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onsemi NCP1117ST285T3
- Part No.:
- NCP1117ST285T3
- Manufacturer:
- onsemi
- Package:
- TO-261-4, TO-261AA
- Datasheet:
-
NCP1117ST285T3.pdf
- Description:
- IC REG LINEAR 2.85V 1A SOT223
- Quantity:
- Payment:
- Shipping:
Inventory:3,745
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Product details
Overview
NCP1117ST285T3 from onsemi is a 2.85 V fixed-output, 1.0 A low-dropout linear voltage regulator in SOT-223 package, featuring 1.2 V max dropout at 800 mA, ±1.0% output voltage accuracy, and thermal shutdown protection. It delivers stable point-of-load regulation for SCSI termination, hard drive controllers, and post-regulation in switching power supplies.
For engineers reviewing the NCP1117ST285T3 datasheet, pinout, applications, or equivalent options, key selection criteria include dropout voltage at 800 mA, load regulation (≤3.8 mV), ripple rejection (62 dB at 120 Hz), thermal resistance (160°C/W junction-to-ambient), and compatibility with 4.25–10 V input range for 2.85 V output.
Technical Context
The NCP1117ST285T3 uses an internal bandgap reference trimmed to ±1.0% and employs safe operating area (SOA) compensation to maintain stability under varying load and temperature conditions. Its dropout behavior is characterized by 1.07 V at 800 mA over temperature, enabling operation with minimal headroom above output voltage.
It integrates current limiting, thermal shutdown at ~175°C, and reverse-bias protection via internal diodes. The device requires no minimum load for regulation and supports input voltages up to 20 V, with recommended input capacitance of 10 µF ceramic and output capacitance ≥4.7 µF with ESR between 33 mΩ and 2.2 Ω.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Output Voltage | 2.85 V ±1.0% - ensures precise termination voltage for active SCSI bus compliance |
| Max Dropout Voltage | 1.20 V at 800 mA - enables stable regulation with only 4.05 V min input (2.85 V + 1.20 V) |
| Output Current | 1.0 A continuous - sufficient for high-current point-of-regulation in storage controllers |
| Input Voltage Range | 4.25 V to 10 V - optimized for post-regulation after buck converters or 5 V rail conditioning |
| Load Regulation | ≤3.8 mV (0–800 mA) - maintains tight output stability across full load range |
| Ripple Rejection | 62 dB at 120 Hz - suppresses low-frequency switching noise from upstream SMPS stages |
| Thermal Resistance | 160°C/W (Junction-to-Ambient, SOT-223, min pad) - dictates heatsink requirement for >0.5 W dissipation |
| Quiescent Current | 5.5 mA - low bias current minimizes standby power loss in always-on subsystems |
Pinout & Package
SOT-223 package (Case 318H) with exposed metal tab thermally connected to Pin 2 (Output). Standard 3-pin configuration optimized for surface-mount PCB layout and thermal conduction through copper pour.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1 | Ground / Adjust | Reference node for internal error amplifier; must be low-impedance connection to system ground plane |
| 2 | Output | Main regulated 2.85 V supply; heatsink tab is electrically tied to this pin for thermal management |
| 3 | Input | Unregulated input (4.25–10 V); requires local 10 µF bypass capacitor placed adjacent to pin |
Key Features
| Feature | Design Value |
|---|---|
| No minimum load requirement | Enables stable regulation even at zero load-critical for low-power standby modes in storage interfaces |
| Internal thermal shutdown | Activates at ~175°C junction temperature, preventing catastrophic failure during transient overload or poor heatsinking |
| ±1.0% output voltage accuracy | Guarantees 2.821–2.879 V output across temperature and line/load variations-meets SCSI-2/3 active termination specs |
| Safe operating area (SOA) compensation | Prevents secondary breakdown during short-circuit or high-VIN–VOUT transients without external foldback circuitry |
| Pb-free SOT-223 package | RoHS-compliant lead finish with standard reflow profile compatibility for automated assembly |
Applications
| Active SCSI Bus Termination | Hard Drive Controller Power |
|---|---|
Use Scenario: Termination of differential SCSI-2/3 buses requiring precise 2.85 V bias voltage. IC Role / Device Role / Timing Role: Fixed-output LDO providing stable termination voltage referenced to bus signaling levels. Use Value: Maintains impedance matching and signal integrity across wide temperature ranges without external trimming. | Use Scenario: Local regulation for ASIC/FPGA I/O banks and servo control logic in 2.5" and 3.5" HDDs. IC Role / Device Role / Timing Role: Point-of-load regulator delivering clean 2.85 V to sensitive analog front-end circuits. Use Value: Low dropout and high PSRR ensure stable timing margins and reduced bit error rates under dynamic load. |
| Switching Power Supply Post-Regulation | Battery Charger Reference Stage |
Use Scenario: Final-stage regulation after a 5 V buck converter to eliminate switching ripple in noise-sensitive loads. IC Role / Device Role / Timing Role: Low-noise linear post-regulator filtering high-frequency artifacts from upstream SMPS. Use Value: 62 dB ripple rejection at 120 Hz and 0.003% RMS noise enable clean analog sensor or ADC reference rails. | Use Scenario: Precision voltage reference for charge termination comparators in Li-ion battery charging ICs. IC Role / Device Role / Timing Role: Stable 2.85 V reference source for voltage threshold detection in charge control loops. Use Value: ±1.0% accuracy and <0.5% temperature drift ensure consistent full-charge detection across -40°C to +125°C. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar fixed-output LDO regulator applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| LD1117S285TR | STMicroelectronics part; 1.0 A rating, 1.1 V dropout at 800 mA, ±2% output tolerance | Higher output tolerance reduces precision in SCSI termination; lower dropout margin allows tighter input headroom | Select when cost sensitivity outweighs ±1.0% accuracy requirement and thermal design accommodates higher RJA |
| TLV1117-285CDCYR | Texas Instruments part; 800 mA max output, 1.2 V dropout at 800 mA, ±2% tolerance, 1.5 µA quiescent current | Lower current rating limits use in high-dynamic-load HDD controllers; ultra-low IQ suits battery-backed systems | Select for portable or energy-harvesting applications where 800 mA suffices and standby current is critical |
Compared with LD1117S285TR and TLV1117-285CDCYR, the NCP1117ST285T3 offers superior output accuracy (±1.0% vs. ±2%), higher output current (1.0 A vs. 0.8 A), and proven robustness in industrial storage environments-making it optimal for mission-critical SCSI and controller power.
