Analog Devices Inc. LT1585ACT-1.5#PBF

Overview

LT1585ACT-1.5#PBF from Analog Devices (formerly Linear Technology) is a fixed-output, low-dropout linear regulator delivering 5A at 1.5V with guaranteed dropout voltage ≤1.4V at full load, fast transient response optimized for Intel GTL+ bus termination, and integrated thermal limiting. It operates from 3V to 7V input, supports battery-powered logic supplies, and is housed in a TO-220 package with output-connected tab.

For engineers reviewing the LT1585ACT-1.5#PBF datasheet, LT1585ACT-1.5#PBF pinout, LT1585ACT-1.5#PBF application, or LT1585ACT-1.5#PBF equivalent, key selection criteria include guaranteed 5A output current, ±1% initial output voltage accuracy, 0.05% typical load regulation, 60–72dB ripple rejection, and thermal shutdown protection for microprocessor VTT rail design.

Technical Context

The LT1585ACT-1.5#PBF implements a monolithic 3-terminal LDO architecture with trimmed current limit (5.0–6.0A), on-chip thermal limiting (150°C junction cutoff), and frequency compensation enabling stable operation with low-ESR capacitors ≥22µF tantalum or ≥100µF aluminum electrolytic. Its control section and power transistor have separate thermal resistance specs (0.7°C/W and 3.0°C/W junction-to-case).

Unlike legacy regulators, it achieves fast transient response by minimizing output capacitance dependency-critical for nanosecond-scale load steps in GTL+ systems-while maintaining stability across temperature (–40°C to 125°C operating range) and input voltage (3V–7V). Dropout voltage remains ≤1.4V up to 5A, enabling efficient 3.3V-to-1.5V conversion.

Key Specifications

Pinout & Package

LT1585ACT-1.5#PBF uses a 3-pin TO-220 (T package) with output-connected metal tab for enhanced thermal dissipation. The tab is electrically tied to VOUT, requiring electrical isolation when mounted to heatsinks.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar low-dropout, high-current, fixed-output regulator applications.

Compared with LT1585CT-1.5#PBF, the LT1585ACT-1.5#PBF provides +0.4A guaranteed output and tighter current-limit consistency; versus LT1580CS8-2.5#PBF, it offers pin-compatible 1.5V fixed output in through-hole TO-220 but lacks adjustable functionality and ultra-low dropout.

Availability

LT1585ACT-1.5#PBF is available at Aetrix Electronics and suitable for Intel GTL+ bus termination, low-voltage microprocessor core supplies, and battery-powered logic systems requiring stable component supply and long-term industrial availability.

Supply support for LT1585ACT-1.5#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 and maintains its precision analog and power management portfolio, known for high-reliability linear regulators and data converters used in aerospace, industrial, and communications infrastructure.

The LT1585 family was designed specifically for high-current, low-noise, fast-transient VTT and logic supply applications in microprocessor-based systems - emphasizing GTL+ compliance, thermal robustness, and simplified layout with minimal external components.

FAQ

What is the maximum input voltage rating for the LT1585ACT-1.5#PBF?

The LT1585ACT-1.5#PBF has an absolute maximum input voltage of 7V. Operation above this level risks permanent damage. For reliable continuous operation, the recommended maximum input is 3.465V when powering a 3.3V ±5% source into 1.5V output at 5A - ensuring thermal limits remain within specification under worst-case ambient conditions.

Does the LT1585ACT-1.5#PBF require an output capacitor, and what type is recommended?

Yes, the LT1585ACT-1.5#PBF requires an output capacitor for stability. Linear Technology specifies ≥22µF solid tantalum or ≥100µF aluminum electrolytic as minimum values. Low-ESR capacitors (<1Ω) are strongly preferred - ceramic/tantalum combinations are ideal for GTL+ applications due to superior high-frequency transient response and reduced voltage droop during nanosecond load steps.

Is the metal tab on the LT1585ACT-1.5#PBF electrically connected, and how should it be mounted?

Yes, the metal tab on the LT1585ACT-1.5#PBF is internally connected to the VOUT pin. When mounting to a heatsink, electrical isolation is mandatory unless the heatsink is referenced to the 1.5V output rail. Use thermally conductive, electrically isolating pads or mica washers with thermal compound to maintain low thermal resistance while preventing short circuits.

How does the LT1585ACT-1.5#PBF compare to the LT1084 in terms of performance?

The LT1585ACT-1.5#PBF offers lower dropout voltage (≤1.4V vs. ~1.7V for LT1084 at 5A) and faster transient response due to improved internal compensation. It is pin-compatible with the LT1084 but has a lower 7V maximum input rating (vs. 30V for LT1084) and higher quiescent current (7–13mA vs. ~5mA), reflecting its optimization for low-voltage, high-speed logic rather than general-purpose use.

Can the LT1585ACT-1.5#PBF be used in automotive applications?

The LT1585ACT-1.5#PBF is rated for 0°C to 125°C control-section operation and 0°C to 150°C power-transistor operation, meeting extended temperature requirements for many under-hood automotive subsystems. However, it is not AEC-Q200 qualified; for automotive safety-critical designs, consult Analog Devices' automotive-grade alternatives or perform full qualification testing per ISO/TS 16949 requirements.