Diodes Incorporated AZ1085S-1.8TRE1

Overview

AZ1085S-1.8TRE1 from BCD Semiconductor Manufacturing Limited is a fixed-output 1.8 V, 3 A low dropout linear regulator in TO-263-3 package with 1.3 V typical dropout at full load, on-chip thermal shutdown, and ±1% output voltage accuracy over temperature and load. It delivers stable microprocessor core power in motherboards and telecom equipment where input-to-output differential is constrained.

For engineers reviewing the AZ1085S-1.8TRE1 datasheet, AZ1085S-1.8TRE1 pinout, AZ1085S-1.8TRE1 application, or AZ1085S-1.8TRE1 equivalent, key selection criteria include dropout voltage at 3 A, thermal protection behavior, load regulation (≤15 mV), line regulation (≤6 mV), and compatibility with standard PCB layout practices for TO-263-3 thermal pads.

Technical Context

The AZ1085S-1.8TRE1 integrates a bandgap reference, current-limit circuit (4.5 A), and thermal shutdown into a monolithic silicon regulator. Its internal architecture uses a PNP pass transistor to achieve low dropout while maintaining stability with ≥10 µF ceramic or tantalum output capacitance.

It operates across 0–125 °C junction temperature and supports input voltages up to 12 V. The fixed 1.8 V output eliminates external resistor networks, reducing component count and improving accuracy versus adjustable variants that depend on ADJ pin current drift (55–120 µA).

Key Specifications

Pinout & Package

Package: TO-263-3 (D²PAK), surface-mount, thermally enhanced with exposed tab connected to OUTPUT pin for efficient heat transfer to PCB copper pour.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar fixed-output LDO applications.

Compared with LD1085V18TR and TLV1117-18CDCYR, the AZ1085S-1.8TRE1 uniquely combines 3 A capability, TO-263-3 thermal efficiency, and 72 dB ripple rejection - making it the only drop-in solution for high-density, noise-sensitive 1.8 V core rails requiring no derating below 125 °C.

Availability

AZ1085S-1.8TRE1 is available at Aetrix Electronics and suitable for motherboard power rails, telecom line cards, and DVD player logic supplies requiring stable component supply, RoHS compliance, and long-lifecycle support.

Supply support for AZ1085S-1.8TRE1 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

BCD Semiconductor Manufacturing Limited is a Shanghai-based analog and power IC designer specializing in high-reliability, cost-optimized regulators, MOSFETs, and LED drivers for industrial and consumer markets.

The AZ1085 series targets high-current linear regulation in space-constrained, thermally demanding applications - emphasizing dropout minimization, integrated protection, and package flexibility across TO-220, TO-263, and TO-252 variants.

FAQ

What is the minimum input voltage required for stable 1.8 V output at 3 A?

The AZ1085S-1.8TRE1 requires a minimum input voltage of 3.1 V (1.8 V + 1.3 V typical dropout) to maintain regulation at full 3 A load. At light loads (<100 mA), input can drop to 2.5 V due to lower dropout, but design margin should retain ≥3.3 V input for reliability across temperature and process variation.

Can this device replace an adjustable AZ1085 variant in an existing design?

No - the AZ1085S-1.8TRE1 is a fixed-output variant with internal resistor network; it lacks the ADJ pin functionality of adjustable versions. Swapping requires removing external R1/R2 feedback components and verifying that the 1.8 V output meets downstream IC requirements without adjustment headroom.

Is a heatsink required for continuous 3 A operation at 70 °C ambient?

With proper PCB thermal design - including ≥4 cm² 2-oz copper pour connected to the exposed OUTPUT tab via ≥6 thermal vias - no external heatsink is needed. Thermal resistance from junction to ambient (θJA) drops to ~45 °C/W in such layouts, keeping TJ <125 °C at 3 A with 1.3 V dropout (3.9 W dissipation).

Does the AZ1085S-1.8TRE1 support reverse-voltage or reverse-current protection?

No - the device lacks built-in reverse-voltage or reverse-current blocking. If input may fall below output (e.g., during hot-swap or backup battery switchover), an external Schottky diode between INPUT and OUTPUT is required to prevent backfeed and potential damage to upstream sources.