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STMicroelectronics LD1585CD2M18R
- Part No.:
- LD1585CD2M18R
- Manufacturer:
- STMicroelectronics
- Package:
- TO-263-4, D2PAK (3 Leads + Tab), TO-263AA
- Datasheet:
-
LD1585CD2M18R.pdf
- Description:
- IC REG LINEAR 1.8V 5A D2PAK-3
- Quantity:
- Payment:
- Shipping:
Inventory:1,373
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Product details
Overview
LD1585CD2M18R 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, and fast transient response optimized for low-voltage systems such as SCSI-2 active termination and industrial power rails.
For engineers reviewing the LD1585CD2M18R datasheet, LD1585CD2M18R pinout, LD1585CD2M18R application, or LD1585CD2M18R equivalent, key selection criteria include guaranteed 5 A output current, internal thermal/power limiting, minimum 10 µF output capacitance for stability, and compatibility with standard three-terminal adjustable regulator circuits.
Technical Context
The LD1585CD2M18R employs 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 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 low-output-impedance design. Dropout voltage remains ≤1.4 V at 5 A and decreases linearly with lower output current, enabling operation with minimal input–output differential.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Output current | Guaranteed 5 A continuous; supports high-power analog/digital rails without external parallel devices. |
| Dropout voltage | 1.2 V typical / 1.4 V max at 5 A; enables 3.3 V or 2.85 V outputs from 5 V or 4.2 V supplies. |
| Output voltage tolerance | ±1 % at 25 °C; ensures precise regulation for sensitive logic or ADC reference supplies. |
| Adjust pin current | 50–100 µA typical; allows high-value resistor dividers (e.g., 10 kΩ/1.2 kΩ) with minimal error contribution. |
| Thermal resistance | RthJC = 3 °C/W; supports >4 W dissipation with basic heatsinking before thermal shutdown. |
| Input voltage range | Up to 30 V DC; accommodates unregulated 24 V industrial inputs with sufficient headroom for ripple. |
| Noise performance | 0.003 % RMS output noise (10 Hz–10 kHz); suitable for low-noise analog subsystems without added filtering. |
Pinout & Package
Supplied in TO-220 package with exposed metal tab (pin 2) for thermal conduction and electrical connection to output. Standard three-terminal adjustable configuration: Pin 1 = Adjust, Pin 2 = Output, Pin 3 = Input.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| Pin 1 (ADJ) | Reference voltage feedback node | Connects to resistor divider; sets output via VOUT = VREF(1 + R2/R1), where VREF = 1.25 V. |
| Pin 2 (OUT) | Regulated output terminal | Delivers up to 5 A; electrically tied to metal tab for low-impedance thermal path and EMI reduction. |
| Pin 3 (IN) | Unregulated input supply | Accepts up to 30 V; requires local 10 µF ceramic/tantalum bypass capacitor for stability. |
Key Features
| Feature | Design Value |
|---|---|
| NPN pass transistor topology | Directs quiescent current into load-no wasted bias current-improving efficiency by ~5–10 % vs PNP regulators at light loads. |
| On-chip trimming | Enables ±1 % initial output voltage accuracy without external calibration, reducing BOM count and test time. |
| Internal thermal & current limiting | Automatically reduces output current during overload or overheating-no external protection circuitry required. |
| Fast transient response | Stabilizes within <10 µs after 0.1–5 A load steps-critical for FPGA core rails and real-time control loops. |
| Low external component count | Only two resistors (for adjustment) and one 10 µF output capacitor needed-reduces PCB area and cost vs switching alternatives. |
Applications
| SCSI-2 Active Termination | Industrial 3.3 V Power Rail |
|---|---|
Use Scenario: Provides stable 2.85 V termination voltage for SCSI-2 bus signaling under varying cable lengths and device counts. IC Role / Device Role / Timing Role: Adjustable LDO regulator delivering precision termination voltage independent of host supply variations. Use Value: Maintains signal integrity across hot-plug events and load transients with <10 µs recovery-prevents bus lockup or data corruption. | Use Scenario: Supplies 3.3 V to PLC I/O modules operating in 0–70 °C ambient with 24 V DC field supply. IC Role / Device Role / Timing Role: Primary linear regulator converting unregulated 24 V to clean 3.3 V for microcontroller and sensor interfaces. Use Value: Delivers 5 A with ±2 % tolerance over full temperature range and rejects 75 dB of 120 Hz ripple-eliminates need for post-regulation filtering. |
| Test Equipment Power Supply | Embedded Audio DAC Reference |
