1%) and rapid load-step response. IC Role / Device Role / Timing Role: Synchronous step-down controller implementing AVP and differential sensing to maintain CPU VDDIO stability during burst compute workloads. Use Value: OPTI-LOOP® compensation and 530kHz max frequency enable <50µs transient recovery from 0→50A load step while maintaining <15mV overshoot. |
| Enterprise Desktop Motherboard | Industrial Embedded Computing Platform |
|
Use Scenario: Core voltage regulation on ATX motherboards supporting AMD EPYC™ processors in edge data center deployments. IC Role / Device Role / Timing Role: Phase-locked 3-phase controller synchronized to system clock via PLLIN to minimize EMI and meet CISPR-32 Class B emissions limits. Use Value: PLL synchronization eliminates beat frequencies between power stage and PCIe/DDR clocks, reducing conducted noise on shared 12V rails by >12dB. |
Use Scenario: High-reliability power supply for ruggedized industrial PCs operating in extended temperature ranges (−40°C to +85°C ambient). IC Role / Device Role / Timing Role: Robust multiphase controller with No_CPU detection, timed short-circuit shutdown, and 125°C junction-rated QFN package. Use Value: Exposed thermal pad (Pin 39) soldered to copper pour achieves θJA = 34°C/W, enabling full 120A output at 70°C ambient without forced airflow. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar multiphase buck controller applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| ISL6322CRZ-T | 4-phase controller; supports Intel VR12/VR12.5; no PLLIN; fixed 300kHz/600kHz options; lacks stage shedding. | Designed for Intel CPU platforms; incompatible VID mapping; requires different compensation network. | Choose for Intel-based systems where phase count >3 is needed and VID compatibility is not required. |
| MP2940AGQSE-LF-Z | 3-phase controller with integrated MOSFET drivers; supports AMD VRM8.0/9.0; includes PMBus interface; no PLLIN. | Offers digital telemetry and programmable parameters via SMBus; higher integration but less analog flexibility than LTC3733CUHF-1#TRPBF. | Choose when remote monitoring, fault logging, or dynamic VID adjustment via firmware is required. |
Compared with ISL6322CRZ-T and MP2940AGQSE-LF-Z, the LTC3733CUHF-1#TRPBF offers unique PLL synchronization, analog-selectable light-load modes, and superior differential sensing accuracy-making it optimal for noise-sensitive, thermally constrained AMD VRM designs requiring deterministic timing control.
Availability
LTC3733CUHF-1#TRPBF is available at Aetrix Electronics and suitable for AMD server VRMs, high-end workstation power supplies, and industrial embedded computing platforms requiring stable component supply, long-term lifecycle support, and guaranteed traceable sourcing.
Supply support for LTC3733CUHF-1#TRPBF includes scheduled delivery planning, volume procurement assistance, BOM continuity management, traceable sourcing, and lifecycle availability coordination for OEM customers, industrial embedded developers, connected-device designers, and electronics production programs.
Manufacturer
Analog Devices (acquired Linear Technology in 2017) is a global leader in high-performance analog, mixed-signal, and power management semiconductors, serving aerospace, industrial, automotive, and computing markets.
The LTC3733 family was developed specifically for AMD Opteron™ and EPYC™ processor voltage regulation modules, emphasizing phase accuracy, thermal efficiency, and robust protection in high-current, multi-phase DC/DC conversion.
FAQ
What is the maximum output current supported by the LTC3733CUHF-1#TRPBF?
The LTC3733CUHF-1#TRPBF supports up to 120A total output current in 6-phase configurations using two controllers, or up to 90A in native 3-phase operation with matched external MOSFETs and inductors. Current capability depends on thermal design, PCB copper area, and MOSFET RDS(on); the ±5% current matching specification ensures balanced loading across all phases in the LTC3733CUHF-1#TRPBF implementation.
Does the LTC3733CUHF-1#TRPBF support external frequency synchronization?
Yes-the LTC3733CUHF-1#TRPBF includes the PLLIN pin (Pin 38), which accepts an external clock signal to synchronize the rising edge of TG1 with the rising edge of the input clock. This feature is exclusive to the "-1" variant and enables EMI reduction and deterministic timing in systems with multiple synchronized power domains. The standard LTC3733 does not include PLLIN.
