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Home > Products > Integrated Circuits (ICs) > Power Management (PMIC) > Voltage Regulators - Linear, Low Drop Out (LDO) Regulators

STMicroelectronics LD1585CD2T18R

Name: LD1585CD2T18R
Brand: STMicroelectronics
SKU: LD1585CD2T18R
Price: 2.40 USD
Availability: InStock
Rating: 5 (2 reviews)

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Part No.:: LD1585CD2T18R

Manufacturer:: STMicroelectronics

Category:: Voltage Regulators - Linear, Low Drop Out (LDO) Regulators

Package:: TO-263-3, D2PAK (2 Leads + Tab), TO-263AB

Datasheet:: LD1585CD2T18R.pdf

Description:: IC REG LINEAR 1.8V 5A D2PAK

Quantity:: RFQ Add To RFQ list

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Inventory:911

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Product details

Overview

LD1585CD2T18R from STMicroelectronics is a 5 A low-dropout adjustable positive voltage regulator in TO-220 package, featuring 1.2 V typical dropout at full load, ±1 % output voltage tolerance at 25 °C, fast transient response, and internal thermal/overcurrent protection. It delivers stable regulation for high-current industrial power rails where input-to-output headroom is constrained.

For engineers reviewing the LD1585CD2T18R datasheet, LD1585CD2T18R pinout, LD1585CD2T18R application, or LD1585CD2T18R equivalent, key selection criteria include dropout voltage under 5 A load, adjust-pin current stability across temperature, minimum 10 µF output capacitance requirement, and compatibility with standard three-terminal adjustable regulator layouts.

Technical Context

The LD1585CD2T18R uses an NPN-based pass transistor architecture-unlike PNP regulators-so quiescent current flows into the load, improving efficiency. Its reference voltage is trimmed on-chip to ±1 % accuracy at 25 °C and maintains ±2 % over 0–125 °C junction range.

It achieves fast transient response via optimized internal compensation and requires only a 10 µF tantalum or ceramic output capacitor for stability. Dropout voltage remains ≤1.4 V at 5 A and decreases linearly with lower load currents, enabling operation down to ~2.75 V input for 1.8 V output configurations.

Key Specifications

Parameter	Value and Actual Design Meaning
Output current	Guaranteed 5 A continuous; enables single-regulator replacement of multiple lower-current LDOs in power distribution networks.
Dropout voltage	1.2 V typical / 1.4 V max at 5 A; allows operation with minimal VI–VO margin in 3.3 V or 2.5 V systems.
Output voltage tolerance	±1 % at 25 °C, ±2 % over full temperature range; reduces need for external trimming in precision analog supply rails.
Adjust pin current	50–100 µA at 10 mA load; stable over temperature and input voltage, simplifying resistor-divider design for setpoint accuracy.
Thermal resistance	R_thJC = 3 °C/W; supports high-power dissipation with basic heatsinking in TO-220 mounting.
Input voltage range	Up to 30 V DC; accommodates wide-input industrial supplies while maintaining regulation down to VI = VO + 1.4 V.

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 Adjust, Pin 2 is Output (tab), Pin 3 is Input.

Pin/Terminal	Circuit Role	Design Meaning
Pin 1 (ADJ)	Reference voltage feedback node	Connects to resistor divider between VO and GND; sets output as VO = 1.25 V × (1 + R2/R1).
Pin 2 (OUT / Tab)	Regulated output & thermal path	Electrically connected to output; must be isolated from chassis unless referenced to system ground.
Pin 3 (IN)	Unregulated input supply	Accepts up to 30 V DC; requires local 1 µF ceramic bypass near pin per transient immunity guidelines.

Key Features

Feature	Design Value
NPN pass transistor topology	Quiescent current delivered to load-not wasted-improving efficiency by ~5–10 % vs PNP equivalents at light loads.
On-chip voltage reference trimming	Enables ±1 % initial output accuracy without external calibration, reducing BOM count in cost-sensitive designs.
Internally limited short-circuit current	5.5–7 A peak during fault; provides self-protection without external current-sense circuitry.
Stable with 10 µF output capacitance	Eliminates need for large electrolytic capacitors; compatible with low-ESR tantalum and ceramic types.

Applications

Industrial PLC I/O Power

SCSI-2 Active Termination

Use Scenario: Regulating 1.8 V or 2.5 V from 5 V or 12 V bus for digital I/O modules in programmable logic controllers.

IC Role / Device Role / Timing Role: Primary post-regulator delivering clean, high-current bias to FPGA I/O banks and level-shifting buffers.

Use Value: 1.2 V dropout enables reliable 1.8 V output from 5 V rail even under 5 A transient load steps, minimizing brownout risk.

Use Scenario: Providing precisely regulated 2.85 V termination voltage for SCSI-2 differential bus lines.

IC Role / Device Role / Timing Role: Fixed-voltage termination regulator referenced to internal 1.25 V bandgap.

Use Value: ±1 % tolerance ensures impedance matching within spec; fast transient response suppresses termination noise during bus arbitration.

High-Current FPGA Core Supply

Test Equipment Bias Rails

Use Scenario: Generating 1.2 V or 1.5 V core voltage for mid-range FPGAs requiring >3 A steady-state current.

IC Role / Device Role / Timing Role: Low-noise, high-current analog supply rail decoupled from digital switching noise.

Use Value: 0.003 % RMS output noise and 75 dB SVR at 120 Hz reject ripple from upstream SMPS stages.

Use Scenario: Powering precision DACs, ADC references, and op-amp signal chains in automated test equipment.

IC Role / Device Role / Timing Role: Stable, low-drift analog supply with tight thermal coefficient (0.5 % long-term stability at 125 °C).

