Analog Devices Inc. LTC3874IUFD#TRPBF

Overview

LTC3874IUFD#TRPBF from Analog Devices is a dual-phase PolyPhase® synchronous step-down slave controller designed for high-current, multi-phase DC/DC conversion. It operates with companion master controllers (e.g., LTC3884, LTC3875), supports 250kHz–1MHz switching, enables sub-milliohm DCR current sensing (down to 0.2mΩ), and delivers precise phase-to-phase current sharing in telecom and datacom power rails up to 120A.

For engineers reviewing the LTC3874IUFD#TRPBF datasheet, LTC3874IUFD#TRPBF pinout, LTC3874IUFD#TRPBF application, or LTC3874IUFD#TRPBF equivalent, key selection criteria include its dual-channel peak-current-mode architecture, programmable CCM/DCM operation, PHASMD-controlled phase alignment, and compatibility with master ICs for scalable phase extension beyond 4 phases.

Technical Context

The LTC3874IUFD#TRPBF implements a proprietary current mode control loop where ITH voltage from the master controller directly sets per-channel peak inductor current. Its sub-milliohm DCR sensing architecture improves signal-to-noise ratio by 14dB, enabling accurate current measurement with 0.32mΩ inductors while reducing switching jitter.

It features dual N-channel MOSFET gate drivers (TG/BG) with 1.1–2.6Ω R_DS(ON), integrated PLL for SYNC pin synchronization across 250kHz–1MHz, and independent RUN0/RUN1 enable inputs with internal 500kΩ pull-downs. Phase offset between channels is set via PHASMD pin (0°–300° relative to SYNC falling edge) per Table 1 in the datasheet.

Key Specifications

Pinout & Package

28-lead (4mm × 5mm) plastic QFN package with exposed GND pad (Pin 29). Thermal resistance θ_JA = 43°C/W, θ_JC = 3.4°C/W.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar dual-phase slave controller applications.

Compared with LTC3875IUFD#TRPBF, the LTC3874IUFD#TRPBF offers superior phase scalability and lower component count in master-slave architectures, while ISL68220IRAZ-T provides digital configurability at the expense of analog DCR sensing efficiency and added passive components.

Availability

LTC3874IUFD#TRPBF is available at Aetrix Electronics and suitable for telecom power distribution, datacenter CPU core rails, intelligent storage systems, and industrial FPGA/ASIC power supplies requiring stable component supply and long-term production continuity.

Supply support for LTC3874IUFD#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 LTC3874IUFD#TRPBF belongs to the PolyPhase® family of multi-phase DC/DC controllers, engineered specifically for high-current, low-voltage power delivery in telecom infrastructure, datacom equipment, and high-density computing systems.

FAQ

What is the primary function of the LTC3874IUFD#TRPBF in a power system?

The LTC3874IUFD#TRPBF functions exclusively as a dual-phase synchronous buck slave controller - it does not regulate output voltage independently. Instead, it extends phase count and shares current under command of a master controller (e.g., LTC3884), using ITH voltage to match per-phase current and SYNC/PHASMD for timing alignment. The LTC3874IUFD#TRPBF relies entirely on the master for voltage feedback, fault handling, and soft-start sequencing.

How does the LOWDCR pin affect current sensing performance in the LTC3874IUFD#TRPBF?

The LOWDCR pin enables the LTC3874IUFD#TRPBF's sub-milliohm DCR sensing architecture: when pulled high or left floating, it activates proprietary signal processing that improves current sense SNR by 14dB, allowing accurate measurement with inductors as low as 0.2mΩ DCR. When pulled low, standard DCR sensing applies - limiting minimum usable DCR to ~1mΩ. This setting directly impacts achievable efficiency and light-load stability in the LTC3874IUFD#TRPBF design.

Can the LTC3874IUFD#TRPBF operate without a master controller?

No - the LTC3874IUFD#TRPBF cannot operate autonomously. It lacks voltage feedback, error amplifier, and PWM oscillator independence; all critical control functions (output voltage regulation, overvoltage/overcurrent protection, soft-start) are delegated to a compatible master controller (e.g., LTC3884, LTC3875). Without ITH voltage drive and RUN signal coordination from a master, the LTC3874IUFD#TRPBF remains non-functional - it is strictly a phase-extending slave device.

What are the absolute maximum ratings for the SYNC and FREQ pins of the LTC3874IUFD#TRPBF?

The SYNC pin has an absolute maximum rating of −0.3V to INTVCC (≤5.75V), and the FREQ pin is rated −0.3V to INTVCC. Exceeding these voltages risks permanent damage. Both pins feature internal ESD protection, but sustained overvoltage - especially on FREQ, which sources a precision 10µA current - will degrade accuracy or cause latch-up. Always limit SYNC to clean CMOS-level clocks and FREQ to resistor-divider networks referenced to GND, as specified in the LTC3874IUFD#TRPBF datasheet.

How does phase alignment work between channels in the LTC3874IUFD#TRPBF?

Phase alignment in the LTC3874IUFD#TRPBF is controlled by the PHASMD pin voltage, which selects discrete phase offsets relative to the SYNC pin's falling edge: GND → 180°/0°, 1/3 INTVCC → 60°/300°, 2/3 INTVCC → 120°/240°, INTVCC → 90°/270°. This allows precise interleaving between TG0 and TG1 outputs - critical for reducing input/output ripple and thermal stress. The LTC3874IUFD#TRPBF does not auto-detect or dynamically adjust phase; alignment is static and set at power-on based on PHASMD voltage.