Analog Devices Inc. LTC3631EMS8E-5#PBF

Overview

LTC3631EMS8E-5#PBF 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 current at a fixed 5V output. It operates from 4.5V to 45V input, features 12µA no-load quiescent current, Burst Mode® operation, and internal overvoltage lockout protecting up to 60V surges - ideal for industrial control supplies and battery-operated devices with wide-input power rails.

For engineers reviewing the LTC3631EMS8E-5#PBF datasheet, LTC3631EMS8E-5#PBF pinout, LTC3631EMS8E-5#PBF application, or LTC3631EMS8E-5#PBF equivalent, key selection criteria include its 5V fixed output, MS8E package thermal performance (θJA = 40°C/W), programmable peak current limit (50–225mA), precise RUN pin threshold (1.21V rising), and compatibility with ceramic input/output capacitors in space-constrained designs.

Technical Context

The LTC3631EMS8E-5#PBF implements a hysteretic Burst Mode® control architecture with an internal 0.800V ±1% feedback reference and 5mV comparator hysteresis, enabling ultra-low quiescent current (12µA) while maintaining regulation across load currents from 0.1mA to 100mA. Its dual-MOSFET synchronous topology eliminates external diode losses and supports 100% duty-cycle low-dropout operation.

Input protection includes undervoltage lockout (UVLO: 3.75V to 4.50V) and overvoltage lockout (OVLO: 47V to 52V), with robust 60V absolute maximum VIN rating. The device integrates internal soft-start (0.75ms default), adjustable peak current limiting via ISET pin, and RUN/HYST pins enabling precise enable sequencing and hysteresis tuning for reliable start-up in harsh environments.

Key Specifications

Pinout & Package

The LTC3631EMS8E-5#PBF is housed in an 8-lead plastic MSOP package (MS8E) with exposed pad (Pin 9) soldered to PCB ground for optimal thermal and electrical performance. θJA = 40°C/W, θJC = 5–10°C/W.

Key Features

Applications

Equivalent & Alternatives

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

Compared with LT3692EMS8E-5#PBF, LTC3631EMS8E-5#PBF offers superior efficiency below 10mA and smaller BOM count; versus TPS62130ARGTR, it delivers essential 45V operation and 60V surge resilience for industrial and automotive use - but trades off maximum output current and switching frequency flexibility.

Availability

LTC3631EMS8E-5#PBF is available at Aetrix Electronics and suitable for industrial control supplies, 4–20mA current loops, and battery-operated instrumentation requiring stable component supply across extended temperature ranges and long production lifecycles.

Supply support for LTC3631EMS8E-5#PBF 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 semiconductors, serving industrial, automotive, communications, and healthcare markets.

The LTC3631 product line was designed specifically for high-voltage, low-quiescent-current DC/DC conversion in space- and power-constrained industrial and instrumentation systems - emphasizing robustness, simplicity, and wide-input adaptability without external compensation.

FAQ

What is the guaranteed output voltage accuracy of the LTC3631EMS8E-5#PBF over temperature?

The LTC3631EMS8E-5#PBF delivers a fixed 5V output with ±1.5% total accuracy over the full –40°C to 125°C junction temperature range. This includes initial tolerance, line regulation (0.001%/V), load regulation, and temperature drift - verified per Electrical Characteristics table on page 3 of the datasheet. The internal 0.800V ±1% feedback reference ensures tight regulation without external trimming.

Can the LTC3631EMS8E-5#PBF operate with a 3.3V input?

No, the LTC3631EMS8E-5#PBF cannot operate with a 3.3V input. Its absolute minimum operating input voltage is 4.5V, enforced by an undervoltage lockout (UVLO) that disables switching below ~3.75V (rising) and ~4.35V (falling). Attempting to power the LTC3631EMS8E-5#PBF from 3.3V will result in no regulation and zero output - a 5V or higher source is mandatory.

How does the ISET pin affect efficiency at light loads in the LTC3631EMS8E-5#PBF?

The ISET pin on the LTC3631EMS8E-5#PBF sets the peak inductor current, which directly impacts light-load efficiency. Lowering peak current (e.g., to 50mA via 0Ω resistor) reduces inductor core loss and switching loss during Burst Mode® cycles, improving efficiency below 10mA. However, excessively low peak current may increase output ripple - optimal setting balances ripple, efficiency, and transient response for the specific load profile.

Is the MS8E package of the LTC3631EMS8E-5#PBF RoHS-compliant and lead-free?

Yes, the LTC3631EMS8E-5#PBF uses a lead-free finish and is RoHS-compliant. The "#PBF" suffix explicitly denotes lead-free packaging per Analog Devices' standard marking convention. The MS8E package meets JEDEC J-STD-020 moisture sensitivity level 1 (MSL-1) and is qualified for reflow soldering at peak temperatures up to 300°C for 10 seconds, as specified in the Absolute Maximum Ratings table.

Does the LTC3631EMS8E-5#PBF require external compensation components?

No, the LTC3631EMS8E-5#PBF requires no external compensation components. Its hysteretic Burst Mode® control architecture is inherently stable and does not rely on traditional voltage-mode or current-mode loop compensation. Only three external components - input capacitor, output capacitor, and inductor - are needed for basic operation of the fixed 5V version, significantly simplifying design and reducing BOM count.