Availability
NCP1117ST285T3 is available at Aetrix Electronics and suitable for active SCSI termination, hard drive controller power, and switching power supply post-regulation requiring stable component supply, RoHS compliance, and automotive-grade traceability.
Supply support for NCP1117ST285T3 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
onsemi (formerly ON Semiconductor) is a global semiconductor supplier focused on energy-efficient electronics, with leadership in power management, analog, and sensing technologies.
The NCP1117 series was designed for high-reliability point-of-load regulation in consumer, industrial, and automotive systems-emphasizing low dropout, thermal robustness, and ±1.0% accuracy without minimum load constraints.
FAQ
What is the maximum input voltage for the NCP1117ST285T3?
The NCP1117ST285T3 supports a maximum input voltage of 20 V, but its recommended operating input range for 2.85 V output is 4.25 V to 10 V per datasheet specifications. Exceeding 10 V increases power dissipation and thermal stress without functional benefit for this fixed-output variant.
Does the NCP1117ST285T3 require an external capacitor on the output pin?
Yes, the NCP1117ST285T3 requires a minimum 4.7 µF output capacitor with ESR between 33 mΩ and 2.2 Ω for stability. Ceramic, tantalum, or aluminum electrolytic types are acceptable if they meet these parameters across the full operating temperature range.
Is the NCP1117ST285T3 pin-compatible with older regulators like the LM317?
The NCP1117ST285T3 is not pin-compatible with the LM317 because it is a fixed-output device with Ground/Adjust (Pin 1), Output (Pin 2), and Input (Pin 3) pinout, whereas the LM317 uses Adjust (Pin 1), Output (Pin 2), and Input (Pin 3). However, the NCP1117 adjustable variants (e.g., NCP1117STAT3G) are pin-compatible with LM317.
What thermal considerations apply to the NCP1117ST285T3 in SOT-223 package?
The NCP1117ST285T3 in SOT-223 has a junction-to-ambient thermal resistance of 160°C/W with minimum PCB copper pad. To avoid thermal shutdown, power dissipation must stay below PD = (150°C − TA) / 160°C/W. For 50°C ambient, max safe dissipation is 0.625 W-requiring heatsinking or derating above that level.
Can the NCP1117ST285T3 be used in automotive applications?
The NCP1117ST285T3 is not AEC-Q100 qualified. For automotive use, the NCV1117ST285T3 (automotive-grade variant) should be selected-it features PPAP capability, extended temperature range (−40°C to +125°C), and unique site controls required for vehicle systems.
NCP1117ST285T3 Specifications
- Product attributes
- Attribute value
- Manufacturer:
- onsemi
- Series:
- -
- Package/Case:
- TO-261-4, TO-261AA
- Packaging:
- Tape & Reel (TR)
- Product Status:
- Obsolete
- Output Configuration:
- Positive
- Output Type:
- Fixed
- Number of Regulators:
- 1
- Voltage - Input (Max):
- 20V
- Voltage - Output (Min/Fixed):
- 2.85V
- Voltage - Output (Max):
- -
- Voltage Dropout (Max):
- 1.2V @ 800mA
- Current - Output:
- 1A
- Current - Quiescent (Iq):
- 10 mA
- Current - Supply (Max):
- -
- PSRR:
- 68dB (120Hz)
- Control Features:
- -
- Protection Features:
- Over Current, Over Temperature
- Operating Temperature:
- 0°C ~ 125°C
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- SOT-223
NCP1117ST285T3 FAQ
1.How can I place an order for NCP1117ST285T3 through Aetrix?
Please submit a Request for Quotation (RFQ) for NCP1117ST285T3 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 NCP1117ST285T3 reliable?
The price and inventory of NCP1117ST285T3 are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for NCP1117ST285T3 is usually 5 days.
3.What payment methods are accepted for NCP1117ST285T3?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for NCP1117ST285T3 transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for NCP1117ST285T3?
NCP1117ST285T3 orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your NCP1117ST285T3 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 NCP1117ST285T3?
For technical support, including NCP1117ST285T3 datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your NCP1117ST285T3 requirements.
6.How does Aetrix verify that NCP1117ST285T3 is sourced from the original manufacturer or authorized distributors?
All NCP1117ST285T3 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 NCP1117ST285T3 meets industry standards.
7.What is the process for return or replacement of NCP1117ST285T3?
All NCP1117ST285T3 units undergo pre-shipment inspection (PSI). If there is an issue with NCP1117ST285T3, 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 NCP1117ST285T3 part is unused and in its original packaging.
Return procedure for NCP1117ST285T3:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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