Analog Devices Inc. LT8618JDDB-3.3#TRMPBF

Overview

LT8618JDDB-3.3#TRMPBF from Analog Devices is a monolithic synchronous step-down DC/DC converter delivering 100mA at fixed 3.3V output, operating from 3.4V to 60V input (65V transient), with 2.5µA quiescent current in Burst Mode and 35ns minimum on-time. It features internal compensation, soft-start/tracking, power-good flag, and AEC-Q100 qualification for automotive housekeeping supplies.

For engineers reviewing the LT8618JDDB-3.3#TRMPBF datasheet, LT8618JDDB-3.3#TRMPBF pinout, LT8618JDDB-3.3#TRMPBF application, or LT8618JDDB-3.3#TRMPBF equivalent, key selection criteria include its –40°C to 150°C junction temperature rating, DFN-10 (3mm × 2mm) package with exposed pad, 3.3V ±3% output accuracy, and compatibility with high-input-voltage industrial sensor and 4–20mA loop designs.

Technical Context

The LT8618JDDB-3.3#TRMPBF implements constant-frequency current-mode control with integrated top/bottom NMOS switches, enabling precise regulation across wide input ranges. Its 35ns minimum on-time supports high step-down ratios (e.g., 48V to 3.3V), while internal compensation eliminates external loop components.

Burst Mode operation reduces quiescent current to 2.5µA at light loads without compromising regulation accuracy, and the PG flag asserts when VOUT is within ±7.5% of 3.3V. Thermal shutdown and UVLO protection ensure robust operation in harsh environments.

Key Specifications

Pinout & Package

LT8618JDDB-3.3#TRMPBF uses a 10-lead 3mm × 2mm plastic DFN package with exposed thermal pad (Pin 11 = GND), optimized for high-power-density layouts and thermal performance (θJA = 76°C/W).

Key Features

Applications

Equivalent & Alternatives

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

Compared with LT8618IDDB-3.3#TRMPBF and LT8618EDDB-3.3#TRMPBF, the LT8618JDDB-3.3#TRMPBF provides guaranteed operation up to +150°C junction temperature and full AEC-Q100 qualification - essential for under-hood automotive systems and high-reliability industrial deployments where thermal derating margins are constrained.

Availability

LT8618JDDB-3.3#TRMPBF is available at Aetrix Electronics and suitable for automotive housekeeping supplies, industrial sensor nodes, and 4–20mA current loop transmitters requiring stable component supply across extended temperature ranges and long production lifecycles.

Supply support for LT8618JDDB-3.3#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 is a global leader in high-performance analog, mixed-signal, and digital signal processing semiconductors, serving industrial, automotive, communications, and healthcare markets.

The LT8618 family was designed specifically for high-input-voltage, low-quiescent-current step-down regulation in space-constrained and thermally demanding applications such as automotive subsystems and industrial IoT edge nodes.

FAQ

What is the maximum continuous input voltage rating for the LT8618JDDB-3.3#TRMPBF?

The LT8618JDDB-3.3#TRMPBF supports continuous operation up to 60V on the VIN pin, with absolute maximum rating of 65V for transient conditions only. This enables reliable use in 48V automotive and industrial systems where load-dump spikes may occur. The device's internal protection circuitry maintains regulation and prevents damage during brief overvoltage events.

Does the LT8618JDDB-3.3#TRMPBF require external feedback resistors to set the 3.3V output?

No, the LT8618JDDB-3.3#TRMPBF integrates the feedback divider for its fixed 3.3V output - the OUT pin connects directly to the internal reference network. No external resistors are needed, reducing BOM count and eliminating resistor tolerance errors that affect output accuracy in adjustable regulators.

How does the LT8618JDDB-3.3#TRMPBF achieve 2.5µA quiescent current?

The LT8618JDDB-3.3#TRMPBF achieves 2.5µA quiescent current by entering Burst Mode operation at light loads: it disables switching and shuts down non-essential internal circuitry between energy bursts, while maintaining regulation via periodic sampling. This behavior is inherent to the part and requires no external configuration - it activates automatically below ~1mA load.

Is the LT8618JDDB-3.3#TRMPBF pin-compatible with other members of the LT8618 family?

Yes, the LT8618JDDB-3.3#TRMPBF shares identical pinout and package (10-lead DFN, 3mm × 2mm) with LT8618EDDB-3.3#TRMPBF and LT8618IDDB-3.3#TRMPBF. All three variants use the same OUT pin function, TR/SS soft-start, EN/UV enable, and PG flag - enabling drop-in replacement across temperature grades without PCB redesign.

What thermal performance can be expected from the LT8618JDDB-3.3#TRMPBF in a typical 2-layer PCB layout?

In a standard 2-layer PCB with 1-in² 2-oz copper thermal pad connected to the exposed GND pad (Pin 11), the LT8618JDDB-3.3#TRMPBF achieves θJA ≈ 76°C/W. At 100mA load and 24VIN → 3.3VOUT, power dissipation is ~2.1W, resulting in ~160°C junction rise above ambient - well within its 150°C max rating only with adequate airflow or heatsinking; derating is recommended for sealed enclosures.