Analog Devices Inc. LT8609AEDDM-3.3#TRPBF

Overview

LT8609AEDDM-3.3#TRPBF from Analog Devices is a 42V, 3A synchronous step-down regulator in a 10-lead 3mm × 3mm side-wettable DFN package, featuring 2.5µA quiescent current in Burst Mode®, fixed 3.3V output, and internal compensation for fast transient response. It delivers high efficiency (>93% at 1A, 12V_IN to 3.3V_OUT) and supports spread-spectrum EMI reduction via SYNC pin - ideal for automotive infotainment power rails and low-power industrial sensors.

For engineers reviewing the LT8609AEDDM-3.3#TRPBF datasheet, LT8609AEDDM-3.3#TRPBF pinout, LT8609AEDDM-3.3#TRPBF application, or LT8609AEDDM-3.3#TRPBF equivalent, key selection criteria include its guaranteed ±7.5% power-good accuracy on VOUT, 45ns minimum on-time for high VIN/VOUT ratios, AEC-Q100 qualification (E-grade, –40°C to 125°C), and compatibility with small 2.2µH inductors at 2MHz switching.

Technical Context

This monolithic current-mode buck converter uses peak-current control with internal 0.782V reference (adjusted to 3.3V via internal 5.9MΩ divider) and frequency set by external RT resistor or SYNC input (200kHz–2.2MHz). Its Burst Mode® operation maintains <10mV_P-P ripple while drawing only 46µA at 100µA load (VIN=8V), and it implements frequency foldback during start-up to limit inrush.

The LT8609A variant features slower switch edges versus LT8609/LT8609B to reduce EMI emissions, and its PG pin asserts when VOUT reaches ±7.5% of 3.3V - distinct from adjustable versions that monitor FB at ±8.5%. TR/SS enables soft-start and tracking with 2µA internal pull-up, and EN/UV has precise 1.05V rising threshold with 50mV hysteresis.

Key Specifications

Pinout & Package

LT8609AEDDM-3.3#TRPBF is housed in a 10-lead 3mm × 3mm plastic side-wettable DFN package (DDM) with exposed thermal pad (Pin 11 = GND), θ_JA = 45°C/W. The package supports automated optical inspection (AOI) of solder joints via side-wettable flanks.

Key Features

Applications

Equivalent & Alternatives

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

Compared with LT8609EMSE#TRPBF, LT8609AEDDM-3.3#TRPBF offers superior manufacturability via side-wettable leads and lower thermal resistance, while LT8609AEDDM-5#TRPBF serves distinct voltage requirements - neither is pin-compatible nor functionally substitutable without schematic revision.

Availability

LT8609AEDDM-3.3#TRPBF is available at Aetrix Electronics and suitable for automotive infotainment systems, industrial IoT sensor nodes, and medical point-of-care devices requiring stable component supply across extended temperature ranges and long production lifecycles.

Supply support for LT8609AEDDM-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 LT8609 family was designed specifically for high-input-voltage, ultralow-quiescent-current DC/DC conversion in space-constrained and thermally demanding environments - especially automotive and battery-powered applications.

FAQ

What is the guaranteed output voltage tolerance for LT8609AEDDM-3.3#TRPBF over temperature?

The LT8609AEDDM-3.3#TRPBF guarantees 3.3V output within ±1.5% over its full operating junction temperature range of –40°C to 125°C. This is confirmed in the Electrical Characteristics table (page 4), where VOUT = 3.291V to 3.309V at 100mA load and VIN = 8V - tighter than standard 3.3V regulators and essential for powering voltage-sensitive interfaces like USB PHYs or high-speed SerDes.

Does LT8609AEDDM-3.3#TRPBF require external feedback resistors?

No, LT8609AEDDM-3.3#TRPBF does not require external feedback resistors. It integrates a precision 5.9MΩ internal resistor divider that fixes the output to 3.3V - eliminating component count, layout sensitivity, and drift errors associated with external dividers. This is explicitly stated in the PIN FUNCTIONS section (page 11): "The LT8609A-3.3 regulates to VOUT pin to 3.3V. This pin connects a 5.9MΩ internal feedback divider."

How does the PG pin behave on LT8609AEDDM-3.3#TRPBF during startup and fault conditions?

On LT8609AEDDM-3.3#TRPBF, the PG pin remains low until VOUT reaches within ±7.5% of 3.3V (i.e., 3.05V–3.55V) and no fault (overcurrent, thermal shutdown, or UVLO) is present. Unlike adjustable variants that monitor FB at ±8.5%, this fixed-output version monitors VOUT directly - providing faster, more accurate power-good assertion aligned with actual rail voltage. PG is valid whenever VIN > 3.2V, independent of EN/UV state.

Can LT8609AEDDM-3.3#TRPBF synchronize to an external clock, and what are the voltage requirements?

Yes, LT8609AEDDM-3.3#TRPBF can synchronize to an external clock via the SYNC pin. To enable synchronization, apply a logic-high signal between 2.7V and 3.2V (with INTVCC = 3.5V) - per Absolute Maximum Ratings (page 2) and PIN FUNCTIONS (page 11). Driving SYNC with 3.3V also activates spread-spectrum modulation, reducing EMI peaks by dithering the switching frequency ±10% at 1–6kHz.

What thermal performance can be expected from the DFN package of LT8609AEDDM-3.3#TRPBF?

The LT8609AEDDM-3.3#TRPBF in its 3mm × 3mm side-wettable DFN package has θ_JA = 45°C/W and θ_JC = 10°C/W (page 2). With a 2-in² 2-oz copper thermal pad connected to the exposed GND pad, it sustains 3A continuous output at 12V_IN/3.3V_OUT up to +85°C ambient - verified in Typical Performance Characteristic Figure G31 (page 9). This exceeds MSOP alternatives and supports convection-cooled automotive modules.