Analog Devices Inc. LT8609AEDDM-5#PBF

Overview

LT8609AEDDM-5#PBF from Analog Devices is a 42V, 3A synchronous step-down regulator with fixed 5V output, 2.5µA quiescent current in Burst Mode, 45ns minimum on-time, and spread spectrum EMI reduction. It operates from 3.0V to 42V input and delivers regulated 5V at up to 3A continuous load for automotive infotainment power rails.

For engineers reviewing the LT8609AEDDM-5#PBF datasheet, LT8609AEDDM-5#PBF pinout, LT8609AEDDM-5#PBF application, or LT8609AEDDM-5#PBF equivalent, key selection criteria include its fixed 5V output accuracy (±7.5% PG threshold), side-wettable DFN-10 package for automated optical inspection, AEC-Q100 qualification, and SYNC-enabled low-EMI operation - all critical for automotive and industrial DC/DC designs requiring stable light-load efficiency.

Technical Context

The LT8609AEDDM-5#PBF uses peak current mode control with internal compensation and a programmable oscillator (200kHz–2.2MHz via RT resistor). Its fixed 5V output eliminates external feedback resistors, while the VOUT pin directly regulates to 4.97–5.03V at 100mA load.

Burst Mode operation enables ultralow IQ (2.5µA at 12VIN→5VOUT no load) with <10mVP-P ripple; spread spectrum modulation (1–6kHz) is enabled when SYNC is tied to 3.2–5.0V, reducing EMI peaks without sacrificing regulation performance.

Key Specifications

Pinout & Package

LT8609AEDDM-5#PBF is housed in a 10-lead (3mm × 3mm) plastic side-wettable DFN package with exposed thermal pad (Pin 11 = GND). The package supports automated optical inspection (AOI) and offers θJA = 45°C/W.

Key Features

Applications

Equivalent & Alternatives

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

Compared with LT8609AEMSE-5#PBF, the LT8609AEDDM-5#PBF trades slightly higher thermal resistance for AOI-enabled process control; compared with LT8609AEDDM-3.3#PBF, it delivers higher output voltage for 5V-tolerant interfaces while maintaining identical footprint and EMI performance.

Availability

LT8609AEDDM-5#PBF is available at Aetrix Electronics and suitable for automotive infotainment systems, GSM transceiver modules, and industrial sensor hubs requiring stable component supply with AEC-Q100 assurance and side-wettable DFN manufacturability.

Supply support for LT8609AEDDM-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 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 is designed for high-efficiency, low-EMI DC/DC conversion in space-constrained and noise-sensitive applications - especially automotive and portable electronics where ultralow quiescent current and robust transient response are mandatory.

FAQ

What is the output voltage tolerance of the LT8609AEDDM-5#PBF under full load and temperature?

The LT8609AEDDM-5#PBF delivers a fixed 5V output with guaranteed accuracy of 4.97V to 5.03V (±0.6%) at 100mA load and 25°C. Over the full –40°C to 125°C junction temperature range and 6V–40V input, output line regulation is ±0.02%/V, resulting in total variation within ±7.5% relative to nominal - the threshold used by the PG pin for power-good assertion. This ensures reliable downstream sequencing in automotive ECUs.

How does the LT8609AEDDM-5#PBF achieve ultralow quiescent current, and what is its typical value?

The LT8609AEDDM-5#PBF achieves 2.5µA typical quiescent current using Burst Mode operation: it delivers discrete energy packets to the output capacitor, then shuts down all switching and control circuitry during sleep intervals. At 12VIN → 5VOUT with no load, it draws just 2.5µA - verified per datasheet Figure G12. This enables multi-year battery life in always-on vehicle modules like toll tags or tire pressure sensors, where the LT8609AEDDM-5#PBF serves as the primary regulator.

Can the LT8609AEDDM-5#PBF be synchronized to an external clock, and what are the valid voltage levels?

Yes, the LT8609AEDDM-5#PBF supports external synchronization via its SYNC pin. Valid logic levels are: low (≤0.9V) for Burst Mode, high (≥2.7V, with INTVCC ≥3.5V) for pulse-skipping, and 3.2V–5.0V for spread spectrum modulation. When SYNC is tied to 3.3V, the part modulates switching frequency at 1–6kHz, reducing EMI peaks by >10dB - a key feature confirmed in LT8609A datasheet Section "Spread Spectrum Modulation Frequency" and essential for passing CISPR 25 testing in automotive designs using the LT8609AEDDM-5#PBF.

What is the thermal performance of the LT8609AEDDM-5#PBF in its DFN package, and how is heat dissipated?

The LT8609AEDDM-5#PBF in its 10-lead 3mm × 3mm side-wettable DFN has θJA = 45°C/W and θJC = 10°C/W. Heat is primarily dissipated through the exposed GND pad (Pin 11), which must be soldered to a large PCB copper area. Thermal imaging data (Figure G31) shows ≤60°C case rise at 3A load with 12VIN→5VOUT and 2MHz switching - confirming suitability for compact automotive modules. The LT8609AEDDM-5#PBF's low RDS(ON) (185mΩ top / 115mΩ bottom) minimizes conduction loss, further enhancing thermal efficiency.

Does the LT8609AEDDM-5#PBF require external feedback resistors, and how is output voltage set?

No, the LT8609AEDDM-5#PBF does not require external feedback resistors. It integrates an internal 8.95MΩ resistor divider that fixes the output to 5V, referenced to the VOUT pin. This eliminates BOM cost, layout sensitivity, and resistor tolerance errors associated with adjustable variants. The VOUT pin is the regulated output node - directly connected to the load and output capacitor - and is monitored by the PG comparator for ±7.5% fault detection. This architecture simplifies design and improves reliability in production systems using the LT8609AEDDM-5#PBF.