STMicroelectronics KD1084ADT33R

Overview

KD1084ADT33R from STMicroelectronics is a fixed-output 3.3 V, ±1 % tolerance, 5 A low-dropout linear voltage regulator in DPAK package, designed for high-current post-regulation in industrial power supplies and embedded systems where input-to-output differential is constrained. It delivers guaranteed 5 A output with 1.3 V typical dropout at full load, 60–72 dB supply voltage rejection at 120 Hz, and operates across –40 °C to +125 °C junction temperature.

For engineers reviewing the KD1084ADT33R datasheet, KD1084ADT33R pinout, KD1084ADT33R application, or KD1084ADT33R equivalent, key selection criteria include dropout voltage at 5 A, output tolerance over temperature, thermal resistance (R_thJA = 100 °C/W in DPAK), and compatibility with minimal 10 µF tantalum output capacitance for stability.

Technical Context

The KD1084ADT33R uses an NPN-based pass transistor architecture-unlike PNP regulators-so quiescent current flows into the load rather than being wasted, improving efficiency under light loads. Internal trimming achieves ±1 % output accuracy at 25 °C and ±2 % over full temperature range.

It integrates thermal shutdown and current limiting, with internal power dissipation limits enforced via junction temperature sensing. Dropout voltage remains stable down to 1.3 V at 5 A and decreases linearly with reduced load, enabling operation with as little as 4.9 V input for 3.3 V output.

Key Specifications

Pinout & Package

Supplied in surface-mount DPAK (TO-252) package with exposed thermal pad for enhanced heat dissipation. Pin 1 = Input, Pin 2 = Ground, Pin 3 = Output.

Key Features

Applications

Equivalent & Alternatives

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

Compared with LD1085V33 and TPS75733KTTT, KD1084ADT33R uniquely combines ±1 % accuracy, NPN efficiency advantage, DPAK surface-mount compatibility, and proven industrial temperature operation-making it optimal for space-constrained, high-reliability 5 A LDO applications where input headroom is limited.

Availability

KD1084ADT33R is available at Aetrix Electronics and suitable for industrial PLCs, telecom line cards, automotive body control modules, and medical imaging subsystems requiring stable component supply with guaranteed long-term manufacturability.

Supply support for KD1084ADT33R 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

STMicroelectronics is a global semiconductor leader headquartered in Geneva, Switzerland, specializing in power management, microcontrollers, sensors, and automotive ICs with vertical manufacturing capability and broad industrial qualification.

KD1084ADT33R belongs to ST's high-current linear regulator product line, engineered specifically for demanding post-regulation tasks in industrial automation, communications infrastructure, and automotive electronics where reliability, thermal robustness, and tight output tolerance are critical.

FAQ

What is the minimum input voltage required for KD1084ADT33R to maintain regulation at 5 A?

The minimum input voltage is 4.9 V, derived from the sum of nominal output (3.3 V) and maximum specified dropout (1.5 V). At 5 A load and 25 °C, typical dropout is 1.3 V, so 4.6 V suffices-but 4.9 V ensures margin across temperature and process variation per datasheet Table 5.

Can KD1084ADT33R be used with ceramic output capacitors instead of tantalum?

No-datasheet Figure 4 and Section 4 specify ≥10 µF tantalum (low ESR) for stability; ceramic capacitors' near-zero ESR can cause phase-margin loss and oscillation. If ceramics are mandatory, an external RC snubber (e.g., 1 Ω + 1 µF) in series with the output cap is required per ST AN2407 guidelines.

Does KD1084ADT33R include reverse polarity or reverse current protection?

No-KD1084ADT33R lacks integrated reverse-voltage or reverse-current blocking. If input can fall below output (e.g., during hot-swap or backup battery switchover), an external Schottky diode from IN to OUT is required to prevent backfeed and potential damage to the pass transistor.

How does the thermal shutdown behavior respond during sustained overload?

When junction temperature exceeds ~165 °C, internal thermal limit circuitry disables the pass transistor, dropping output to zero. After cooldown to ~145 °C, auto-restart occurs. This hiccup-mode protection prevents permanent damage but causes output interruption-designers must size input bulk capacitance to sustain downstream loads during brief shutdown intervals.