Use Scenario: Powers analog front-end stages in portable multimeters requiring ultra-low noise and zero-load stability. IC Role / Device Role / Timing Role: Low-noise adjustable LDO supplying bias to op-amps and ADC drivers. Use Value: 0.003 % RMS output noise and 0.5 % long-term stability over 1000 hours ensure measurement repeatability and calibration retention. | Use Scenario: Generates clean 2.5 V reference for stereo audio DACs in networked audio endpoints. IC Role / Device Role / Timing Role: Precision voltage reference source decoupled from noisy digital supply domains. Use Value: ±1 % initial tolerance and 0.02 %/W thermal regulation minimize THD+N drift across playback volume and temperature changes. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar adjustable LDO regulator applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| LM338K STEEL | Higher dropout (2 V min), ±2 % tolerance, no internal thermal limit-requires external protection. | Less suitable for low-input-headroom designs; limited to 5 A only with aggressive heatsinking. | Prefer when legacy LM338 footprint compatibility is mandatory and input headroom ≥2.5 V is available. |
| LT1083CP | Lower quiescent current (0.05 mA), but slower transient response (>50 µs) and higher noise (20 µVRMS). | Better for battery-powered standby rails; less ideal for dynamic FPGA or DSP core supplies. | Choose when ultra-low IQ dominates over transient speed and noise is secondary to power budget. |
Compared with LM338K STEEL and LT1083CP, the LD1585CD2M18R offers superior dropout performance and integrated protection-making it optimal for space-constrained industrial systems where input voltage margin is tight and reliability is critical.
Availability
LD1585CD2M18R is available at Aetrix Electronics and suitable for SCSI-2 termination, industrial 3.3 V power rails, and embedded audio reference supplies requiring stable component supply across extended temperature ranges and multi-year production cycles.
Supply support for LD1585CD2M18R 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 analog, MCU, power, and sensor solutions for industrial, automotive, and consumer markets.
The LD1585C series belongs to ST's high-current linear regulator product line, engineered specifically for applications demanding low dropout, fast transient immunity, and robust thermal behavior in compact TO-220 packages.
FAQ
What is the minimum output capacitor required for stability?
The LD1585CD2M18R requires a minimum 10 µF output capacitor-tantalum or ceramic-with ESR between 0.1 Ω and 1 Ω. Lower ESR values may cause oscillation; adding a 1 µF ceramic in parallel improves high-frequency PSRR without compromising stability.
Can this regulator be used in parallel for higher current?
No-LD1585CD2M18R lacks built-in current-sharing capability. Parallel operation risks thermal runaway due to mismatched dropout voltages and gain. For >5 A, use a single higher-current regulator or switch to a controller-based solution with external MOSFETs.
Is the metal tab electrically connected to any pin?
Yes-the TO-220 metal tab is internally connected to Pin 2 (Output). It must be electrically isolated from chassis ground unless the output rail is referenced to system ground. Use insulating shoulder washers and thermal pads when mounting to heatsinks.
Does the adjust pin require a capacitor for noise rejection?
A 25 µF capacitor from ADJ to ground improves supply voltage rejection at low frequencies (e.g., 120 Hz ripple), especially under heavy load. This capacitor also reduces sensitivity to PCB layout noise but is not required for basic stability-only recommended for high-PSRR applications.
LD1585CD2M18R Specifications
- Product attributes
- Attribute value
- Manufacturer:
- STMicroelectronics
- Series:
- -
- Package/Case:
- TO-263-4, D2PAK (3 Leads + Tab), TO-263AA
- 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-3
LD1585CD2M18R FAQ
1.How can I place an order for LD1585CD2M18R through Aetrix?
Please submit a Request for Quotation (RFQ) for LD1585CD2M18R 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 LD1585CD2M18R reliable?
The price and inventory of LD1585CD2M18R are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LD1585CD2M18R is usually 5 days.
3.What payment methods are accepted for LD1585CD2M18R?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LD1585CD2M18R transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LD1585CD2M18R?
LD1585CD2M18R orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LD1585CD2M18R 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 LD1585CD2M18R?
For technical support, including LD1585CD2M18R datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LD1585CD2M18R requirements.
6.How does Aetrix verify that LD1585CD2M18R is sourced from the original manufacturer or authorized distributors?
All LD1585CD2M18R 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 LD1585CD2M18R meets industry standards.
7.What is the process for return or replacement of LD1585CD2M18R?
All LD1585CD2M18R units undergo pre-shipment inspection (PSI). If there is an issue with LD1585CD2M18R, 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 LD1585CD2M18R part is unused and in its original packaging.
Return procedure for LD1585CD2M18R:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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