Diodes Incorporated AP1186K5-25L-U

Overview

AP1186K5-25L-U from Diodes Incorporated is a 1.5A ultra-low dropout positive voltage regulator in TO263-5L package, fixed at 2.5V output, with 0.38V max dropout at 1.5A load, built-in thermal shutdown and current limiting, designed for GPU core supply in ATX-based graphics cards requiring stable 2.4–2.7V rails.

For engineers reviewing the AP1186K5-25L-U datasheet, AP1186K5-25L-U pinout, AP1186K5-25L-U application, or AP1186K5-25L-U equivalent, key selection criteria include dropout voltage under full load, remote sensing capability via Vsense pin, thermal resistance (ΘJC = 2.5°C/W), control pin (Vctrl) biasing requirements, and stability with ≥100µF aluminum electrolytic output capacitance.

Technical Context

The AP1186K5-25L-U uses an NPN pass transistor architecture with externally biased Vctrl pin-separate from Vin-to eliminate base-current-related inefficiency typical of PNP LDOs. Its 5-pin topology enables true remote sensing by decoupling Vsense from Vout, compensating for PCB trace IR drop.

It operates with Vctrl ≥ Vin + 1V (min), requires ≥100µF output capacitor for stability, and delivers tight initial accuracy (±2% over temperature) and fast transient response (<500ns load step recovery) critical for GPU core voltage regulation under dynamic switching loads.

Key Specifications

Pinout & Package

AP1186K5-25L-U is housed in a surface-mount TO263-5L (D²PAK) package with exposed tab electrically connected to Vout for thermal conduction. The tab must be soldered to ≥1.4"×1.4" copper area for optimal thermal performance 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 AP1186K5-25L-U, the TO220 variant offers identical electrical performance but different thermal mounting; the TPS7A4700 trades 1.5A capability and remote sensing for ultra-low noise and wide adjustability-making it unsuitable for GPU core supply but viable for low-current reference rails.

Availability

AP1186K5-25L-U is available at Aetrix Electronics and suitable for graphics card design, ATX motherboard development, industrial FPGA power management, and test equipment reference rail generation requiring stable component supply with RoHS-compliant lead-free finish.

Supply support for AP1186K5-25L-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 AP1186 product line delivers high-current, ultra-low-dropout LDOs with remote sensing and dual-rail biasing-designed specifically for GPU core and FPGA I/O supply in ATX-based platforms where efficiency, simplicity, and transient response outweigh switching complexity.

FAQ

What is the minimum required output capacitance for stable operation?

The AP1186K5-25L-U requires a minimum of 100µF aluminum electrolytic capacitor at the Vout pin to ensure loop stability and adequate transient response. This value assumes typical ESR of 50–100mΩ; lower-ESR ceramics may destabilize the regulator unless combined with sufficient bulk capacitance.

Can the Vsense pin be left unconnected in non-remote-sensing applications?

No. The Vsense pin must be connected directly to Vout in fixed-mode operation-even without remote sensing-because it forms the feedback path for the internal error amplifier. Leaving it floating will cause regulation failure or oscillation.

Why does Vctrl need to be higher than Vin, and what happens if it isn't?

Vctrl supplies base drive to the NPN pass transistor; if Vctrl ≤ Vin, the transistor cannot saturate, causing excessive dropout, thermal runaway, or complete loss of regulation. Minimum Vctrl = Vin + 1V ensures sufficient V_CE headroom for full conduction at 1.5A.

Is the AP1186K5-25L-U compatible with lead-free reflow profiles?

Yes. The AP1186K5-25L-U carries the "L" suffix indicating lead-free finish and RoHS compliance per EU Directive Annex Notes 5 and 7. It is qualified for standard Pb-free reflow profiles with peak temperatures up to 260°C, per J-STD-020.