Diodes Incorporated AP1084K33L-U

Overview

AP1084K33L-U from Diodes Incorporated is a 5A low-dropout positive fixed-mode voltage regulator delivering a precise 3.3V output with ≤1.4V dropout at full load, thermal shutdown protection, and built-in current limiting. It uses the TO263-3L package with exposed thermal tab connected to VOUT, and is designed for high-speed bus termination, 3.3V logic supply, and VGA card power regulation.

For engineers reviewing the AP1084K33L-U datasheet, AP1084K33L-U pinout, AP1084K33L-U application, or AP1084K33L-U equivalent, key selection factors include guaranteed 3.3V ±1.5% output accuracy at 5A, fast transient response under 100µs load steps, 30mV typical load regulation, and compatibility with standard 10µF/0.15–20Ω ESR output capacitors.

Technical Context

The AP1084K33L-U implements a single-stage LDO architecture with internal 1.25V reference and precision error amplifier, enabling stable regulation across input voltages from 4.8V to 12V while maintaining ≤1.4V dropout at 5A. Its control loop is optimized for fast load-step response (≤50µs recovery) and high PSRR (>60dB at 1kHz).

Thermal protection activates at 150°C junction temperature, and the device features fixed 3.3V output mode-eliminating external resistor networks-while retaining the same pinout and stability requirements as the adjustable variant. The TO263-3L package provides θJC = 3.5°C/W to the thermal tab, enabling ≥15W continuous dissipation with appropriate heatsinking.

Key Specifications

Pinout & Package

AP1084K33L-U uses the TO263-3L (D²PAK) thermally enhanced surface-mount package with 3 terminals and an exposed metal tab electrically connected to VOUT for optimal heat transfer. The tab must be soldered to a large copper pour for thermal performance.

Key Features

Applications

Equivalent & Alternatives

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

Compared with AP1084T33L-U, the K-suffix TO263-3L offers superior thermal performance for high-ambient industrial environments; compared with TLV1117-33CDCYR, AP1084K33L-U delivers 6.25× higher current and integrated protection-making it the sole viable choice for 5A fixed 3.3V regulation.

Availability

AP1084K33L-U is available at Aetrix Electronics and suitable for high-current 3.3V logic supply, VGA card power delivery, and industrial I/O module design requiring stable component supply and long-term manufacturing continuity.

Supply support for AP1084K33L-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 high-reliability power management, signal integrity, and protection solutions for industrial, computing, and consumer markets.

The AP1084 series belongs to Diodes' high-current LDO portfolio, engineered specifically for demanding 5A applications such as bus termination, graphics card power, and high-density embedded systems where thermal robustness and transient performance are critical.

FAQ

What is the minimum input voltage required for AP1084K33L-U to regulate at 5A?

The AP1084K33L-U requires VIN ≥ VOUT + 1.4V = 4.7V to maintain regulation at full 5A load. At lower input voltages, the device enters dropout mode and output voltage drops linearly with input-verified per Electrical Characteristics table (ΔVo = 1.3–1.4V at Io = 5.0A). Operation below 4.7V is permissible only for reduced-load conditions.

Can AP1084K33L-U be used without an output capacitor?

No. A minimum 10µF output capacitor with ESR between 0.15Ω and 20Ω is mandatory for stability and transient response, as confirmed in the Pin Description and Stability sections. Omitting it causes oscillation, excessive overshoot/undershoot during load steps, and potential damage due to uncontrolled voltage excursions.

Is the thermal tab of AP1084K33L-U electrically connected, and how should it be handled?

Yes-the TO263-3L thermal tab is internally connected to the VOUT pin. It must be soldered to a dedicated PCB copper pour tied to the 3.3V output net. This provides both thermal conduction path (θJC = 3.5°C/W) and electrical continuity; floating or grounding the tab will cause malfunction or destruction.

Does AP1084K33L-U support remote sensing for improved load regulation?

No. As a 3-terminal LDO, AP1084K33L-U lacks separate sense pins. Load regulation error arises from IR drop along PCB traces between VOUT pin and load; best practice is to minimize this path length and use wide copper pours. Remote sensing requires 4-terminal regulators like LT308x or TPS7A8x families.