Diodes Incorporated AP1084K50L-U

Overview

AP1084K50L-U from Diodes Incorporated is a 5.0A low-dropout positive fixed-mode voltage regulator in TO263-3L package, delivering tightly regulated 5.0V output with ≤1.4V dropout at full load, ±1% load regulation (40–50mV), and built-in thermal shutdown. It serves as a primary power supply for high-current 3.3V/5V logic rails, VGA card power stages, and bus termination circuits requiring stable low-noise DC.

For engineers reviewing the AP1084K50L-U datasheet, AP1084K50L-U pinout, AP1084K50L-U application, or AP1084K50L-U equivalent, key selection considerations include dropout voltage under 5A load, thermal resistance (θJC = 3.5°C/W), fixed 5.0V output tolerance (±1.5% at 10mA), minimum 10µF output capacitance requirement, and TO263-3L thermal tab grounding configuration.

Technical Context

The AP1084K50L-U implements a standard bandgap reference (1.25V nominal) with error amplifier and PNP pass transistor topology, enabling fixed-output operation without external resistors. Its internal current limiting (5.1A typical) and thermal shutdown (150°C trip) operate independently of external components.

Designed for high-current, low-input-headroom applications, it maintains regulation with VIN ≥ VOUT + 1.4V across 0–5A load range and supports fast transient response via optimized internal compensation - validated by ≤50mV output deviation during 0→5A load steps with 10µF tantalum output capacitor.

Key Specifications

Pinout & Package

AP1084K50L-U uses the TO263-3L (D²PAK) thermally enhanced surface-mount package with exposed metal tab electrically connected to VOUT. The tab must be soldered to a large copper pour for thermal conduction and electrical connection to the output net.

Key Features

Applications

Equivalent & Alternatives

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

Compared with AP1084T50L-U, the K50L-U offers 23% lower junction-to-ambient thermal resistance in SMT layout; versus LD1085V50, it provides tighter thermal protection and better transient response at the cost of narrower input voltage range.

Availability

AP1084K50L-U is available at Aetrix Electronics and suitable for VGA graphics power delivery, PCIe auxiliary rail generation, industrial bus termination, and legacy peripheral interface supply requiring stable component supply and long-term manufacturability.

Supply support for AP1084K50L-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 AP1084 series belongs to Diodes' high-current LDO regulator product line, engineered specifically for low-voltage, high-current IC supply applications including graphics subsystems, bus termination, and logic rail regulation where thermal robustness and transient immunity are critical.

FAQ

What is the minimum output capacitance required for stability?

The AP1084K50L-U requires a minimum 10µF aluminum or tantalum output capacitor with ESR between 0.15Ω and 20Ω, placed within 5mm of the VOUT pin. Ceramic capacitors alone are insufficient due to ultra-low ESR causing phase margin loss; a hybrid approach (e.g., 10µF tantalum + 100nF ceramic) is recommended for optimal transient response and stability.

Can AP1084K50L-U be used in adjustable mode?

No - the 'K50' suffix denotes fixed 5.0V output configuration. Internally, the ADJ pin is connected to GND; external resistor dividers cannot reconfigure the output voltage. For adjustable operation, select AP1084KADJL-U (TO263-3L, adjustable version) and follow the V_OUT = 1.25V × (1 + R2/R1) + I_ADJ×R2 formula with R1 = 121Ω minimum.

How is thermal performance affected by PCB layout?

Thermal resistance (θ_JA) drops from 60°C/W (datasheet FR-4 reference) to ≤45°C/W with ≥4cm² 2oz copper pour connected to the VOUT tab. Vias under the tab (≥6×0.3mm diameter) to inner-layer ground planes further reduce θ_JA. Poor layout - such as narrow traces or isolated tab - can raise junction temperature by >40°C at 5A, triggering thermal shutdown.

Is AP1084K50L-U suitable for automotive applications?

No - AP1084K50L-U is not AEC-Q100 qualified and operates only from 0°C to 125°C junction temperature. Its thermal shutdown threshold (150°C) lacks automotive-grade hysteresis, and the device has no specified PPAP documentation or extended temperature validation. For automotive use, consider Diodes' AEC-Q100 qualified AP7361 series or similar qualified LDOs.