Diodes Incorporated AP1084KL-U

Overview

AP1084KL-U from Diodes Incorporated is a 5A low-dropout positive voltage regulator in TO263-3L package, supporting both adjustable and fixed-output modes (1.5V/1.8V/2.5V/3.3V/5.0V). It delivers ≤1.4V dropout at full 5A load, features built-in thermal shutdown and current limiting, and is optimized for high-speed bus termination and low-current 3.3V logic supply in VGA cards and embedded power rails.

For engineers reviewing the AP1084KL-U datasheet, AP1084KL-U pinout, AP1084KL-U application, or AP1084KL-U equivalent, key selection criteria include dropout voltage under 5A load, output stability with 10µF ESR-constrained capacitor, thermal resistance (θJC = 3.5°C/W), and compatibility with fixed- or resistor-programmed output configurations.

Technical Context

The AP1084KL-U implements a three-terminal LDO architecture with internal 1.25V reference and adjustable feedback via external R1/R2 divider. Its control loop maintains regulation with only 1.4V VIN–VOUT differential at 5A, enabling efficient conversion from 4.7V–12V inputs to outputs as low as 1.25V.

It integrates overcurrent protection that limits output to ≥5.1A and thermal shutdown triggered at 150°C junction temperature. Stability requires ≥10µF output capacitance (ESR 0.15–20Ω), and minimum load current is 10mA - satisfied by standard 121Ω R1 in typical 3.3V designs.

Key Specifications

Pinout & Package

AP1084KL-U uses the TO263-3L surface-mount package with exposed thermal tab electrically connected to VOUT. The tab must be soldered to a large copper pour for thermal performance and electrical connection to output net.

Key Features

Applications

Equivalent & Alternatives

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

Compared with AP1084KL-U, AP1084K-33L-U removes design complexity for fixed 3.3V use but sacrifices programmability, while TLV1117LV33DCYR offers lower dropout at light loads but cannot sustain 5A continuously or match thermal performance in high-power applications.

Availability

AP1084KL-U is available at Aetrix Electronics and suitable for VGA graphics card power, high-speed bus termination, and industrial embedded logic rails requiring stable component supply with long lifecycle visibility and RoHS-compliant sourcing.

Supply support for AP1084KL-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 consumer markets.

The AP1084 belongs to Diodes' high-current LDO regulator product line, engineered specifically for demanding point-of-load applications in graphics, memory, and embedded systems where thermal robustness and transient performance are critical.

FAQ

What output voltages does AP1084KL-U support?

AP1084KL-U is an adjustable-mode variant - it does not have a factory-set output voltage. Using external resistors R1 and R2, it can be configured for any output between 1.25V and (VIN − 1.4V). Common configurations include 1.5V, 1.8V, 2.5V, 3.3V, and 5.0V, with typical 121Ω/200Ω dividers yielding accurate 3.3V outputs.

Can AP1084KL-U be used without external resistors?

No - AP1084KL-U requires external R1 and R2 resistors to set the output voltage in adjustable mode. Leaving the Adj pin open or shorting it to ground disables regulation. For resistorless operation, select a fixed-output variant like AP1084K-33L-U (3.3V) or AP1084K-25L-U (2.5V), which integrate the feedback network internally.

What is the minimum output capacitance required for stability?

AP1084KL-U requires a minimum 10µF aluminum or tantalum capacitor at the VOUT pin, with ESR between 0.15Ω and 20Ω. Ceramic capacitors alone are insufficient due to near-zero ESR; if used, they must be paralleled with a ≥0.15Ω damping resistor or a bulk electrolytic/tantalum capacitor to ensure phase margin and prevent oscillation.

How is thermal performance affected by PCB layout?

Thermal performance depends critically on soldering the TO263-3L thermal tab (connected to VOUT) to ≥4 cm² of 2oz copper on the PCB. Without adequate copper area, junction temperature rises rapidly - θJA degrades from 60°C/W (with recommended pad) to >100°C/W on minimal land patterns, risking thermal shutdown at <3A load.