Diodes Incorporated AZ1085S-3.3TRE1

Overview

AZ1085S-3.3TRE1 from BCD Semiconductor Manufacturing Limited is a fixed-output 3.3V, 3A low-dropout linear regulator in TO-263-3 package with 1.3V typical dropout at full load, on-chip thermal shutdown, and ±1% output voltage accuracy over temperature and load. It delivers stable microprocessor supply rail for motherboards and telecom equipment requiring high-current, low-noise DC regulation.

For engineers reviewing the AZ1085S-3.3TRE1 datasheet, AZ1085S-3.3TRE1 pinout, AZ1085S-3.3TRE1 application, or AZ1085S-3.3TRE1 equivalent, key selection criteria include dropout voltage at 3A, thermal resistance (θJC = 4.15°C/W), load regulation (≤15 mV), and compatibility with standard PCB heatsinking for TO-263-3.

Technical Context

The AZ1085S-3.3TRE1 integrates a bandgap reference, current-limit circuit (4.5A), and thermal protection to maintain safe operation under overload or high ambient conditions. Its fixed 3.3V output eliminates external resistor networks, simplifying layout versus adjustable variants.

Designed for post-regulation after switching supplies, it operates across 4.8V–8V input range with 0–125°C junction temperature support and achieves 72dB ripple rejection at 120Hz with 25µF output capacitance.

Key Specifications

Pinout & Package

Package: TO-263-3 (D²PAK), surface-mount, thermally enhanced with exposed tab connected to OUTPUT pin for direct PCB heatsinking.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar 3.3V, 3A LDO applications.

Compared with LM1085IT-3.3/NOPB, AZ1085S-3.3TRE1 offers 0.2V lower dropout and 0.85°C/W better θJC-enabling 12% higher continuous power in TO-263-3 layouts. Versus TLV1117-33CDCYR, it delivers 3.75× more current in identical thermal envelope but requires different PCB land pattern.

Availability

AZ1085S-3.3TRE1 is available at Aetrix Electronics and suitable for motherboard power supplies, telecom line cards, set-top box modules, and DVD-video player designs requiring stable component supply with RoHS-compliant, lead-free packaging.

Supply support for AZ1085S-3.3TRE1 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 IC foundry specializing in high-voltage, high-current power management devices for industrial and consumer markets.

The AZ1085 series targets cost-sensitive, high-reliability linear regulation in computing, telecom, and consumer electronics-emphasizing thermal robustness, dropout efficiency, and drop-in compatibility with legacy TO-220/TO-263 footprints.

FAQ

What is the minimum input voltage required for stable 3.3V output at 3A?

The AZ1085S-3.3TRE1 requires ≥4.8V input to maintain regulation at 3A due to its 1.5V maximum dropout voltage. At 25°C, 4.6V input may sustain output briefly, but derating to 4.8V ensures reliable operation across 0–125°C junction range and accounts for trace resistance and input capacitor ESR.

Can this device be used without an output capacitor?

No. The AZ1085S-3.3TRE1 requires ≥22µF ceramic output capacitance with ≤10mΩ ESR for stability. Omitting it causes oscillation and thermal runaway under load. The datasheet specifies 22µF minimum, and values up to 100µF improve transient response without compromising phase margin.

How does the ADJ/GND pin function in the fixed-output version?

In AZ1085S-3.3TRE1, the ADJ/GND pin is internally connected to the feedback node and must be tied directly to system ground. It is not adjustable-external resistors are omitted per the fixed-output design. Any impedance between this pin and ground degrades load regulation and thermal performance.

Is thermal pad soldering mandatory for TO-263-3 package?

Yes. The exposed tab (Pin 2, OUTPUT) serves as the primary thermal path. IPC-7351B-compliant solder stencil and ≥70% copper fill beneath the pad are required to achieve the specified θJC = 4.15°C/W. Un-soldered or poorly wetted tabs increase junction temperature by >25°C at 3A, triggering premature thermal shutdown.