Analog Devices Inc. LT8618JDDB-3.3#TRPBF

Overview

LT8618JDDB-3.3#TRPBF 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 ±7.5% power-good flag accuracy, internal compensation, soft-start, and AEC-Q100 qualification for automotive housekeeping supplies.

For engineers reviewing the LT8618JDDB-3.3#TRPBF datasheet, LT8618JDDB-3.3#TRPBF pinout, LT8618JDDB-3.3#TRPBF application, or LT8618JDDB-3.3#TRPBF equivalent, key selection criteria include its 150°C junction temperature rating, DFN-10 (3mm × 2mm) package with exposed thermal pad, fixed-output architecture eliminating external feedback resistors, and compatibility with high-input-voltage industrial sensor and 4–20mA loop designs.

Technical Context

The LT8618JDDB-3.3#TRPBF implements constant-frequency current-mode control with integrated top and bottom NMOS power switches, enabling high efficiency across wide load ranges. Its 35ns minimum on-time supports high VIN/VOUT ratios (e.g., 48V-to-3.3V) without pulse-skipping instability.

Burst Mode operation reduces quiescent current to 2.5µA while maintaining regulation, and the PG pin provides ±7.5% output voltage monitoring independent of EN/UV state. Thermal shutdown and UVLO protection are built-in, with guaranteed operation from –40°C to 150°C junction temperature.

Key Specifications

Pinout & Package

LT8618JDDB-3.3#TRPBF 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 converter applications.

Compared with LT8618IDDB-3.3#TRPBF, the LT8618JDDB-3.3#TRPBF enables higher ambient operation without derating; versus LT8618ARDDBM-3.3#WTRPBF, it offers identical thermal performance in a standard DFN, simplifying layout and procurement where AOI is not mandated.

Availability

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

Supply support for LT8618JDDB-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 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 delivers compact, high-efficiency step-down conversion for space-constrained, high-input-voltage applications-designed specifically for automotive subsystems, industrial sensors, and precision analog power rails.

FAQ

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

The LT8618JDDB-3.3#TRPBF supports 60V continuous input voltage, with absolute maximum rating of 65V for transient conditions only. This makes it suitable for 48V industrial and automotive systems where load dump spikes may occur. Operation above 60V continuously risks permanent damage, and design margins should maintain VIN ≤60V under all steady-state conditions.

Does the LT8618JDDB-3.3#TRPBF require external feedback resistors to set its output voltage?

No, the LT8618JDDB-3.3#TRPBF has an internally trimmed fixed 3.3V output, so no external feedback resistors are required. The OUT pin connects directly to the output capacitor and load. This simplifies design, improves accuracy over temperature (±3% over –40°C to 150°C), and eliminates resistor tolerance and layout-induced errors present in adjustable versions like the LT8618.

How does the power-good (PG) flag behave during enable/disable transitions on the LT8618JDDB-3.3#TRPBF?

The PG pin on the LT8618JDDB-3.3#TRPBF remains valid and functional whenever VIN exceeds 3.4V-even if EN/UV is held low. It asserts high only when VOUT is within ±7.5% of 3.3V and no fault (e.g., thermal shutdown) is present. This allows reliable system sequencing independent of enable control, critical for multi-rail power-up coordination in automotive and industrial controllers.

Can the LT8618JDDB-3.3#TRPBF operate efficiently at very light loads, such as 100µA?

Yes, the LT8618JDDB-3.3#TRPBF enters Burst Mode operation below ~1mA load, achieving 2.5µA quiescent current at 48VIN→3.3VOUT. Efficiency remains >75% down to 100µA output current, making it ideal for always-on IoT sensors and battery-backed systems where standby power is critical to operational lifetime.

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

With the exposed thermal pad (Pin 11) properly soldered to a ≥1cm² copper pour on a standard 2-layer FR-4 PCB, the LT8618JDDB-3.3#TRPBF achieves θJA ≈ 76°C/W. At 100mA output and 24VIN→3.3VOUT, power dissipation is ~200mW, resulting in ~15°C junction-to-ambient rise-well within its 150°C max rating. For higher ambient or denser layouts, adding thermal vias under the pad further improves performance.