Diodes Incorporated AP1186T5-25G-U

Overview

AP1186T5-25G-U from Diodes Incorporated is a 1.5A ultra-low dropout positive voltage regulator in TO220-5L package, fixed at 2.5V output, with 0.38V max dropout at 1.5A load, ±2% output voltage tolerance, and integrated thermal shutdown and current limiting. It delivers stable power to graphics processor core supplies requiring 2.4–2.7V from 3.3V ATX rails.

For engineers reviewing the AP1186T5-25G-U datasheet, AP1186T5-25G-U pinout, AP1186T5-25G-U application, or AP1186T5-25G-U equivalent, key selection criteria include dropout voltage under full load, remote sensing capability via Vsense pin, control pin (Vctrl) biasing requirements, and thermal resistance (ΘJC = 2.5°C/W) for heatsink design in high-current linear regulation.

Technical Context

The AP1186T5-25G-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 dual-input flexibility enables operation from both 3.3V and 5V ATX rails.

True remote sensing is implemented via dedicated Vsense and Vout pins, enabling load-point voltage regulation by compensating for PCB trace IR drop. The device requires ≥100µF output capacitance and ≥10µF on Vsense for stability, with ripple rejection of 60–70dB at 120Hz.

Key Specifications

Pinout & Package

AP1186T5-25G-U is housed in a TO220-5L package with exposed tab electrically connected to Vout for thermal conduction. Pin 1 is Vin, Pin 2 is Vsense, Pin 3 is Adj (GND in fixed mode), Pin 4 is Vctrl, Pin 5 is Vout. The tab serves as secondary Vout connection and primary thermal path.

Key Features

Applications

Equivalent & Alternatives

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

Compared with AP1186K5-25G-U, the T5 variant offers easier manual prototyping and higher ΘJC-limited power handling; versus AP2202K-25, it delivers 5× higher current, 2× lower dropout, and true remote sensing-making it irreplaceable for GPU-core and high-accuracy analog biasing roles.

Availability

AP1186T5-25G-U is available at Aetrix Electronics and suitable for GPU power delivery, ATX motherboard auxiliary rails, FPGA I/O regulation, and medical sensor biasing requiring stable component supply with full traceability and long-term lifecycle support.

Supply support for AP1186T5-25G-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-reliability power management, signal integrity, and protection solutions for industrial, computing, and consumer markets.

The AP1186 series belongs to Diodes' high-current LDO portfolio, engineered specifically for graphics processor and high-performance logic applications demanding ultra-low dropout, remote sensing, and robust transient response from dual-rail ATX systems.

FAQ

Can AP1186T5-25G-U operate without a heatsink at 1.5A?

No. At 1.5A with 3.3V input and 2.5V output, power dissipation is ~1.28W in the pass element alone. With ΘJC = 2.5°C/W and typical ΘCA > 40°C/W, junction temperature exceeds 150°C without a heatsink. A minimum 15°C/W heatsink is required for continuous 1.5A operation at 25°C ambient.

What happens if the Vctrl pin is tied to Vin instead of a higher voltage rail?

Vctrl must exceed Vout by ≥2V to fully saturate the internal NPN pass transistor. If tied to Vin (e.g., 3.3V), Vctrl–Vout = 0.8V, causing incomplete turn-on, increased dropout (>1V), thermal runaway, and potential current-limit activation. Always use a separate ≥4.5V source (e.g., 5V rail) for Vctrl.

Is the Vsense pin mandatory for stable operation?

Yes. The Vsense pin must be connected directly to the Vout net (or to the load point for remote sensing). Leaving it floating causes regulation failure and oscillation. A minimum 10µF capacitor from Vsense to GND is required for loop stability, independent of the main output capacitor.

Does AP1186T5-25G-U support adjustable output configurations?

No. The "T5-25G-U" suffix denotes fixed 2.5V output in TO220-5L package. Adjustable versions use "-ADJ" suffix (e.g., AP1186T5-ADJG-U) and require external R1/R2 resistors between Adj, Vsense, and Vout to set output voltage from 1.25V to 15.5V.