Diodes Incorporated AP1184T5-25L-U

Overview

AP1184T5-25L-U from Diodes Incorporated is a 4A ultra-low dropout positive voltage regulator in TO220-5L package, configured for fixed 2.5V output. It delivers 2.5V at up to 4A load with 0.85V maximum dropout (Vin–Vout) at full load, built-in thermal shutdown and current limiting, and remote sensing via Vsense pin-designed for GPU core power delivery from 3.3V ATX rails.

For engineers reviewing the AP1184T5-25L-U datasheet, AP1184T5-25L-U pinout, AP1184T5-25L-U application, or AP1184T5-25L-U equivalent, key selection criteria include dropout performance under 4A transient loads, remote-sense stability with ≥100µF output capacitance, thermal resistance (θJA = 31°C/W), and compatibility with dual-rail motherboard supplies (3.3V input + 5V Vctrl).

Technical Context

The AP1184T5-25L-U uses an NPN pass transistor architecture with externally supplied Vctrl pin (≥Vout+1V), enabling lower dropout than standard PNP LDOs while avoiding base-current losses. Its separate Vsense and Vout pins support true remote voltage regulation at the load point.

It operates with Vin ≥ 3.2V (for 2.5V output), requires ≥100µF output capacitor and ≥100µF Vctrl bypass capacitor, and integrates thermal shutdown triggered above 125°C junction temperature. Load regulation is specified at ≤25mV over 0–4A at 25°C.

Key Specifications

Pinout & Package

AP1184T5-25L-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 pour.

Key Features

Applications

Equivalent & Alternatives

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

Compared with AP1184K5-25L-U, the TO220-5L variant offers simpler mechanical mounting and higher single-point thermal dissipation; versus TPS7A8300RGRT, it trades off IQ and integration for 2× current capacity, remote sensing, and dual-rail robustness essential in desktop GPU power.

Availability

AP1184T5-25L-U is available at Aetrix Electronics and suitable for GPU power delivery, ATX motherboard auxiliary rails, industrial FPGA I/O regulation, and test equipment analog supplies requiring stable component supply with long-term lifecycle visibility.

Supply support for AP1184T5-25L-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 targets high-current, ultra-low-dropout regulation in cost-sensitive computing infrastructure-specifically engineered to replace switching regulators in GPU and chipset power stages where noise, layout complexity, and BOM count must be minimized.

FAQ

What is the minimum input voltage required for AP1184T5-25L-U to regulate 2.5V at 4A?

The absolute minimum input voltage is 3.35V, based on the 0.85V maximum dropout (Vin – Vout) specification at 4A load and 25°C. In practice, design margin requires Vin ≥ 3.5V to ensure regulation across temperature, line, and load variations-especially with 3.3V ATX rails that may sag under system load.

Can AP1184T5-25L-U operate without the Vctrl pin connected?

No. Vctrl must be supplied with a stable voltage ≥1V above Vout (i.e., ≥3.5V for 2.5V output). This pin powers the internal control circuitry and pass transistor base drive. Leaving Vctrl unconnected or below threshold disables regulation and may cause unpredictable output behavior or thermal runaway under load.

Is remote sensing mandatory, or can Vsense be tied directly to Vout?

Vsense may be tied to Vout for local regulation, but doing so forfeits remote sensing benefits. When tied together, load regulation degrades to ≤25mV (vs ≤10mV with proper remote sense), and PCB trace resistance introduces direct error into output voltage. For GPU or FPGA applications, remote connection to the load is strongly recommended.

Why does AP1184T5-25L-U require both Vin and Vctrl supplies?

The dual-supply architecture separates power path (Vin → Vout) from control bias (Vctrl → internal circuitry). This allows Vctrl to be derived from a cleaner, higher-voltage rail (e.g., 5V) independent of the noisy 3.3V input, improving PSRR by >10dB and enabling stable operation even when Vin sags near dropout-critical for transient-heavy GPU workloads.