Diodes Incorporated AP1186K5-50L-U

Overview

AP1186K5-50L-U from Diodes Incorporated is a 1.5A ultra-low dropout positive fixed-mode linear regulator in TO263-5L package, delivering a precise 5.0V output with ≤0.38V dropout at 1.5A load, built-in thermal shutdown and current limiting, and optimized for GPU core supply in ATX-based motherboards.

For engineers reviewing the AP1186K5-50L-U datasheet, AP1186K5-50L-U pinout, AP1186K5-50L-U application, or AP1186K5-50L-U equivalent, key selection criteria include dropout voltage under full load, remote sensing capability via Vsense pin, control pin (Vctrl) biasing requirements, thermal resistance (ΘJC = 2.5°C/W), and stability with ≥100µF output capacitance.

Technical Context

The AP1186K5-50L-U uses an NPN pass transistor architecture with externally biased Vctrl pin-separate from Vin-to achieve ultra-low dropout while avoiding base-current losses typical of PNP regulators. Its 5-pin topology enables true remote sensing via dedicated Vsense and Adj pins.

It operates in fixed-output mode (5.0V) with internal reference trimmed to 1.25V, supports fast transient response for GPU load steps (~300–500ns), and requires Vctrl ≥ Vin + 1V to maintain regulation. Stability relies on ≥100µF output capacitor with 50–100mΩ ESR.

Key Specifications

Pinout & Package

AP1186K5-50L-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 per Diodes Inc. 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 AP1186T5-50L-U, the K5 variant offers superior thermal performance in compact SMT layouts; versus TPS7A4700RGWR, it trades noise performance for architectural flexibility in multi-rail systems requiring remote sensing and separate control biasing.

Availability

AP1186K5-50L-U is available at Aetrix Electronics and suitable for GPU power delivery, ATX motherboard rail conversion, industrial FPGA I/O supply, and test equipment reference voltage generation requiring stable component supply with RoHS-compliant lead-free finish.

Supply support for AP1186K5-50L-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 high-efficiency power management, signal integrity, and protection solutions for computing, industrial, and consumer markets.

The AP1186 series belongs to Diodes' ultra-low dropout linear regulator product line, engineered specifically for high-current, low-voltage GPU and ASIC core supply applications where traditional PNP LDOs incur excessive power loss.

FAQ

What is the minimum input voltage required for AP1186K5-50L-U to regulate 5.0V at 1.5A?

The datasheet specifies a minimum input voltage of 5.5V for 5.0V output at 1.5A load, based on maximum dropout of 0.38V. Operation below 5.5V risks dropout and unregulated output. Input must also satisfy Vctrl ≥ Vin + 1V-so with Vin = 5.5V, Vctrl ≥ 6.5V is required.

Can AP1186K5-50L-U be used without remote sensing?

Yes. The Vsense pin may be shorted directly to Vout for local regulation, though this forfeits remote sensing benefits. In that configuration, load regulation degrades to ≤50mV over full load (vs. <10mV with remote sensing), and PCB trace resistance introduces additional output error.

Why does AP1186K5-50L-U require a separate Vctrl pin instead of using Vin for internal bias?

The Vctrl pin supplies base current to the NPN pass transistor independently of Vin, enabling ultra-low dropout by eliminating base-drive voltage overhead. Using Vin for bias would force Vin ≥ Vout + Vbe ≈ Vout + 0.7V-doubling effective dropout versus the 0.26V achieved with external Vctrl ≥ Vin + 1V.

Is AP1186K5-50L-U compatible with ceramic output capacitors?

No. The AP1186K5-50L-U requires aluminum electrolytic or tantalum capacitors with 50–100mΩ ESR for stability, as its compensation relies on ESR zero. Ceramic capacitors (ESR <10mΩ) cause phase-margin loss and potential oscillation unless an external RC network is added per Diodes Application Note AP02001.