Diodes Incorporated AP1086T33L-U

Overview

AP1086T33L-U from Diodes Incorporated is a 1.5A low dropout (LDO) positive fixed-mode voltage regulator delivering a stable 3.3V output. It features ≤1.4V dropout at full load, supports 4.8–12V input range, and is housed in a TO220-3L package with thermal shutdown and current limiting. It is designed for high-speed bus termination and low-current 3.3V logic supply in VGA cards and embedded systems.

For engineers reviewing the AP1086T33L-U datasheet, AP1086T33L-U pinout, AP1086T33L-U application, or AP1086T33L-U equivalent, key selection factors include dropout voltage at 1.5A load, output voltage tolerance (±2%), thermal resistance (θ_JA = 86°C/W), minimum required output capacitance (10µF), and fixed-output configuration eliminating external resistors.

Technical Context

The AP1086T33L-U operates as a three-terminal fixed-output LDO regulator with internal reference (1.25V) and error amplifier driving a PNP pass transistor. Its architecture enables fast transient response due to optimized internal compensation and minimal external component count-only input and output capacitors are required.

It guarantees regulation with VIN ≥ VOUT + 1.4V across 0–125°C junction temperature, incorporates built-in thermal shutdown (trip at 150°C), and provides current limiting at ≥1.6A. Load regulation is specified at ±33mV over 0–1.5A output current at 5V input.

Key Specifications

Pinout & Package

AP1086T33L-U uses the TO220-3L package: thermally enhanced through-hole plastic package with exposed tab electrically connected to VOUT. Mounting requires isolation from chassis ground unless VOUT is referenced to system ground.

Key Features

Applications

Equivalent & Alternatives

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

Compared with LM1117MPX-3.3/NOPB and TLV1117-33CDR, AP1086T33L-U delivers 50% higher output current in a thermally superior TO220 package, enabling single-regulator solutions for demanding 3.3V domains without parallel devices or oversized heatsinks.

Availability

AP1086T33L-U is available at Aetrix Electronics and suitable for PCI Express termination, VGA graphics card power, and industrial PLC I/O modules requiring stable component supply across extended temperature ranges and multi-year production cycles.

Supply support for AP1086T33L-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, headquartered in Plano, Texas, with design and manufacturing operations across Asia and the Americas.

The AP1086 series belongs to Diodes' high-current LDO regulator product line, engineered specifically for stable, low-noise, high-transient-performance power delivery in computing, graphics, and industrial control applications.

FAQ

What is the minimum input voltage required for AP1086T33L-U to regulate at full 1.5A load?

The device requires VIN ≥ VOUT + 1.4V to maintain regulation at full load. For its 3.3V output, minimum input is 4.7V. Operation below this threshold causes dropout-output voltage drops linearly with input, losing regulation. Input must remain ≥4.7V under worst-case load and temperature conditions.

Can AP1086T33L-U be used without an output capacitor?

No. A minimum 10µF aluminum electrolytic or tantalum capacitor is mandatory between VOUT and GND for stability and transient response. Omitting it risks oscillation, overshoot, or thermal runaway. Ceramic capacitors alone are insufficient due to ESR requirements; if used, add 1Ω series resistor to emulate required ESR.

Is the tab on AP1086T33L-U electrically isolated?

No-the metal tab is internally connected to Pin 2 (VOUT). When mounting to a heatsink, electrical isolation (e.g., mica washer + shoulder washer) is required unless the heatsink is referenced to the 3.3V rail. Failure to isolate may cause short circuits or ground loops in mixed-voltage systems.

How does thermal shutdown behave during sustained overload?

When junction temperature exceeds ~150°C, the internal thermal shutdown circuit disables the pass transistor, dropping output to near zero. After cooling below ~135°C hysteresis, regulation resumes automatically. This cycle prevents permanent damage but causes intermittent output-designers must size heatsinks to avoid repeated cycling under continuous overload.