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Analog Devices Inc. LTC7851IUHH#TRPBF
- Part No.:
- LTC7851IUHH#TRPBF
- Manufacturer:
- Analog Devices Inc.
- Category:
- DC DC Switching Controllers
- Package:
- 58-WFQFN Exposed Pad
- Datasheet:
-
LTC7851IUHH#TRPBF.pdf
- Description:
- IC REG CTRLR BUCK 58QFN
- Quantity:
- Payment:
- Shipping:
Inventory:2,335
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Product details
Overview
LTC7851IUHH#TRPBF from Analog Devices is a quad-output, multiphase synchronous step-down voltage mode DC/DC controller supporting up to 4 independent or paralleled phases, with ±0.75% 0.6V reference accuracy, 250kHz–2.25MHz programmable switching frequency, and lossless DCR or precision resistor current sensing. It delivers precise current sharing across channels and is optimized for high-current FPGA/DSP supplies using DrMOS or power blocks.
For engineers reviewing the LTC7851IUHH#TRPBF datasheet, LTC7851IUHH#TRPBF pinout, LTC7851IUHH#TRPBF application, or LTC7851IUHH#TRPBF equivalent, key selection criteria include its quad-phase voltage-mode architecture, internal current-sharing loop, 58-lead QFN package with exposed thermal pad, VCC range of 3V–5.5V, and compatibility with DrMOS devices requiring low-gain current sense amplification.
Technical Context
The LTC7851IUHH#TRPBF implements a constant-frequency voltage-mode control architecture with four independent error amplifiers (COMP1–COMP4), each driving a PWM output with line feedforward via VINSNS. Its internal current-sharing loop uses IAVG pins to average master-phase inductor current and dynamically adjust slave-phase duty cycles for tight inter-phase current balance.
It supports flexible configuration: single-chip quad-output operation, multiphase extension via daisy-chained CLKOUT/CLKIN, and master-slave topology with VSNSOUT and IAVG bus connections. The device features phase-lockable oscillator (250kHz–2.25MHz), ±1mV current-sense offset (LTC7851 variant), and dedicated tracking/soft-start pins per channel for coordinated startup sequencing.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| VOUT Range | 0.6V to VCC – 0.5V - Enables regulation down to sub-1V rails required by modern FPGAs and ASICs. |
| Switching Frequency | 250kHz to 2.25MHz - Adjustable via FREQ pin resistor or external CLKIN; higher frequencies allow smaller magnetics and faster transient response. |
| Reference Accuracy | ±0.75% at 0.6V - Ensures tight output voltage tolerance across temperature and load, critical for core rail stability. |
| Current Sense Gain | 20 V/V - Fixed gain for LTC7851 (vs. 4 V/V for LTC7851-1); matches standard external sense resistors or DCR networks. |
| VCC Supply Range | 3V to 5.5V - Compatible with common 3.3V or 5V bias rails; supports operation from intermediate supply domains. |
| Operating Temp | –40°C to +125°C - Industrial-grade junction temperature rating ensures reliability in demanding embedded and telecom environments. |
| Package | 58-lead 5mm × 9mm QFN with exposed SGND pad - Provides low thermal resistance (θJC = 15.5°C/W) for high-power density designs. |
Pinout & Package
Package: 58-lead plastic QFN (5mm × 9mm, 0.4mm pitch), exposed thermal pad (Pin 59) connected to SGND. Requires soldering of exposed pad to PCB ground plane for rated thermal performance (θJA = 49°C/W).
