Diodes Incorporated AP1084D33L-U

Overview

AP1084D33L-U from Diodes Incorporated is a 5A low-dropout linear regulator in TO252-3L package, delivering fixed 3.3V output with ≤1.4V dropout at full load, ±1% load regulation (26–33 mV), and 1.25V internal reference voltage. It supports high-speed bus termination and low-current 3.3V logic supply in VGA cards and embedded power rails.

For engineers reviewing the AP1084D33L-U datasheet, AP1084D33L-U pinout, AP1084D33L-U application, or AP1084D33L-U equivalent, key selection factors include dropout voltage under 5A load, thermal shutdown at 150°C, TO252-3L thermal resistance (θJA = 73°C/W), output stability with ≥10µF capacitor (ESR 0.15–20Ω), and fixed-mode GND-connected ADJ pin configuration.

Technical Context

The AP1084D33L-U operates as a fixed-output LDO with internal 1.25V reference and precision bandgap-controlled error amplifier. Its dropout voltage remains ≤1.4V across 0–5A load at junction temperatures up to 125°C, enabling stable 3.3V regulation from input supplies as low as 4.8V.

It integrates current limiting (5.1A typical), thermal shutdown (150°C trip), and fast transient response optimized for load steps from 0–5A. The device requires no external feedback resistors in fixed mode-pin 1 (Adj/GND) is internally tied to ground, simplifying PCB layout versus adjustable variants.

Key Specifications

Pinout & Package

AP1084D33L-U uses the TO252-3L (DPAK) surface-mount package with exposed thermal tab electrically connected to VOUT. The tab must be soldered to a large copper pour for thermal management and electrical connection to the output net.

Key Features

Applications

Equivalent & Alternatives

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

Compared with AP1084K33L-13, the AP1084D33L-U trades 13°C/W higher θJA for 30% smaller PCB area; versus TLV1117-33CDCY, it delivers 5× output current with integrated fault protection-making it the sole viable choice for high-current 3.3V LDO requirements.

Availability

AP1084D33L-U is available at Aetrix Electronics and suitable for high-speed bus termination, VGA card power supply, and embedded logic rail applications requiring stable component supply with lead-free compliance and TO252-3L thermal performance.

Supply support for AP1084D33L-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 in space-constrained applications-designed specifically for 3.3V/5A logic rails where switching noise must be avoided and thermal efficiency is secondary to simplicity and reliability.

FAQ

Is AP1084D33L-U pin-compatible with adjustable AP1084 variants?

No. In fixed-mode variants like AP1084D33L-U, Pin 1 (Adj/GND) is internally grounded and must connect directly to system ground-no external resistor divider is used or supported. Attempting to apply external resistors will disrupt regulation and may cause instability or overvoltage.

What is the minimum input voltage required for stable 3.3V output at 5A?

The minimum input voltage is 4.7V, derived from the 1.4V maximum dropout specification (3.3V + 1.4V = 4.7V). Operation below this voltage results in unregulated output; datasheet testing confirms regulation is maintained down to 4.8V at 25°C with proper thermal design.

Can AP1084D33L-U replace AP1084T33L-U in a TO220-3L design?

Yes, electrically-but mechanical redesign is required. Both deliver identical 3.3V/5A performance, but TO252-3L (D) has different pad layout, thermal tab connection, and mounting method than TO220-3L (T). PCB footprint, thermal copper, and assembly process must be updated per Diodes' AP02001 layout guidelines.

Does AP1084D33L-U require an input capacitor?

Yes. A minimum 10µF aluminum or tantalum capacitor (with ESR ≤20Ω) must be placed within 5mm of Pin 3 (VIN) to prevent input voltage sag during 5A load transients. Without it, line regulation degrades and the device may drop out momentarily during fast load steps.