Analog Devices Inc. LTC3872ITS8-1#TRPBF

Overview

LTC3872ITS8-1#TRPBF from Analog Devices (formerly Linear Technology) is a constant-frequency current-mode boost DC/DC controller driving an external N-channel MOSFET without requiring a sense resistor. It operates from 2.75V to 9.8V input, delivers up to 60V output, achieves ±1.5% V_OUT accuracy, and features 550kHz switching for compact inductor sizing - used in telecom power supplies and IP phone systems.

For engineers reviewing the LTC3872ITS8-1#TRPBF datasheet, LTC3872ITS8-1#TRPBF pinout, LTC3872ITS8-1#TRPBF application, or LTC3872ITS8-1#TRPBF equivalent, key selection criteria include No RSENSE™ operation, adjustable current limit via IPRG pin, internal soft-start, pulse-skipping at light load, and –40°C to 125°C junction temperature rating.

Technical Context

The LTC3872ITS8-1#TRPBF implements a No RSENSE™ current-sensing architecture that monitors voltage drop across the power MOSFET's R_DS(ON), eliminating external sense resistors and improving efficiency. Its constant-frequency 550kHz oscillator enables predictable EMI behavior and supports CCM/DCM operation with internal slope compensation for duty cycles >50%.

It uses a transconductance error amplifier with ITH pin as compensation node and current comparator threshold set by ITH voltage. The RUN/SS pin provides shutdown control and optional external soft-start via capacitor charging at 0.7µA, while undervoltage lockout disables operation below 2.3V VIN.

Key Specifications

Pinout & Package

Package: 8-lead TSOT-23 (ThinSOT™), 1mm height, exposed pad (GND), rated for –40°C to 125°C junction temperature.

Key Features

Applications

Equivalent & Alternatives

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

Compared with LTC3872ITS8-1#TRPBF, the E-grade variant trades thermal robustness for lower cost in benign environments, while the DFN variant improves thermal dissipation at the expense of larger footprint and reflow profile complexity.

Availability

LTC3872ITS8-1#TRPBF is available at Aetrix Electronics and suitable for telecom power supplies, IP phone power supplies, and 42V automotive systems requiring stable component supply, long-term lifecycle support, and guaranteed industrial-temperature operation.

Supply support for LTC3872ITS8-1#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 legacy Linear parts including the LTC3872 family.

The LTC3872 series was designed as a high-efficiency, low-component-count boost controller targeting space- and efficiency-critical DC/DC conversion in portable, telecom, and industrial equipment.

FAQ

What is the maximum output voltage supported by the LTC3872ITS8-1#TRPBF?

The LTC3872ITS8-1#TRPBF supports output voltages up to 60V, as confirmed by its SW pin absolute maximum rating of –0.3V to 60V. This enables use in high-voltage bias generation applications such as telecom 48V systems or industrial sensor excitation, provided the external MOSFET and diode are rated accordingly. The controller itself does not regulate above 60V.

Does the LTC3872ITS8-1#TRPBF require an external current-sense resistor?

No, the LTC3872ITS8-1#TRPBF implements Linear's No RSENSE™ architecture and senses current via the voltage drop across the external N-channel MOSFET's R_DS(ON). This eliminates the need for a discrete sense resistor, reducing power loss, board area, and component count. An external resistor may be used optionally for improved accuracy or when MOSFET R_DS(ON) variation is unacceptable.

What is the purpose of the IPRG pin on the LTC3872ITS8-1#TRPBF?

The IPRG pin on the LTC3872ITS8-1#TRPBF selects the peak current limit threshold: grounding it sets ~80mV, floating sets ~150mV, and connecting to VIN sets ~250mV (all typical values, varying with grade). This allows designers to match the current limit to the chosen MOSFET's R_DS(ON) and required load current without changing external components - a key enabler of the No RSENSE™ design.

Can the LTC3872ITS8-1#TRPBF operate in discontinuous conduction mode (DCM)?

Yes, the LTC3872ITS8-1#TRPBF naturally transitions into discontinuous conduction mode at light loads due to its current-mode architecture and pulse-skipping behavior. The datasheet confirms operation down to zero load current with cycle skipping, maintaining regulation while minimizing audible noise and RF emissions - critical for battery-powered and noise-sensitive applications using the LTC3872ITS8-1#TRPBF.

What is the thermal resistance (θ_JA) of the LTC3872ITS8-1#TRPBF in its TSOT-23 package?

The LTC3872ITS8-1#TRPBF in the 8-lead TSOT-23 package has a junction-to-ambient thermal resistance (θ_JA) of 195°C/W, as specified in the Absolute Maximum Ratings table. This value assumes standard JEDEC 2-layer board conditions; actual thermal performance improves significantly with proper PCB layout - especially soldering the exposed pad to a large GND copper area.