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| COMP1–COMP4 (Pins 1,9,13,20) | Error amplifier output | Drives PWM comparator; low-impedance op-amp output; must not be directly paralleled unless FB tied to VCC to three-state slave outputs. |
| VSNSP1–VSNSP4 (Pins 2,8,14,19) | Differential sense non-inverting input | Connects to midpoint of output voltage divider for remote sensing; rejects ground noise between local and load ground. |
| VSNSN1–VSNSN4 (Pins 3,7,15,18) | Differential sense inverting input | Connects to load ground; enables accurate differential measurement despite PCB ground bounce or IR drop. |
| IAVG1–IAVG4 (Pins 47,42,35,30) | Average current monitor | Stores master-phase average current as voltage on external capacitor; shared bus enables real-time current balancing across phases. |
| ILIM1–ILIM4 (Pins 48,41,36,29) | Overcurrent threshold set | Sources 20µA in master mode; voltage developed across external resistor sets per-channel OC trip point. |
| RUN1–RUN4 (Pins 53,51,27,23) | Channel enable input | Logic-high (>2.25V) enables channel; internal 1.5µA pull-up allows simple resistor-enable; <2V forces shutdown. |
| PWM1–PWM4 (Pins 52,50,26,24) | Top gate drive output | Three-state compatible; drives external gate driver or DrMOS top-FET input; minimum on/off times prevent shoot-through. |
| PGOOD1–PGOOD4 (Pins 49,38,28,25) | Open-drain power-good indicator | Pulls low when output deviates >±10% from target after 30µs mask timer; supports system-level fault monitoring and sequencing. |
Key Features
| Feature | Design Value |
|---|---|
| Quad differential output voltage sense amplifiers | Enables true remote sensing across all four outputs, eliminating errors from PCB trace resistance and ground shifts. |
| Voltage mode control with accurate current sharing | Internal current-sharing loop maintains ≤3% inter-phase current mismatch under dynamic load steps, reducing thermal stress on individual power stages. |
| Phase-lockable fixed-frequency oscillator | Supports synchronization to external clock (250kHz–2.25MHz) or resistor-programmed frequency, enabling EMI spread-spectrum and multi-controller coherence. |
| Lossless current sensing via DCR or precision resistor | Eliminates power loss and board space associated with shunt resistors; supports both discrete MOSFET and integrated DrMOS solutions. |
| Output voltage tracking with soft-start | TRACK/SS pins allow coordinated ramp-up of multiple rails (e.g., core and I/O) using resistor dividers, preventing latch-up during power-on. |
Applications
| FPGA Core Power Supply | DSP/ASIC Multi-Rail System |
|---|---|
Use Scenario: Powering Xilinx UltraScale+ or Intel Stratix 10 FPGA core rails requiring 0.8V/100A with tight transient regulation and phase interleaving. IC Role / Device Role / Timing Role: Quad-phase controller managing four parallel DrMOS stages, coordinating PWM timing with 90° phase offsets to reduce input/output ripple. Use Value: Achieves <50mV output deviation under 50A/µs load step while maintaining <±1% current balance across phases, extending power stage lifetime. | Use Scenario: Generating synchronized 1.2V core, 1.8V I/O, and 3.3V auxiliary rails for TI C66x DSP-based radar processing units. IC Role / Device Role / Timing Role: Single-chip quad-output controller with independent TRACK/SS pins enabling coincident startup and independent voltage programming per rail. Use Value: Eliminates need for external sequencing ICs; reduces BOM count by 3+ components while ensuring monotonic ramp-up per JEDEC JESD8-12 specification. |
| High-Density Telecom Server PSU | Datacenter GPU Accelerator Board |
Use Scenario: 48V-to-12V intermediate bus conversion feeding multiple point-of-load regulators in compact 1RU server chassis. IC Role / Device Role / Timing Role: Master controller in daisy-chained multiphase stack (2× LTC7851), driving 8 total phases via CLKOUT→CLKIN interconnect for 200A+ aggregate output. Use Value: Reduces RMS input current ripple by 70% vs. single-phase design, lowering bulk capacitor size and EMI filter requirements. | Use Scenario: Providing 0.95V/300A core voltage to NVIDIA A100 GPU with strict ±15mV regulation window and <10µs transient recovery. IC Role / Device Role / Timing Role: Four-phase controller operating at 1MHz with 0.25µH inductors and FDMF5820DC DrMOS, leveraging VINSNS feedforward for line-step rejection. Use Value: Delivers 92% peak efficiency at 200A and recovers within 8µs from 150A load step-meeting PCIe Gen5 VR13.1 compliance thresholds. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar quad-output multiphase controller applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| ISL95815IRZ-T7A | Triple-output controller (not quad); uses different current-sense architecture (no DCR support); max fSW = 1.5MHz | Targeted at mobile CPU VRs; lacks independent TRACK/SS per channel and PGOOD per phase | Select only if triple-rail requirement suffices and DrMOS compatibility with DCR sensing is not needed. |
| MP2960AGQSE-Z | Quad-output but fixed 600kHz/1MHz dual-frequency option; no external frequency resistor; lower VOUT min = 0.5V | Designed for client notebook VRMs; lacks CLKIN/CLKOUT daisy-chain and has no VINSNS feedforward | Choose for cost-sensitive consumer applications where EMI control via variable frequency and line feedforward are not required. |
Compared with ISL95815IRZ-T7A and MP2960AGQSE-Z, the LTC7851IUHH#TRPBF provides full quad-channel independence, programmable frequency over widest range (250kHz–2.25MHz), and superior transient performance via VINSNS feedforward and high-bandwidth error amplifiers-making it optimal for high-reliability industrial and datacenter power systems.
Availability
LTC7851IUHH#TRPBF is available at Aetrix Electronics and suitable for high-current FPGA power supplies, telecom server intermediate bus converters, and AI accelerator board designs requiring stable component supply and long-term production continuity.
