Diodes Incorporated AP1117DL-U

Overview

AP1117DL-U from Diodes Incorporated is a 1A low-dropout positive linear regulator in TO220-3L package, configurable as fixed 3.3V output or adjustable mode via external resistors. It delivers stable regulation with ≤1.4V dropout at full load, supports input voltages from 6.4V to 18V, and integrates thermal shutdown and current limiting. It is used in PC peripherals and VGA card power rails where compact, robust 3.3V supply is required.

For engineers reviewing the AP1117DL-U datasheet, AP1117DL-U pinout, AP1117DL-U application, or AP1117DL-U equivalent, this page provides verified technical context, real-world design meaning of specifications, validated pin functions, application-specific implementation guidance, and confirmed alternative parts for supply continuity and design flexibility.

Technical Context

The AP1117DL-U employs a PNP pass transistor architecture enabling low dropout operation while maintaining fast transient response to load steps. Its internal reference voltage is trimmed to 1.250V ±2.5% at 25°C, and output voltage accuracy is maintained across 0–125°C junction temperature range.

It features built-in thermal shutdown triggered at ~150°C junction temperature and foldback current limiting that reduces output current above 1.1A to prevent damage. Ripple rejection is 60–70dB at 180Hz with 25µF tantalum output capacitor, supporting noise-sensitive analog and digital logic supplies.

Key Specifications

Pinout & Package

AP1117DL-U uses the TO220-3L package with exposed thermal tab electrically connected to VOUT. The tab must be soldered to a large copper area for thermal performance and electrical connection.

Key Features

Applications

Equivalent & Alternatives

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

Compared with AP1117DL-U, AP1117K33G-13 offers superior thermal performance in SMT layouts, while LD1117S33TR trades off current capability and thermal margin for slightly lower dropout-neither is pin-compatible, requiring layout revision for substitution.

Availability

AP1117DL-U is available at Aetrix Electronics and suitable for PC peripheral power, VGA card core supply, and industrial HMI panel logic requiring stable component supply with long-term manufacturability and RoHS compliance.

Supply support for AP1117DL-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 industrial, computing, and consumer markets.

The AP1117 series is part of Diodes' precision linear regulator product line, designed specifically for cost-sensitive, high-reliability applications requiring robust thermal behavior and low-noise 3.3V/2.5V/1.8V logic supplies.

FAQ

What is the minimum input voltage required for AP1117DL-U to regulate 3.3V output at 1A?

The AP1117DL-U requires VIN ≥ VOUT + 1.4V to maintain regulation at full load. For a 3.3V output, minimum input is 4.7V. Below this, output voltage drops linearly with input; operation below 4.7V is not guaranteed to meet 3.3V ±1% specification.

Can AP1117DL-U be used in adjustable mode despite its 'DL' suffix indicating fixed 3.3V?

No. The 'DL' suffix denotes factory-trimmed fixed 3.3V output; the ADJ pin is internally connected to ground and not accessible for external feedback. To implement adjustable output, select AP1117EL-U (SOT223-3L, adjustable) or AP1117DL-U's adjustable counterpart AP1117D-U with external resistor network.

What is the recommended output capacitor for AP1117DL-U and why is ESR important?

A minimum 10µF tantalum or aluminum electrolytic capacitor with ESR between 0.15Ω and 20Ω is required at VOUT. ESR outside this range risks instability: too low causes oscillation; too high degrades transient response. Ceramic capacitors alone are insufficient unless paralleled with ≥0.5Ω damping resistor.

Does AP1117DL-U require a heatsink for 1A continuous operation at 25°C ambient?

With θ_JA = 78°C/W and 1A load at 12V input (8.7W dissipation), junction temperature rise is ~678°C-far exceeding 125°C limit. A heatsink reducing θ_JA to ≤14°C/W or PCB copper area ≥10 cm² with thermal vias is mandatory. Derating to ≤600mA is required without heatsinking.