Diodes Incorporated AP1084TG-U

Overview

AP1084TG-U from Diodes Incorporated is a 5A low-dropout positive voltage regulator available in fixed 3.3V output mode, housed in a TO220-3L package with thermal tab connected to VOUT. It delivers ≤1.4V dropout at full 5A load, supports input voltages from 4.8V to 12V, and features built-in thermal shutdown and current limiting. It is designed for high-speed bus termination and low-current 3.3V logic supply in VGA cards and embedded power rails.

For engineers reviewing the AP1084TG-U datasheet, AP1084TG-U pinout, AP1084TG-U application, or AP1084TG-U equivalent, key selection criteria include dropout voltage under 5A load, thermal resistance (θJA = 78°C/W), output stability with ≥10µF capacitor (ESR 0.15–20Ω), and fixed-mode operation without external resistors.

Technical Context

The AP1084TG-U operates as a three-terminal fixed-output LDO regulator with internal 1.25V reference and error amplifier driving a PNP pass transistor. Its feedback loop is internally configured for 3.3V output, eliminating external resistor networks required in adjustable variants.

It employs thermal foldback current limiting and junction temperature sensing to trigger shutdown at 150°C. Dropout behavior is characterized by a 1.3–1.4V VIN–VOUT differential at 5A, enabling stable 3.3V regulation from as low as 4.7V input while maintaining ±1% load regulation over 0–5A.

Key Specifications

Pinout & Package

AP1084TG-U uses the TO220-3L package with exposed thermal tab electrically connected to VOUT (Pin 2). The tab must be mounted to a heatsink or copper pour for thermal management. Package outline conforms to JEDEC TO-220AB standard with 3.55–4.85mm body height and 15.35mm length.

Key Features

Applications

Equivalent & Alternatives

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

Compared with AP1084TG-U, AP1084T33L-U offers identical performance with standard lead-free finish, while LM1084IT-3.3/NOPB trades halogen-free compliance and lower dropout for slightly better thermal resistance - making AP1084TG-U optimal for green-compliant, high-efficiency 3.3V rail designs.

Availability

AP1084TG-U is available at Aetrix Electronics and suitable for VGA graphics card power, PCI bus termination, and industrial embedded logic rails requiring stable component supply with halogen-free compliance and 5A continuous output capability.

Supply support for AP1084TG-U 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

Diodes Incorporated is a global manufacturer of discrete semiconductors and analog ICs, specializing in power management, signal integrity, and protection solutions for industrial, computing, and consumer markets.

The AP1084 product line targets high-current, low-noise linear regulation for legacy and modern bus architectures - emphasizing dropout efficiency, thermal robustness, and regulatory compliance in through-hole power delivery.

FAQ

What is the minimum input voltage required for AP1084TG-U to regulate 3.3V at 5A?

The AP1084TG-U requires VIN ≥ VOUT + 1.4V to maintain regulation at full load, so minimum input is 4.7V. At 4.8V input, it delivers full 5A with ≤1.4V dropout; operation below 4.7V risks dropout and unregulated output. Input must remain ≥4.8V across all operating temperatures and line conditions.

Can AP1084TG-U be used in adjustable mode?

No - AP1084TG-U is factory-configured for fixed 3.3V output. The "TG" suffix denotes TO220-3L package with Green compound and fixed 3.3V function. Adjustable versions use "-ADJ" suffix (e.g., AP1084TG-ADJ) and require external R1/R2 resistors; this part has internal feedback and no adjust pin functionality.

Is a heatsink mandatory for AP1084TG-U at 5A continuous load?

Yes - with θJA = 78°C/W and power dissipation up to 15W (e.g., 12V→3.3V @ 5A = 43.5W theoretical, but derated), a heatsink is essential. Without one, junction temperature exceeds 150°C within seconds. Use ≥10cm² copper pour or finned heatsink; thermal pad between tab and heatsink is required for reliable conduction.

Does AP1084TG-U support reverse-voltage protection?

No - AP1084TG-U lacks reverse-input or reverse-output protection. Applying reverse polarity to VIN or VOUT can damage the internal pass transistor and reference circuitry. External protection (e.g., series Schottky diode on VIN or back-to-back MOSFETs) must be added if system-level reverse-voltage exposure is possible.