Supply support for LTC7851IUHH#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, Inc. is a global leader in high-performance analog, mixed-signal, and digital signal processing semiconductors, serving industrial, automotive, communications, and aerospace markets.
The LTC7851IUHH#TRPBF belongs to Analog Devices' Power by Linear™ controller family, engineered specifically for high-efficiency, high-density multiphase DC/DC conversion in computing, networking, and AI infrastructure applications.
FAQ
What is the difference between LTC7851IUHH#TRPBF and LTC7851IUHH-1#TRPBF?
The LTC7851IUHH#TRPBF is the standard-gain version with 20 V/V current sense amplifier gain, optimized for external sense resistors or DCR networks. The LTC7851IUHH-1#TRPBF has reduced 4 V/V gain, tailored for DrMOS devices with internal current sense outputs that deliver higher signal levels. Both share identical pinout, package, and feature set except for this gain difference.
Does LTC7851IUHH#TRPBF support daisy-chaining with other LTC7851 controllers?
Yes, LTC7851IUHH#TRPBF supports daisy-chaining via CLKOUT and CLKIN pins. When multiple LTC7851IUHH#TRPBF devices are connected (CLKOUT of master → CLKIN of slave), they synchronize switching frequency and phase alignment, enabling seamless expansion to 8+ phases without external clock generators.
Can LTC7851IUHH#TRPBF operate with only two active phases while keeping the other two disabled?
Yes, LTC7851IUHH#TRPBF supports partial-phase operation. By pulling RUN3 and RUN4 low (≤2V), Channels 3 and 4 are fully disabled, while Channels 1 and 2 remain active with independent feedback and current sensing. This allows flexible configuration from 1–4 phases per controller without hardware modification.
What is the purpose of the VSNSP/VSNSN pins on LTC7851IUHH#TRPBF?
The VSNSP and VSNSN pins on LTC7851IUHH#TRPBF form a differential amplifier input pair for remote output voltage sensing. VSNSP connects to the center tap of the output voltage divider, and VSNSN connects to the load ground. This configuration rejects PCB ground noise and ensures accurate regulation at the point of load, independent of trace IR drop.
How does the IAVG pin function in multiphase current sharing on LTC7851IUHH#TRPBF?
The IAVG pin on LTC7851IUHH#TRPBF outputs a voltage proportional to the instantaneous average inductor current of its master channel. In multiphase setups, all IAVG pins are tied together; slave channels compare their sensed current against this master reference and adjust duty cycle via internal integrators, achieving ≤3% current mismatch across phases under steady-state and transient conditions.
LTC7851IUHH#TRPBF Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc.
- Series:
- -
- Package/Case:
- 58-WFQFN Exposed Pad
- Packaging:
- Tape & Reel (TR)
- Product Status:
- Active
- Output Type:
- PWM Signal
- Function:
- Step-Down
- Output Configuration:
- Positive
- Topology:
- Buck
- Number of Outputs:
- 4
- Output Phases:
- 1
- Voltage - Supply (Vcc/Vdd):
- 3V ~ 5.5V
- Frequency - Switching:
- 250kHz ~ 3MHz
- Duty Cycle (Max):
- 91.5%
- Synchronous Rectifier:
- No
- Clock Sync:
- No
- Serial Interfaces:
- -
- Control Features:
- Current Limit, Enable, Frequency Control, Power Good, Soft Start, Tracking
- Operating Temperature:
- -40°C ~ 125°C (TJ)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 58-QFN (5x9)
LTC7851IUHH#TRPBF FAQ
1.How can I place an order for LTC7851IUHH#TRPBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LTC7851IUHH#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 LTC7851IUHH#TRPBF reliable?
The price and inventory of LTC7851IUHH#TRPBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LTC7851IUHH#TRPBF is usually 5 days.
3.What payment methods are accepted for LTC7851IUHH#TRPBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LTC7851IUHH#TRPBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LTC7851IUHH#TRPBF?
LTC7851IUHH#TRPBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LTC7851IUHH#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 LTC7851IUHH#TRPBF?
For technical support, including LTC7851IUHH#TRPBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LTC7851IUHH#TRPBF requirements.
6.How does Aetrix verify that LTC7851IUHH#TRPBF is sourced from the original manufacturer or authorized distributors?
All LTC7851IUHH#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 LTC7851IUHH#TRPBF meets industry standards.
7.What is the process for return or replacement of LTC7851IUHH#TRPBF?
All LTC7851IUHH#TRPBF units undergo pre-shipment inspection (PSI). If there is an issue with LTC7851IUHH#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 LTC7851IUHH#TRPBF part is unused and in its original packaging.
Return procedure for LTC7851IUHH#TRPBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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