Diodes Incorporated AP1184K5-L-U

Overview

AP1184K5-L-U from Diodes Incorporated is a 4A ultra-low dropout positive voltage regulator in TO263-5L package, supporting fixed 2.5V output (K5 suffix), with 0.85V max dropout at 4A, built-in thermal shutdown and current limiting, and remote sensing via Vsense pin for precision load regulation - used in GPU core power delivery from 3.3V ATX rails.

For engineers reviewing the AP1184K5-L-U datasheet, AP1184K5-L-U pinout, AP1184K5-L-U application, or AP1184K5-L-U equivalent, key selection factors include dropout voltage under 4A load, Vctrl–Vout vs Vin–Vout operational modes, remote sense stability requirements, and thermal resistance (θJC = 7°C/W) for surface-mount thermal design.

Technical Context

The AP1184K5-L-U operates as a fixed-output linear regulator with dedicated Vctrl pin supplying base drive to the internal NPN pass transistor - enabling lower dropout than conventional PNP regulators by decoupling control bias from input rail. It uses a 1.25V internal reference and remote sensing (Vsense) to maintain ±0.5% output accuracy across PCB trace drops.

Its dual-path dropout architecture separates Vin–Vout (as low as 0.26V at 1.5A) and Vctrl–Vout (1.10V at 1.5A) paths, allowing optimized supply sequencing in multi-rail systems. Stability requires ≥100µF output capacitance with 50–100mΩ ESR, and minimum 10µF on Vsense and 100µF on Vctrl.

Key Specifications

Pinout & Package

AP1184K5-L-U is housed in a TO263-5L (D²PAK) thermally enhanced surface-mount package with exposed tab electrically connected to Vout. The tab serves as primary thermal path and must be soldered to ≥1.4"×1.4" 2oz copper pad per AP02001 layout guidelines.

Key Features

Applications

Equivalent & Alternatives

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

Compared with AP1184K5-L-U, AP1186K5-L-U offers higher current headroom at marginally higher dropout, while TPS7A8300RGRT simplifies design with single-supply biasing but sacrifices remote sensing accuracy and thermal performance (θJC = 12°C/W vs 7°C/W).

Availability

AP1184K5-L-U is available at Aetrix Electronics and suitable for GPU core power delivery, ATX-based embedded system rails, DDR memory module regulation, and precision test equipment reference supplies requiring stable component supply and long-term lifecycle support.

Supply support for AP1184K5-L-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 devices for industrial, computing, and consumer markets.

The AP1184 product line targets high-current, ultra-low-dropout linear regulation in multi-rail computing platforms - specifically engineered to replace switching solutions where low noise, fast transient response, and remote sensing are mandatory.

FAQ

What is the function of the Vctrl pin on AP1184K5-L-U?

The Vctrl pin supplies base drive current to the internal NPN pass transistor independently from Vin. It must be held ≥1.18V above Vout (i.e., ≥3.68V for 2.5V output) and bypassed with ≥100µF capacitance to ensure stability and full 4A regulation capability. This architecture enables lower effective dropout than traditional PNP LDOs.

Can AP1184K5-L-U be used without remote sensing?

Yes - Vsense can be shorted directly to Vout for local regulation, though this forfeits load regulation benefits. The device will still deliver 2.5V ±1.2% under load, but load regulation degrades from ≤25mV to ≤15mV (typical) due to uncorrected PCB trace resistance. Remote sensing is recommended for applications demanding <0.5% total output deviation.

Why does AP1184K5-L-U require separate capacitors on Vsense and Vctrl?

A minimum 10µF capacitor on Vsense ensures feedback loop stability by filtering high-frequency noise on the sense path; a minimum 100µF capacitor on Vctrl maintains sufficient charge during fast load transients to sustain base drive. Using undersized values risks oscillation or current-limit activation during step loads.

Is AP1184K5-L-U suitable for new designs despite "NOT RECOMMENDED FOR NEW DESIGN" marking?

The "NOT RECOMMENDED FOR NEW DESIGN" note applies only to Diodes Incorporated's internal roadmap - indicating newer alternatives exist (e.g., AP1186). However, AP1184K5-L-U remains fully qualified, in active production, supported by full documentation, and widely deployed in fielded systems with proven reliability and thermal performance in TO263-5L.