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STMicroelectronics LD1085D2M-R
- Part No.:
- LD1085D2M-R
- Manufacturer:
- STMicroelectronics
- Package:
- TO-263-4, D2PAK (3 Leads + Tab), TO-263AA
- Datasheet:
-
LD1085D2M-R.pdf
- Description:
- IC REG LINEAR POS ADJ 3A D2PAK-3
- Quantity:
- Payment:
- Shipping:
Inventory:9,092
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Product details
Overview
LD1085D2M-R from STMicroelectronics is an adjustable low-dropout linear voltage regulator delivering up to 3 A output current with 1.3 V typical dropout at full load, ±1% output voltage tolerance at 25 °C, and operation across –40 °C to +125 °C. It uses a precision 1.25 V internal reference and requires only a 10 µF output capacitor for stability, targeting power rails in industrial motor drives and embedded control systems.
For engineers reviewing the LD1085D2M-R datasheet, LD1085D2M-R pinout, LD1085D2M-R application, or LD1085D2M-R equivalent, this page provides verified technical context, real-world design meaning of specifications, validated pin functions, application-specific implementation guidance, and confirmed alternative parts with documented functional differences.
Technical Context
The LD1085D2M-R implements an NPN-based LDO architecture with on-chip trimming for tight output voltage accuracy. Its adjust pin (ADJ) accepts a resistive divider to set output voltage per VO = VREF × (1 + R1/R2), where VREF = 1.25 V (±1%). Internal thermal and current limiting protect against overload and junction overheating.
Unlike PNP regulators, quiescent current flows into the load rather than being wasted, improving efficiency at light loads. Dropout voltage remains stable across temperature (–40 °C to +125 °C) and load (0–3 A), with typical 1.3 V at 3 A and <1.5 V maximum - enabling use with input voltages as low as 3.4 V for 1.8 V output.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Output Current | Up to 3 A continuous - supports high-current microcontroller cores, FPGAs, and analog subsystems without external pass transistors. |
| Dropout Voltage | 1.3 V typ. at 3 A - enables regulation from 5 V input to 3.3 V rail or 4.2 V input to 2.5 V rail with margin. |
| Reference Voltage | 1.25 V ±1% - sets precise output via external resistor divider; enables custom voltages from 1.8 V to 24 V. |
| Output Tolerance | ±1% at 25 °C, ±2% over full temperature range - ensures reliable logic-level compliance for 3.3 V/2.5 V I/O domains. |
| Operating Temp | –40 °C to +125 °C junction - qualified for industrial control cabinets, motor drive PCBs, and under-hood auxiliary supplies. |
| Quiescent Current | 5–10 mA - scales with load (flows into output), reducing no-load power loss vs. traditional PNP LDOs. |
| Stability Cap | 10 µF minimum ceramic or tantalum - simplifies layout with low-ESR capacitors; no ESR requirements or compensation network needed. |
Pinout & Package
LD1085D2M-R is supplied in the D²PAK (TO-263) surface-mount package - thermally optimized for high-power dissipation with exposed drain pad soldered to PCB copper pour.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| IN | Input voltage supply | Accepts 2.85 V to 30 V DC; must be ≥ VO + Vd (e.g., ≥4.6 V for 3.3 V output at 3 A). |
| OUT | Regulated output | Delivers adjustable voltage set by ADJ pin divider; connects directly to load and output capacitor. |
| ADJ | Feedback reference node | Senses output via resistor divider; adjusts VO = 1.25 V × (1 + R1/R2); draws only 55–120 µA. |
Key Features
| Feature | Design Value |
|---|---|
| Thermal shutdown | Activates at ~165 °C junction temperature - prevents permanent damage during sustained overload or poor heatsinking. |
| Current limiting | Short-circuit current ≥3.2 A at 5 V dropout - sustains safe fault condition without latch-up or destruction. |
| Supply rejection | 60–72 dB at 120 Hz - suppresses ripple from upstream switching converters feeding the LDO input. |
| Noise performance | 0.003% RMS output noise (10 Hz–10 kHz) - suitable for noise-sensitive analog circuits like ADC references or op-amp supplies. |
| Load regulation | ≤20 mV over 0–3 A load change - maintains stable voltage during dynamic CPU/FPGA core current transients. |
Applications
| Industrial PLC I/O Module | Motor Drive Control Board |
|---|---|
|
Use Scenario: Powering isolated digital I/O channels and analog sensor signal conditioning circuitry in programmable logic controllers. IC Role / Device Role / Timing Role: Primary 3.3 V/2.5 V local regulator supplying FPGA configuration banks, ADC drivers, and optocoupler bias rails. Use Value: ±1% output tolerance ensures consistent logic thresholds across temperature; 3 A capacity supports simultaneous activation of multiple I/O channels. |
Use Scenario: Generating gate driver and MCU core supplies from a shared 12 V intermediate bus in brushless DC motor inverters. IC Role / Device Role / Timing Role: Adjustable LDO providing 5 V for MCU and 3.3 V for isolated gate driver ICs, decoupled from noisy inverter switching noise. Use Value: 72 dB supply rejection attenuates 12 V bus ripple; 1.3 V dropout allows efficient 12 V → 5 V conversion even at elevated ambient temperatures. |
| Telecom Remote Radio Unit | Medical Diagnostic Imaging Subsystem |
|
Use Scenario: Local regulation for RF front-end ICs and baseband processors in outdoor small-cell radio units operating in wide ambient ranges. IC Role / Device Role / Timing Role: Fixed-output variant (e.g., LD1085D2M33R) or adjustable version delivering clean 3.3 V/2.5 V to sensitive RF synthesizers and ADCs. Use Value: 0.003% RMS noise minimizes phase noise degradation in LO generation; –40 °C to +125 °C rating covers outdoor enclosure extremes. |
