Diodes Incorporated AP1184T5-15L-U

Overview

AP1184T5-15L-U from Diodes Incorporated is a 4A ultra-low dropout positive fixed-mode linear regulator with 1.5V output, TO220-5L package, 0.85V max dropout at 4A, thermal shutdown, and remote sensing via Vsense pin. It delivers stable 1.5V/4A supply for GPU core voltage regulation from 3.3V ATX rails in desktop motherboards.

For engineers reviewing the AP1184T5-15L-U datasheet, AP1184T5-15L-U pinout, AP1184T5-15L-U application, or AP1184T5-15L-U equivalent, key selection criteria include dropout voltage under 4A load, remote sensing capability for ±15mV load regulation, thermal resistance (θJA = 31°C/W), and fixed 1.5V output accuracy (±2% at 10mA).

Technical Context

The AP1184T5-15L-U uses an NPN pass transistor architecture with separate Vctrl and Vsense pins to achieve ultra-low dropout while avoiding base-current losses typical of PNP regulators. Its control loop maintains 1.25V reference between Adj and Vsense pins, enabling precise remote voltage sensing at the load.

It implements true remote sensing by comparing feedback at the Vsense pin-connected directly to the load-to the internal 1.25V reference, compensating for PCB trace IR drop. Thermal shutdown activates above 125°C junction temperature, and current limiting trips at 4.2A minimum.

Key Specifications

Pinout & Package

AP1184T5-15L-U is housed in a TO220-5L package with exposed tab electrically connected to Vout for thermal conduction and output return path. The tab must be mounted to heatsink or large copper pour.

Key Features

Applications

Equivalent & Alternatives

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

Compared with AP1184K5-15L-U, the T5 variant offers superior thermal performance in chassis-mounted systems via TO220 heatsinking, while LT1963AEST-1.5 lacks both the 4A rating and remote sensing-making AP1184T5-15L-U uniquely capable for high-current, precision GPU core regulation.

Availability

AP1184T5-15L-U is available at Aetrix Electronics and suitable for GPU core power supplies, ATX motherboard VRM stages, industrial FPGA I/O banks, and test equipment reference rails requiring stable component supply with full traceability and long-term lifecycle support.

Supply support for AP1184T5-15L-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-performance power management, signal integrity, and protection solutions for computing, industrial, and consumer markets.

The AP1184 product line targets high-current, ultra-low-dropout linear regulation for graphics and processor core supplies-designed specifically to replace switching regulators in noise-sensitive, space-constrained applications where efficiency and simplicity must coexist.

FAQ

What is the minimum input voltage required for AP1184T5-15L-U to regulate 1.5V at 4A?

The minimum input voltage is 2.35V, derived from the maximum dropout voltage of 0.85V at 4A load (1.5V + 0.85V). However, the datasheet specifies a minimum Vin of 2.2V for the 1.5V version-valid only if load current is reduced. At full 4A, Vin must remain ≥2.35V to maintain regulation and avoid thermal overload.

Can AP1184T5-15L-U operate without a heatsink?

No. With θJA = 31°C/W and 1.68W typical dissipation at 2A (3.3V→1.5V), junction temperature rises ~52°C above ambient. At 4A and 25°C ambient, power dissipation reaches ~3.36W, causing >100°C rise-exceeding the 125°C max junction limit. A heatsink or ≥3in² copper area is mandatory for continuous 4A operation.

Is the Vsense pin required for basic operation?

Yes, Vsense must be connected directly to the Vout pin for standard operation-even in fixed-mode variants. Leaving it unconnected degrades load regulation to ±100mV. For remote sensing, connect Vsense to the load point instead of Vout; this improves regulation accuracy to ±15mV by compensating for PCB trace resistance.

Why does AP1184T5-15L-U require a separate Vctrl supply?

Vctrl powers the internal control circuitry and base drive for the NPN pass transistor. It must be ≥1V above Vout (i.e., ≥2.5V) to ensure sufficient gate/base drive margin. This decouples control bias from the main Vin rail, enabling stable regulation even when Vin sags near dropout-critical for maintaining GPU supply during high-current transients.