STMicroelectronics LD1585CV33

Overview

LD1585CV33 from STMicroelectronics is a 3.3 V fixed-output, 5 A low-dropout linear voltage regulator in TO-220 package, featuring 1.2 V typical dropout at full load, ±1 % output tolerance at 25 °C, and fast transient response optimized for low-voltage systems such as SCSI-2 active termination and embedded power rails.

For engineers reviewing the LD1585CV33 datasheet, LD1585CV33 pinout, LD1585CV33 application, or LD1585CV33 equivalent, key selection criteria include guaranteed 5 A output current, thermal shutdown and internal current limiting, minimum 10 µF output capacitance for stability, and operation across 0 °C to 125 °C junction temperature range.

Technical Context

The LD1585CV33 uses an NPN pass transistor architecture-unlike PNP-based regulators-so quiescent current flows into the load, improving efficiency. Its reference voltage is trimmed on-chip to achieve ±1 % accuracy at 25 °C and ±2 % over full temperature range.

It delivers fast line and load transient response (e.g., <10 µs recovery under 0.1–5 A step load) due to high-gain error amplifier and optimized compensation. Dropout voltage remains ≤1.4 V at 5 A and decreases with lower load currents, enabling operation with minimal input–output differential.

Key Specifications

Pinout & Package

Supplied in TO-220 package with exposed metal tab (pin 2) for thermal and electrical connection to ground or heatsink. Pin 1 is Input, Pin 2 is Ground/Tab, Pin 3 is Output.

Key Features

Applications

Equivalent & Alternatives

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

Compared with LM350K and LT1529CT-3.3, the LD1585CV33 uniquely combines 5 A output, TO-220 thermal robustness, and ±1 % fixed 3.3 V accuracy-making it optimal for high-current industrial and computing power rails where precision and thermal margin are critical.

Availability

LD1585CV33 is available at Aetrix Electronics and suitable for industrial PLCs, test equipment power modules, embedded CPU core supplies, and SCSI-2 termination circuits requiring stable component supply and long-lifecycle support.

Supply support for LD1585CV33 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, designing and manufacturing analog, MCU, power, and sensor solutions for industrial, automotive, and consumer markets.

The LD1585C series was developed specifically for high-current, low-dropout linear regulation in space-constrained industrial and computing systems where fast transient response and thermal reliability are essential.

FAQ

What is the minimum input voltage required for LD1585CV33 to regulate at 3.3 V?

The minimum input voltage is determined by dropout: at 5 A load, maximum dropout is 1.4 V, so VI(min) = 3.3 V + 1.4 V = 4.7 V. At lighter loads, dropout decreases-e.g., ~0.8 V at 1 A-allowing operation down to ~4.1 V. Input must also exceed 2.75 V per datasheet line regulation test condition.

Can LD1585CV33 be used without an output capacitor?

No. A minimum 10 µF tantalum or ceramic capacitor is required at the output for stability and transient response. Omitting it risks oscillation, overshoot, or thermal shutdown during load steps. The capacitor must have low ESR (<1 Ω) and be placed close to the output pin.

Is the metal tab electrically isolated in the TO-220 package?

No. The metal tab (Pin 2) is internally connected to ground. It must be electrically tied to the PCB ground plane and thermally attached to a heatsink. Insulating hardware (e.g., mica washer + nylon screw) is required if mounting to a non-grounded heatsink.

Does LD1585CV33 support parallel operation for higher current?

No. The LD1585CV33 lacks current-sharing capability or master–slave control. Parallel connection without external ballasting resistors causes current imbalance and potential thermal runaway. For >5 A, use a single higher-rated regulator or switch-mode solution.