Diodes Incorporated AP1184T5-50L-U

Overview

AP1184T5-50L-U from Diodes Incorporated is a 4A ultra-low dropout positive fixed-mode linear regulator in TO220-5L package, delivering 5.0V ±2% output with 0.85V max dropout at 4A load, thermal shutdown, and remote sensing via Vsense pin. It targets GPU core power delivery from 3.3V/5V ATX rails in graphics card designs requiring 2.4–2.7V–compatible regulation.

For engineers reviewing the AP1184T5-50L-U datasheet, AP1184T5-50L-U pinout, AP1184T5-50L-U application, or AP1184T5-50L-U equivalent, key selection criteria include dropout voltage under full load, remote sensing capability for load-point accuracy, thermal resistance (θJA = 31°C/W), control pin (Vctrl) biasing requirements, and fixed-output stability with ≥100µF output capacitance.

Technical Context

The AP1184T5-50L-U uses an NPN-based architecture with externally biased Vctrl pin to eliminate base-current losses typical of PNP LDOs, enabling ultra-low dropout while maintaining high efficiency at low VIN–VOUT differentials. Its separate Vsense and Vout pins enable true Kelvin sensing for <15mV load regulation error across 0–4A.

It integrates current limiting (4.2A min), thermal shutdown (135°C trip), and ripple rejection of 60–70dB at 120Hz. The device requires dual decoupling: ≥100µF on Vctrl-to-GND and ≥100µF on Vout-to-GND for stability under fast GPU load transients (300–500ns step response).

Key Specifications

Pinout & Package

AP1184T5-50L-U is housed in a TO220-5L package with exposed tab electrically connected to Vout. The tab serves as primary thermal path and must be mounted to heatsink or large copper area. Pin 1 = Vout (tab), Pin 2 = Vsense, Pin 3 = Adj (GND in fixed mode), Pin 4 = Vctrl, Pin 5 = Vin.

Key Features

Applications

Equivalent & Alternatives

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

Compared with AP1184K5-50L-U and TPS7A8300RGRT, the AP1184T5-50L-U uniquely combines TO220-5L mechanical robustness, remote sensing, and Vctrl-biased NPN architecture-enabling lowest possible dropout while maintaining load-point accuracy in high-current graphics and FPGA applications.

Availability

AP1184T5-50L-U is available at Aetrix Electronics and suitable for GPU power delivery, ATX auxiliary rail conditioning, and industrial FPGA I/O bank regulation requiring stable component supply and long-term industrial lifecycle support.

Supply support for AP1184T5-50L-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 computing, industrial, and consumer markets.

The AP1184 product line delivers ultra-low dropout linear regulators optimized for graphics processor and high-performance logic power domains where efficiency, transient response, and remote sensing are critical.

FAQ

What is the minimum required capacitor on the Vctrl pin?

A minimum 100µF aluminum electrolytic capacitor must be placed between Vctrl and ground to ensure loop stability and sufficient charge delivery during fast load transients. This capacitor supports internal bias generation and pass transistor base drive, preventing oscillation or dropout under 4A step loads.

Can the AP1184T5-50L-U operate without connecting the Vsense pin?

Yes - in fixed-output mode, Vsense must be connected directly to Vout (not left floating) to maintain regulation accuracy. Leaving Vsense unconnected causes output voltage error and instability. Remote sensing is optional but recommended for applications with >50mΩ PCB trace resistance between regulator and load.

Why does the Vctrl pin require a higher voltage than Vin?

Vctrl supplies the internal control circuitry and base drive for the NPN pass transistor. It must exceed Vout by ≥1V to ensure sufficient gate/base drive margin across temperature and process variation. Unlike standard LDOs, Vctrl operates independently of Vin, allowing optimization of control rail (e.g., 5V) even when Vin is only 5.85V.

Is AP1184T5-50L-U suitable for new designs despite "NOT RECOMMENDED FOR NEW DESIGN" in the datasheet?

No - Diodes Incorporated explicitly marks AP1184 as "NOT RECOMMENDED FOR NEW DESIGN" due to obsolescence planning. While fully functional and supported for existing production, Aetrix recommends evaluating pin-compatible alternatives like AP1184K5-50L-U (TO263-5L) or next-generation regulators for new schematics to ensure long-term supply continuity.