Diodes Incorporated AP1117K33L-U

Overview

AP1117K33L-U from Diodes Incorporated is a 1A low-dropout linear voltage regulator with fixed 3.3V output, TO263-3L surface-mount package, 1.4V maximum dropout at full load, built-in thermal shutdown and current limiting, designed for stable 3.3V logic supply in PC peripherals and VGA cards.

For engineers reviewing the AP1117K33L-U datasheet, AP1117K33L-U pinout, AP1117K33L-U application, or AP1117K33L-U equivalent, key selection considerations include dropout voltage under 1.4V at 1A, ±2% output accuracy over temperature, 70dB ripple rejection at 180Hz, and TO263-3L thermal resistance (θ_JC = 3.5°C/W) for high-power-density board designs.

Technical Context

The AP1117K33L-U integrates a precision bandgap reference, error amplifier, and PNP pass transistor in a fixed-output configuration. Its internal current limit and thermal shutdown circuitry activate at ≥1.1A and ≥150°C respectively, ensuring safe operation during overload or ambient overheating.

It delivers regulated 3.3V output across input voltages from 4.8V to 18V, with load regulation of ≤33mV (0–1A) and line regulation of ≤0.2% - enabling reliable performance in bus termination and low-noise digital supply rails where transient response and noise rejection are critical.

Key Specifications

Pinout & Package

AP1117K33L-U uses the TO263-3L (D²PAK) thermally enhanced surface-mount package with exposed metal tab electrically connected to VOUT for improved heat transfer and mechanical anchoring.

Key Features

Applications

Equivalent & Alternatives

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

Compared with TLV1117-33CDR and MIC29302WU-3.3, AP1117K33L-U balances proven 1A capability, industry-standard TO263 thermal performance, and minimal BOM count - making it optimal for cost-sensitive, thermally demanding 3.3V supply rails where simplicity and reliability are prioritized.

Availability

AP1117K33L-U is available at Aetrix Electronics and suitable for PC peripheral power, VGA card core supply, and industrial control I/O requiring stable component supply, long-term lifecycle support, and RoHS-compliant sourcing.

Supply support for AP1117K33L-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 board-level point-of-load conversion in PC, graphics, and embedded systems where fixed-output simplicity and ruggedness are essential.

FAQ

What is the minimum input voltage required for AP1117K33L-U to regulate 3.3V output?

The AP1117K33L-U requires VIN ≥ VOUT + 1.3V to maintain regulation, so minimum input is 4.6V. However, the datasheet specifies guaranteed operation starting at 4.8V under full 1A load and 125°C junction temperature - allowing margin for line drop and thermal derating in real-world layouts.

Can AP1117K33L-U be used with ceramic output capacitors?

Yes, but only with careful ESR consideration: the device requires 0.15–20Ω ESR for stability. Standard X7R/X5R ceramics typically have <10mΩ ESR and may cause oscillation. Use ceramic capacitors with added series resistance or select specialty high-ESR ceramics (e.g., Z5U with ~1Ω ESR) verified per Diodes Inc. AN-3001 guidelines.

How does thermal shutdown behave during continuous overload?

When junction temperature reaches ~150°C, the AP1117K33L-U disables its pass transistor and holds output at zero volts until die temperature falls by ~15°C, then resumes regulation. This hiccup-mode behavior prevents permanent damage but causes intermittent output - design must ensure heatsinking or current limiting avoids sustained entry into thermal shutdown.

Is AP1117K33L-U compatible with lead-free reflow profiles?

Yes - AP1117K33L-U is qualified for standard Pb-free reflow per JEDEC J-STD-020 Rev. E, with peak temperature up to 260°C for ≤30 seconds. Its TO263-3L package uses matte tin plating and green molding compound compliant with RoHS Directive 2002/95/EC and halogen-free requirements.