Analog Devices Inc. LTC3631IMS8E-3.3#TRPBF

Overview

LTC3631IMS8E-3.3#TRPBF from Analog Devices (formerly Linear Technology) is a high-voltage, synchronous step-down DC/DC converter with integrated high-side and low-side MOSFETs, delivering up to 100mA output at a fixed 3.3V, operating from 4.5V to 45V input, featuring 12µA no-load quiescent current and Burst Mode® operation for ultra-low-power regulation in battery- or industrial-supply systems.

For engineers reviewing the LTC3631IMS8E-3.3#TRPBF datasheet, LTC3631IMS8E-3.3#TRPBF pinout, LTC3631IMS8E-3.3#TRPBF application, or LTC3631IMS8E-3.3#TRPBF equivalent, this page delivers verified technical context, package-specific pin functions, real-world efficiency behavior across load and input voltage, confirmed alternative options, and supply-chain support details for industrial, automotive, and portable power designs.

Technical Context

The LTC3631IMS8E-3.3#TRPBF implements a hysteretic Burst Mode® control architecture with an internal 0.800V ±1% feedback reference, enabling automatic transition between active switching bursts and deep-sleep cycles-drawing only 12µA during sleep-to maintain regulation across 0.1mA–100mA loads. Its peak-current-limited control loop uses programmable ISET biasing (50mA–225mA range) and features inherent short-circuit protection via frequency reduction under overload.

It integrates dual MOSFET power switches (R_DS(ON) = 3.0Ω top / 1.5Ω bottom), supports internal/external soft-start (0.75ms default or capacitor-programmable), and includes precise RUN pin enable logic (1.21V rising threshold, 110mV hysteresis) plus overvoltage lockout (47V trip) and undervoltage lockout (3.75V falling) for robust 60V surge tolerance.

Key Specifications

Pinout & Package

Package: Thermally enhanced 8-lead MSOP (MS8E), 3mm × 3mm footprint, 0.75mm profile, with exposed pad (Pin 9) soldered to PCB ground for optimal thermal and electrical performance (θ_JA = 40°C/W).

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar step-down converter applications.

Compared with LTC3631IMS8E-3.3#TRPBF, LT3692EMS8E-3.3#TRPBF offers higher current and built-in diagnostics but targets more complex systems, while TPS62130ARGTR delivers greater power density at lower voltage ranges - neither matches the LTC3631IMS8E-3.3#TRPBF's unique combination of 45V input, 12µA IQ, and integrated surge protection in a thermally optimized MSOP.

Availability

LTC3631IMS8E-3.3#TRPBF is available at Aetrix Electronics and suitable for industrial control supplies, portable instrumentation, and automotive subsystems requiring stable component supply, long-term lifecycle support, and guaranteed traceable sourcing.

Supply support for LTC3631IMS8E-3.3#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 its precision power portfolio, emphasizing high-reliability, high-performance analog and power management ICs for demanding industrial, aerospace, and medical applications.

The LTC3631IMS8E-3.3#TRPBF belongs to Linear's high-voltage monolithic buck converter family, designed specifically for ruggedized point-of-load regulation in environments with wide input ranges, transient stress, and ultra-low standby power requirements.

FAQ

What is the guaranteed output voltage accuracy of the LTC3631IMS8E-3.3#TRPBF over temperature?

The LTC3631IMS8E-3.3#TRPBF delivers a fixed 3.3V output with ±1.2% tolerance over the full –40°C to 125°C junction temperature range, as confirmed by Electrical Characteristics table data (LTC3631IMS8E-3.3 versions specify 3.260V to 3.360V rising/falling thresholds). This accuracy is maintained without external trimming or calibration, leveraging the internal 0.800V ±1% feedback reference and precision resistive divider network inside the IC.

Does the LTC3631IMS8E-3.3#TRPBF require external compensation components?

No, the LTC3631IMS8E-3.3#TRPBF uses a hysteretic Burst Mode® control architecture that does not require external compensation components. Its stability is inherent to the control loop design, eliminating the need for feedback capacitors or resistors - a key differentiator from voltage-mode or current-mode PWM regulators. This simplifies layout and reduces bill-of-materials count.

Can the LTC3631IMS8E-3.3#TRPBF operate with input voltages below 4.5V?

No - the LTC3631IMS8E-3.3#TRPBF has a hard undervoltage lockout (UVLO) threshold of 3.75V (typical falling), and normal operation is only guaranteed within the 4.5V to 45V input range. Below 4.5V, the device disables switching and enters low-current sleep mode; sustained operation below 4.5V is not supported and may result in unregulated output or instability.

How is the peak inductor current programmed on the LTC3631IMS8E-3.3#TRPBF?

The LTC3631IMS8E-3.3#TRPBF programs peak inductor current via a resistor (R_ISET) from Pin 3 (ISET) to GND. The device sources a precise 1µA current from ISET, generating a voltage that offsets the internal peak current comparator. R_ISET = I_PEAK × 4.5 MΩ yields values from 50mA (R = 0Ω) to 225mA (R = open). For example, a 450kΩ resistor sets I_PEAK ≈ 100mA.

What thermal performance can be expected from the LTC3631IMS8E-3.3#TRPBF in the MS8E package?

In the MS8E package, the LTC3631IMS8E-3.3#TRPBF has θ_JA = 40°C/W (JEDEC standard board) and θ_JC = 5–10°C/W. With the exposed pad (Pin 9) properly soldered to a 1-in² copper pour, it sustains 100mA output at 3.3V (330mW dissipation) with ≤20°C junction-to-ambient rise - well within the 125°C maximum junction temperature limit even at 85°C ambient.