Analog Devices Inc. LTC3872HDDB-1#TRMPBF

Overview

LTC3872HDDB-1#TRMPBF 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% voltage accuracy, and supports 550kHz switching for compact inductor sizing - deployed in automotive 42V systems and industrial 24V controls.

For engineers reviewing the LTC3872HDDB-1#TRMPBF datasheet, LTC3872HDDB-1#TRMPBF pinout, LTC3872HDDB-1#TRMPBF application, or LTC3872HDDB-1#TRMPBF equivalent, key selection criteria include its No RSENSE architecture, –40°C to 150°C junction temperature rating, adjustable current limit via IPRG pin, internal soft-start, and compatibility with high-voltage MOSFET sensing in boost, SEPIC, and flyback topologies.

Technical Context

The LTC3872HDDB-1#TRMPBF implements a No RSENSE current-sensing architecture that monitors the voltage drop across the power MOSFET's R_DS(ON), eliminating external sense resistors and improving efficiency. Its constant-frequency 550kHz oscillator enables precise timing control and predictable EMI behavior.

It features current-mode control with internal slope compensation, supporting duty cycles up to 90% and stable operation above 50% duty cycle without subharmonic oscillation. The ITH pin serves as the error amplifier output and current threshold control node, while RUN/SS provides shutdown and optional external soft-start via capacitor charging.

Key Specifications

Pinout & Package

Package: 8-lead (3mm × 2mm) plastic DFN with exposed pad (Pin 9 = GND). Requires soldering of exposed pad for thermal and electrical performance.

Key Features

Applications

Equivalent & Alternatives

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

Compared with LTC3872IDDB-1#TRPBF and LTC3872EDDB-1#TRPBF, the LTC3872HDDB-1#TRMPBF provides the highest junction temperature rating (150°C), making it the sole option qualified for sustained operation in thermally aggressive automotive and industrial environments without derating.

Availability

LTC3872HDDB-1#TRMPBF is available at Aetrix Electronics and suitable for automotive 42V systems, industrial 24V controls, and telecom power supplies requiring stable component supply across extended temperature ranges and long production lifecycles.

Supply support for LTC3872HDDB-1#TRMPBF 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 its precision analog and power management portfolio with rigorous automotive and industrial qualification standards.

The LTC3872HDDB-1#TRMPBF belongs to the LTC3872 family of No RSENSE boost controllers, designed specifically for high-efficiency, high-voltage-ratio DC/DC conversion in space- and thermally constrained applications where sense-resistor losses and board area are critical.

FAQ

What is the maximum output voltage supported by the LTC3872HDDB-1#TRMPBF?

The LTC3872HDDB-1#TRMPBF supports output voltages up to 60V, as confirmed by the absolute maximum rating for the SW pin. This enables use in high-ratio boost applications such as 3.3V-to-24V, 5V-to-48V, and 12V-to-42V conversion, provided the external MOSFET and diode are rated accordingly. The controller itself does not regulate beyond the feedback divider setting, but the 60V SW rating ensures safe operation under transient and ringing conditions.

How does the No RSENSE architecture in the LTC3872HDDB-1#TRMPBF improve efficiency?

The LTC3872HDDB-1#TRMPBF eliminates the external current-sense resistor by measuring the voltage drop across the R_DS(ON) of the external N-channel MOSFET. This removes I²R losses associated with discrete sense resistors - especially beneficial at high output currents - and reduces board area and component count. Efficiency gains are most pronounced at loads above 1A, where typical sense-resistor losses would exceed 100mW.

What is the purpose of the IPRG pin on the LTC3872HDDB-1#TRMPBF?

The IPRG pin on the LTC3872HDDB-1#TRMPBF selects the peak current limit threshold: 80mV (IPRG = GND), 145mV (IPRG = floating), or 240mV (IPRG = VIN). This directly sets the maximum allowable voltage drop across the MOSFET during conduction, thereby defining the peak inductor current without external components. It enables flexible MOSFET selection and current-limit tuning across operating conditions.

Can the LTC3872HDDB-1#TRMPBF operate in discontinuous conduction mode (DCM)?

Yes, the LTC3872HDDB-1#TRMPBF supports both continuous and discontinuous conduction modes. At light loads, it enters pulse-skipping mode to maintain regulation while reducing switching frequency - a behavior distinct from hard DCM but achieving similar light-load efficiency benefits. The controller does not force CCM; inductor selection and load determine the actual conduction mode.

What is the thermal performance difference between the DDB and TSOT-23 packages for the LTC3872HDDB-1#TRMPBF?

The LTC3872HDDB-1#TRMPBF in the 3mm × 2mm DFN (DDB) package has θ_JA = 76°C/W, significantly lower than the TSOT-23 variant's θ_JA = 195°C/W. This allows ~2.5× higher power dissipation before reaching 150°C junction temperature under identical PCB layout conditions, making the DDB package essential for high-current or high-ambient applications.