Diodes Incorporated AP1117D25L-U

Overview

AP1117D25L-U from Diodes Incorporated is a 1A low-dropout linear voltage regulator with fixed 2.5V output, TO220-3L package, 1.4V max dropout at full load, ±2% output voltage accuracy, and integrated thermal shutdown. It delivers stable 2.5V power for FPGA I/O banks, DDR memory termination, and industrial sensor signal conditioning circuits requiring precise low-noise supply.

For engineers reviewing the AP1117D25L-U datasheet, AP1117D25L-U pinout, AP1117D25L-U application, or AP1117D25L-U equivalent, this page provides verified pin functions, real-world load transient response data, fixed-output design constraints, and validated alternatives for 2.5V LDO replacement in space-constrained industrial PCBs.

Technical Context

The AP1117D25L-U uses a PNP pass transistor architecture with internal bandgap reference (1.25V) and error amplifier to maintain regulation across 4.0–12V input range. Its fixed 2.5V output is achieved via internal resistor divider - no external feedback components required.

Thermal shutdown activates at 150°C junction temperature, and current limiting holds output at ~1.1A under short-circuit conditions. Ripple rejection is 60–70dB at 180Hz with 25µF tantalum output capacitor, supporting noise-sensitive analog front-ends.

Key Specifications

Pinout & Package

AP1117D25L-U uses TO220-3L package: thermally enhanced through-hole package with metal tab electrically connected to VOUT, enabling direct heatsink mounting and low thermal resistance (θ_JC = 3.5°C/W).

Key Features

Applications

Equivalent & Alternatives

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

Compared with TLV1117-25CDR and MCP1702T-2502E/MB, AP1117D25L-U uniquely supports 1A continuous output in TO220 package with 1.4V dropout and industrial temp range - making it the sole choice for high-current, thermally demanding 2.5V rails where SOT packages would exceed junction limits.

Availability

AP1117D25L-U is available at Aetrix Electronics and suitable for industrial sensor signal chains, FPGA I/O power rails, DDR memory termination networks, and embedded microcontroller analog peripheral supplies requiring stable component supply with full traceability and long-term lifecycle support.

Supply support for AP1117D25L-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 communications markets.

The AP1117 product line delivers cost-optimized, thermally robust LDO regulators targeting high-current, low-noise local regulation in space-constrained PCBs - specifically engineered for bus termination, logic supply, and mixed-signal subsystems.

FAQ

What is the maximum input voltage for AP1117D25L-U?

The absolute maximum DC input voltage is 18V per the datasheet's Absolute Maximum Ratings table. However, recommended operating input range is 4.0V to 12V for optimal thermal performance and regulation stability. Exceeding 12V increases power dissipation significantly - at 1A load and 18V input, power loss reaches 15.5W, requiring substantial heatsinking to stay below 150°C junction limit.

Can AP1117D25L-U be used in adjustable mode?

No. The "D25" suffix denotes fixed 2.5V output, and the Adj pin is internally connected to GND. Only AP1117 variants marked "ADJ" (e.g., AP1117DXXL-U with "XX" = "AD") support adjustable output via external resistor divider. Attempting to reconfigure AP1117D25L-U as adjustable will result in incorrect or unstable output voltage due to internal topology hardwiring.

Is a heatsink required for AP1117D25L-U at 1A load?

Yes, under continuous 1A load with >6V input differential. With θ_JA = 78°C/W and 1.4V dropout, power dissipation is 1.4W - causing ~109°C rise above ambient. At 25°C ambient, junction temperature reaches ~134°C, nearing thermal shutdown. A 10°C/W heatsink reduces θ_JA to ~20°C/W, limiting rise to ~28°C and keeping T_J safely below 125°C.

What output capacitor is required for stability?

A minimum 10µF tantalum or aluminum electrolytic capacitor with ESR between 0.15Ω and 20Ω must be placed directly at the VOUT pin. Ceramic capacitors alone are insufficient due to near-zero ESR causing phase-margin degradation. Diodes' datasheet Figure 1 shows C1 = 10µF (input) and C2 = 22µF (output) in typical 2.5V application - using 22µF improves transient response and noise filtering beyond minimum requirements.