Analog Devices Inc. LTC3870EUF-1#TRPBF

Overview

LTC3870EUF-1#TRPBF from Analog Devices (formerly Linear Technology) is a PolyPhase® step-down slave controller designed for multiphase DC/DC systems with digital power management. It operates as a phase extender paired with the LTC3887-1 master controller, supports two PWM channels, delivers accurate inter-phase and inter-chip current sharing, and targets high-current applications up to 14V output with 4.5V–60V input.

For engineers reviewing the LTC3870EUF-1#TRPBF datasheet, LTC3870EUF-1#TRPBF pinout, LTC3870EUF-1#TRPBF application, or LTC3870EUF-1#TRPBF equivalent, this page provides verified technical context, validated pin functions, confirmed operating ranges (100kHz–1MHz SYNC, 0.5V–14V VOUT), real-world current-sharing behavior, and precise alternative selection guidance for telecom, industrial, and distributed power systems.

Technical Context

The LTC3870EUF-1#TRPBF implements peak current mode control with dual independent PWM channels synchronized via an integrated PLL to an external clock on the SYNC pin. Its ITH0/ITH1 pins receive shared current command signals from the master controller, enabling dynamic load balancing across phases without additional I²C addressing.

It features pin-programmable CCM/DCM operation via MODE0/MODE1, programmable phase offset via PHASMD (0°–300° relative to SYNC), and dual-range current limit selection (50mV/75mV) via ILIM. The device does not regulate output voltage-voltage regulation is delegated entirely to the master controller's feedback loop.

Key Specifications

Pinout & Package

Package: 24-lead (4mm × 4mm) plastic QFN (UF), exposed pad (Pin 25) soldered to PCB ground for thermal and electrical integrity.

Key Features

Applications

Equivalent & Alternatives

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

Compared with LTC3870IUF-1#TRPBF, the LTC3870EUF-1#TRPBF offers identical functionality but with relaxed temperature validation-suitable for cost-sensitive commercial applications where full industrial grading isn't required. Unlike the obsolete LTC3870EUF#TRPBF, the LTC3870EUF-1#TRPBF provides full PHASMD resolution and ILIM programmability essential for modern digital power systems.

Availability

LTC3870EUF-1#TRPBF is available at Aetrix Electronics and suitable for telecom power shelves, industrial PLC CPU supplies, and high-power GPU server VRMs requiring stable component supply, long-term lifecycle support, and traceable sourcing.

Supply support for LTC3870EUF-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 and maintains full product support, documentation, and manufacturing continuity for all Linear power ICs.

The LTC3870EUF-1#TRPBF belongs to Linear's PolyPhase® digital power management portfolio, engineered specifically to extend multiphase capability of master controllers like LTC3887-1 in high-current, high-efficiency DC/DC systems.

FAQ

What is the primary system role of the LTC3870EUF-1#TRPBF?

The LTC3870EUF-1#TRPBF functions exclusively as a PolyPhase® step-down slave controller-it does not regulate output voltage. Instead, it receives current command signals (ITH0/ITH1) and synchronization (SYNC) from a master controller like the LTC3887-1, enforcing precise per-phase current sharing while offloading voltage regulation and digital management to the master. This division of labor enables scalable, high-current power delivery without adding I²C address complexity.

Can the LTC3870EUF-1#TRPBF operate independently without a master controller?

No-the LTC3870EUF-1#TRPBF cannot operate standalone. It lacks internal voltage feedback, compensation, or PMBus interface. All critical functions-including output voltage setpoint, loop compensation, fault reporting, and digital configuration-are handled by the master controller (e.g., LTC3887-1). The LTC3870EUF-1#TRPBF relies on ITH, RUN, SYNC, and FAULT signals from that master; applying power without those connections results in undefined or non-functional behavior.

How does the PHASMD pin affect timing in a 4-phase system using LTC3870EUF-1#TRPBF?

In a 4-phase system (e.g., one LTC3887-1 + one LTC3870EUF-1#TRPBF), the PHASMD pin configures the relative phase offset between the slave's two PWM channels and the master's clock. For example, PHASMD = GND sets PWM0 at 180° and PWM1 at 0° relative to SYNC-creating a 0°/90°/180°/270° interleaved pattern across all four phases. This precise offset minimizes input capacitor RMS current and output voltage ripple, directly improving thermal performance and EMI compliance.

What happens if the EXTVCC pin is left unconnected on the LTC3870EUF-1#TRPBF?

If EXTVCC is left unconnected (or tied to GND), the LTC3870EUF-1#TRPBF defaults to powering INTVCC from VIN via its internal LDO. This is fully functional for VIN ≤15V. However, when VIN exceeds 15V, using EXTVCC (e.g., tied to a local 5V or 12V rail) reduces IC self-heating by bypassing the VIN-to-5V LDO dropout loss-lowering junction temperature by up to 25°C in 24V/48V input systems and improving long-term reliability.

Is the LTC3870EUF-1#TRPBF pin-compatible with the LTC3870EUF#TRPBF?

No-they are not pin-compatible in functional terms. While both use the same 24-pin QFN package, the LTC3870EUF#TRPBF (without "-1") is an obsolete revision with different PHASMD behavior (only 0°/180° phase options), no ILIM asymmetry support, and incompatible timing parameters. Using it in place of LTC3870EUF-1#TRPBF will cause incorrect phase alignment, failed current sharing, and potential system instability-despite identical physical pinout.