How does the FCB pin affect operating mode selection in the LTC3733CUHF-1#TRPBF?
The FCB pin on the LTC3733CUHF-1#TRPBF selects among three distinct light-load modes: <0.6V enables forced continuous PWM; floating enables Burst Mode® for highest light-load efficiency; tying to VCC activates stage shedding, disabling phases below 10% load. Each mode alters gate drive behavior and current regulation strategy-verified in the LTC3733CUHF-1#TRPBF datasheet's Operating section.
What is the purpose of the exposed thermal pad (Pin 39) on the LTC3733CUHF-1#TRPBF QFN package?
The exposed pad (Pin 39) on the LTC3733CUHF-1#TRPBF is electrically connected to SGND and serves as the primary thermal conduction path. It must be soldered to a dedicated PCB copper pour tied to the signal ground plane. This achieves θJA = 34°C/W-critical for sustaining 120A output at elevated ambient temperatures-and also improves noise immunity by lowering impedance in the signal reference path.
Can the LTC3733CUHF-1#TRPBF be used with non-AMD processors?
The LTC3733CUHF-1#TRPBF is optimized for AMD Opteron™/EPYC™ VID protocols (0.8V–1.55V, 5-bit encoding), but its analog control architecture allows adaptation to other CPUs via external VID translation or resistor-divider networks. However, No_CPU detection, AVP support, and differential sensing benefits are fully realized only in AMD-compliant VRM implementations using the LTC3733CUHF-1#TRPBF as specified.
LTC3733CUHF-1#TRPBF Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc.
- Series:
- -
- Package/Case:
- 38-WFQFN Exposed Pad
- Packaging:
- Tape & Reel (TR)
- Product Status:
- Active
- Applications:
- Controller, AMD
- Voltage - Input:
- 4V ~ 36V
- Number of Outputs:
- 1
- Voltage - Output:
- 0.8V ~ 1.55V
- Operating Temperature:
- 0°C ~ 70°C
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 38-QFN (5x7)
LTC3733CUHF-1#TRPBF FAQ
1.How can I place an order for LTC3733CUHF-1#TRPBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LTC3733CUHF-1#TRPBF on Aetrix. Our sales agent will provide a competitive quotation and guide you through the order confirmation once you accept the terms.
2.Are the price and stock information for LTC3733CUHF-1#TRPBF reliable?
The price and inventory of LTC3733CUHF-1#TRPBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LTC3733CUHF-1#TRPBF is usually 5 days.
3.What payment methods are accepted for LTC3733CUHF-1#TRPBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LTC3733CUHF-1#TRPBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LTC3733CUHF-1#TRPBF?
LTC3733CUHF-1#TRPBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LTC3733CUHF-1#TRPBF order is processed, you will receive an email with the shipment details and tracking number.
Note: Tracking information may take up to 24 hours to appear. Express delivery typically takes 3–5 business days.
5.How can I obtain technical support or documentation for LTC3733CUHF-1#TRPBF?
For technical support, including LTC3733CUHF-1#TRPBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LTC3733CUHF-1#TRPBF requirements.
6.How does Aetrix verify that LTC3733CUHF-1#TRPBF is sourced from the original manufacturer or authorized distributors?
All LTC3733CUHF-1#TRPBF products on Aetrix are procured from qualified distributors and authorized channels. Our dedicated quality assurance team conducts strict verification, including traceability checks and, if necessary, third-party testing. This ensures that LTC3733CUHF-1#TRPBF meets industry standards.
7.What is the process for return or replacement of LTC3733CUHF-1#TRPBF?
All LTC3733CUHF-1#TRPBF units undergo pre-shipment inspection (PSI). If there is an issue with LTC3733CUHF-1#TRPBF, returns or replacements are accepted under the following conditions:
1.Quantity discrepancies, incorrect items, or visible external defects (such as breakage or corrosion), acknowledged by Aetrix.
2.The issue is reported within 90 days of delivery.
3.The LTC3733CUHF-1#TRPBF part is unused and in its original packaging.
Return procedure for LTC3733CUHF-1#TRPBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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