Use Value: ±2 % output tolerance over 0–125 °C eliminates recalibration drift in field-deployed instruments.

Equivalent & Alternatives

The following parts are listed as comparable options for similar adjustable high-current LDO regulator applications.

Alternative Part	Technical Difference	Application Difference	Selection Advice
LM338K STEEL	3 A rated, 2 V typical dropout, ±2 % output tolerance, TO-3 package	Limited to 3 A; higher dropout restricts use in <3.3 V input systems	Select when lower cost and legacy footprint compatibility outweigh current and dropout requirements.
LT1083CP	7.5 A rated, 1.5 V dropout, ±1 % tolerance, TO-220 package, higher quiescent current	Higher max current and tighter thermal specs; requires ≥22 µF output cap for stability	Choose for >5 A loads or extended ambient temperature operation beyond 125 °C junction limit.

Compared with LM338K STEEL and LT1083CP, the LD1585CD2T18R offers optimal balance of 5 A capability, sub-1.4 V dropout, and TO-220 thermal performance-making it preferred for space-constrained industrial power rails needing both current and efficiency.

Availability

LD1585CD2T18R is available at Aetrix Electronics and suitable for industrial PLC I/O power, SCSI-2 termination, and FPGA core supply applications requiring stable component supply and long-lifecycle support.

Supply support for LD1585CD2T18R 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, designing and manufacturing microcontrollers, power management ICs, sensors, and analog components for industrial, automotive, and consumer markets.

The LD1585C series targets high-current, low-dropout linear regulation in industrial control and computing infrastructure-emphasizing thermal robustness, transient immunity, and compatibility with legacy three-terminal regulator footprints.

FAQ

What is the minimum output capacitance required for stability?

The LD1585CD2T18R is stable with a minimum 10 µF tantalum or ceramic output capacitor. Lower ESR values (e.g., <1 Ω) are acceptable, but aluminum electrolytics with high ESR may cause oscillation. A 1 µF ceramic bypass at the input pin is also recommended for transient immunity.

Can this regulator be used in parallel for higher current?

No-parallel operation is not supported. The LD1585CD2T18R lacks current-sharing features such as remote sensing or master-slave control. Attempting parallel connection risks thermal runaway due to mismatched dropout voltages and reference tolerances.

Is the exposed tab electrically connected to any internal node?

Yes-the TO-220 metal tab is internally connected to the output (Pin 2). It must be electrically isolated from the heatsink or chassis unless the output node is referenced to system ground. Use insulating shoulder washers and mica pads if mounting to grounded metal surfaces.

Does the device require a minimum load current to maintain regulation?

Yes-minimum load current is 3–10 mA depending on input voltage. Below this threshold, output voltage may rise above regulation due to adjust-pin current flowing through the feedback divider. A 1–2 kΩ bleed resistor from output to ground ensures compliance across all operating conditions.

LD1585CD2T18R Specifications

Product attributes: Attribute value

Manufacturer:: STMicroelectronics

Series:: -

Package/Case:: TO-263-3, D2PAK (2 Leads + Tab), TO-263AB

Packaging:: Tape & Reel (TR)

Product Status:: Obsolete

Output Configuration:: Positive

Output Type:: Fixed

Number of Regulators:: 1

Voltage - Input (Max):: 30V

Voltage - Output (Min/Fixed):: 1.8V

Voltage - Output (Max):: -

Voltage Dropout (Max):: 1.4V @ 5A

Current - Output:: 5A

Current - Quiescent (Iq):: 10 mA

Current - Supply (Max):: -

PSRR:: 75dB (120Hz)

Control Features:: -

Protection Features:: Over Current, Over Temperature

Operating Temperature:: 0°C ~ 125°C

Grade:: -

Qualification:: -

Mounting Type:: Surface Mount

Supplier Device Package:: D2PAK

LD1585CD2T18R FAQ

1.How can I place an order for LD1585CD2T18R through Aetrix?

Please submit a Request for Quotation (RFQ) for LD1585CD2T18R on Aetrix. Our sales agent will provide a competitive quotation and guide you through the order confirmation once you accept the terms.

2.Are the price and stock information for LD1585CD2T18R reliable?

The price and inventory of LD1585CD2T18R are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LD1585CD2T18R is usually 5 days.

3.What payment methods are accepted for LD1585CD2T18R?

We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LD1585CD2T18R transactions.

Note: Certain payment methods may incur a processing fee.

4.How is shipping managed for LD1585CD2T18R?

LD1585CD2T18R orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.

Once your LD1585CD2T18R order is processed, you will receive an email with the shipment details and tracking number.

Note: Tracking information may take up to 24 hours to appear. Express delivery typically takes 3–5 business days.

5.How can I obtain technical support or documentation for LD1585CD2T18R?

For technical support, including LD1585CD2T18R datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LD1585CD2T18R requirements.

6.How does Aetrix verify that LD1585CD2T18R is sourced from the original manufacturer or authorized distributors?

All LD1585CD2T18R products on Aetrix are procured from qualified distributors and authorized channels. Our dedicated quality assurance team conducts strict verification, including traceability checks and, if necessary, third-party testing. This ensures that LD1585CD2T18R meets industry standards.

7.What is the process for return or replacement of LD1585CD2T18R?

All LD1585CD2T18R units undergo pre-shipment inspection (PSI). If there is an issue with LD1585CD2T18R, returns or replacements are accepted under the following conditions:

1.Quantity discrepancies, incorrect items, or visible external defects (such as breakage or corrosion), acknowledged by Aetrix.

2.The issue is reported within 90 days of delivery.

3.The LD1585CD2T18R part is unused and in its original packaging.

Return procedure for LD1585CD2T18R:

1.Submit a request within 90 days.

2.Obtain a Return Material Authorization (RMA) from Aetrix.

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