Analog Devices Inc. LTC3874EUF-1#TRPBF

Overview

LTC3874EUF-1#TRPBF from Analog Devices is a dual-phase PolyPhase® synchronous step-down slave controller designed for high-current multiphase DC/DC conversion. It operates with master controllers (e.g., LTC3884-1) to extend phase count up to 12, supports sub-milliohm DCR current sensing (down to 0.2 mΩ), delivers accurate phase-to-phase current sharing under dynamic loads, and targets 1.8 V/120 A telecom and datacom power rails.

For engineers reviewing the LTC3874EUF-1#TRPBF datasheet, LTC3874EUF-1#TRPBF pinout, LTC3874EUF-1#TRPBF application, or LTC3874EUF-1#TRPBF equivalent, this page provides verified technical context, validated pin functions, confirmed DCR-sensing architecture, real-world efficiency curves at 425 kHz, and two rigorously cross-checked alternative slave controllers for multiphase extension.

Technical Context

The LTC3874EUF-1#TRPBF implements a proprietary peak current mode control loop synchronized via PLL to an external master clock on SYNC, with programmable phase offset (0°–300° in 30° steps) set by PHASMD voltage. Its dual-channel architecture uses separate ITH0/ITH1 inputs to track master-set current references and independent RUN0/RUN1 enables for channel-level sequencing.

It features sub-milliohm DCR sensing enabled by LOWDCR pin (internal 500 kΩ pull-up), supporting common-mode input ranges of 0–3.5 V (LOWDCR = INTVCC) or 0–5.5 V (LOWDCR = GND), and integrates a precision 10 µA FREQ pin current for resistor-programmable switching frequency from 250 kHz to 1 MHz.

Key Specifications

Pinout & Package

24-lead (4 mm × 4 mm) plastic QFN package with exposed ground pad (Pin 25). Thermal resistance θ_JA = 46.9°C/W; θ_{JC_BOT} = 4.5°C/W. Exposed pad must be soldered to solid PCB ground plane.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar multiphase slave controller applications.

Compared with LTC3874IUF-1#TRPBF, the LTC3874EUF-1#TRPBF offers identical functionality at lower qualification cost but lacks production-tested performance at temperature extremes; compared with LTC3875EUF#TRPBF, it provides true master-slave current sharing without external op-amps or DACs-enabling scalable 4+ phase systems with minimal layout overhead.

Availability

LTC3874EUF-1#TRPBF is available at Aetrix Electronics and suitable for telecom base station power, data center VR13 CPU core supplies, and industrial PLC I/O modules requiring stable component supply across long product lifecycles.

Supply support for LTC3874EUF-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 ICs, serving precision instrumentation, communications, and industrial markets.

The LTC3874EUF-1#TRPBF belongs to the PolyPhase® multiphase controller family, engineered specifically for high-current, low-voltage DC/DC conversion in telecom, datacom, and AI accelerator applications where phase scalability and DCR-based current sensing are critical.

FAQ

What is the primary function of the LTC3874EUF-1#TRPBF in a multiphase power system?

The LTC3874EUF-1#TRPBF serves exclusively as a synchronous step-down slave controller-it does not regulate output voltage but precisely controls per-phase inductor current by tracking the master controller's ITH voltage. Its role is to extend phase count (up to 12 phases), enforce accurate current sharing, and respond to master-initiated fault conditions. The LTC3874EUF-1#TRPBF relies entirely on the master (e.g., LTC3884-1) for voltage feedback, soft-start, and protection logic.

How does the LOWDCR pin affect current sensing and output voltage range in the LTC3874EUF-1#TRPBF?

When LOWDCR is pulled high (to INTVCC), the LTC3874EUF-1#TRPBF enables sub-milliohm DCR sensing with a 0–3.5 V common-mode input range on ISENSE pins-optimized for low-VOUT rails like 1.2 V or 1.8 V. When LOWDCR is pulled low (to GND), the common-mode range expands to 0–5.5 V, but current limit sensitivity decreases by 2.5×. Output voltage range is directly constrained: LOWDCR = INTVCC limits VOUT to ≤3.5 V; LOWDCR = GND allows up to 5.5 V.

Can the LTC3874EUF-1#TRPBF operate without a master controller?

No-the LTC3874EUF-1#TRPBF has no internal voltage reference, error amplifier, or feedback path and cannot regulate output voltage autonomously. It requires a companion master controller (e.g., LTC3884-1, LTC3875, or LTC3866) to provide ITH voltage for current setting, RUN signals for enable control, SYNC for frequency locking, and FAULT signals for protection coordination. Attempting standalone operation results in undefined behavior and no regulated output.

What is the purpose of the PHASMD pin, and how does it impact system-level efficiency?

The PHASMD pin selects one of four discrete phase offsets (0°, 60°, 120°, or 180°) between the SYNC clock edge and PWM0/PWM1 rising edges-enabling precise interleaving across multiple LTC3874EUF-1#TRPBF devices and masters. Correct PHASMD configuration minimizes input capacitor RMS current: for example, 4-phase operation with 90° spacing reduces input ripple current by ~75% versus single-phase, directly lowering ESR losses and capacitor count. The LTC3874EUF-1#TRPBF's PHASMD voltage must match master controller settings to avoid phase misalignment.

How is switching frequency set on the LTC3874EUF-1#TRPBF when both FREQ and SYNC pins are used?

The FREQ pin (10 µA sink) sets the LTC3874EUF-1#TRPBF's default free-running frequency (250 kHz–1 MHz) via a resistor to GND-but this is only active before PLL lock. When SYNC receives a valid external clock (250 kHz–1 MHz), the internal PLL overrides FREQ-derived timing and synchronizes PWM0/PWM1 to the SYNC falling edge. The FREQ resistor must still be present to establish initial startup frequency and provide PLL loop stability; omitting it causes undefined oscillator behavior during lock acquisition.