Use Scenario: Powering low-noise analog front-ends and timing-critical FPGA fabric in ultrasound beamforming modules. IC Role / Device Role / Timing Role: Low-noise, high-accuracy LDO generating 1.8 V for ADC reference buffers and 2.5 V for clock distribution ICs. Use Value: Tight ±1% tolerance guarantees consistent sampling accuracy; thermal regulation of 0.008 %/W prevents drift during extended imaging sessions. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar adjustable LDO regulator applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| LM317LDR2G | 200 mA max output, 2 V min dropout, ±2% output tolerance, 80 µA quiescent current | Not suitable for >500 mA loads; higher dropout limits low-VIN use cases | Select only for low-current, cost-sensitive designs where 3 A capability is unnecessary |
| TLV1117LV33 | Fixed 3.3 V output, 800 mA max, 0.6 V dropout at 800 mA, ±2% tolerance, SOT-223 package | Cannot be adjusted; limited current and thermal capability vs. D²PAK | Use only for space-constrained, fixed-voltage, sub-1 A applications - not a functional replacement |
Compared with LM317LDR2G and TLV1117LV33, the LD1085D2M-R uniquely delivers 3 A output with 1.3 V dropout and ±1% accuracy in a thermally robust D²PAK package - making it the sole choice for high-current, precision-adjustable industrial power rails.
Availability
LD1085D2M-R is available at Aetrix Electronics and suitable for industrial motor drives, telecom remote radio units, medical diagnostic subsystems, and embedded control systems requiring stable component supply across extended temperature and long production lifecycles.
Supply support for LD1085D2M-R 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 silicon solutions for automotive, industrial, and consumer markets since 1987.
The LD1085 belongs to ST's high-current linear regulator product line, engineered specifically for industrial-grade power management where reliability, thermal robustness, and tight output accuracy outweigh switching efficiency trade-offs.
FAQ
What output voltage range can be set using the LD1085D2M-R?
The LD1085D2M-R is an adjustable regulator with a 1.25 V internal reference. Using an external resistor divider on the ADJ pin, output voltage can be set from 1.8 V up to 24 V, constrained only by the 30 V maximum input voltage rating and minimum load current requirement of 3 mA.
Does the LD1085D2M-R require a minimum load current to maintain regulation?
Yes - the LD1085D2M-R requires a minimum load current of 3 mA (typical) to ensure stable regulation and prevent output voltage rise. This is satisfied by most downstream logic or analog loads; if unused, a bleed resistor from OUT to GND may be added.
Can the LD1085D2M-R be used in parallel for higher current?
No - the LD1085D2M-R is not designed for parallel operation. Its output voltage tolerance and load regulation characteristics prevent balanced current sharing. For >3 A, select a higher-current regulator or switch to a switching solution.
Is the D²PAK package of LD1085D2M-R RoHS-compliant and lead-free?
Yes - the LD1085D2M-R is manufactured in ST's ECOPACK®-compliant D²PAK package, meeting RoHS Directive 2011/65/EU and featuring lead-free terminations and halogen-free molding compound per ST's environmental specifications.
LD1085D2M-R 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:
- Active
- Output Configuration:
- Positive
- Output Type:
- Adjustable
- Number of Regulators:
- 1
- Voltage - Input (Max):
- 30V
- Voltage - Output (Min/Fixed):
- 1.25V
- Voltage - Output (Max):
- 28.5V
- Voltage Dropout (Max):
- 1.5V @ 3A
- Current - Output:
- 3A
- Current - Quiescent (Iq):
- 10 mA
- Current - Supply (Max):
- -
- PSRR:
- 72dB (120Hz)
- Control Features:
- -
- Protection Features:
- Over Current, Over Temperature
- Operating Temperature:
- -40°C ~ 125°C
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- D2PAK-3
LD1085D2M-R FAQ
1.How can I place an order for LD1085D2M-R through Aetrix?
Please submit a Request for Quotation (RFQ) for LD1085D2M-R 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 LD1085D2M-R reliable?
The price and inventory of LD1085D2M-R are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LD1085D2M-R is usually 5 days.
3.What payment methods are accepted for LD1085D2M-R?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LD1085D2M-R transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LD1085D2M-R?
LD1085D2M-R orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LD1085D2M-R 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 LD1085D2M-R?
For technical support, including LD1085D2M-R datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LD1085D2M-R requirements.
6.How does Aetrix verify that LD1085D2M-R is sourced from the original manufacturer or authorized distributors?
All LD1085D2M-R 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 LD1085D2M-R meets industry standards.
7.What is the process for return or replacement of LD1085D2M-R?
All LD1085D2M-R units undergo pre-shipment inspection (PSI). If there is an issue with LD1085D2M-R, 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 LD1085D2M-R part is unused and in its original packaging.
Return procedure for LD1085D2M-R:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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