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onsemi NCP1117ST285T3G
- Part No.:
- NCP1117ST285T3G
- Manufacturer:
- onsemi
- Package:
- TO-261-4, TO-261AA
- Datasheet:
-
NCP1117ST285T3G.pdf
- Description:
- IC REG LINEAR 2.85V 1A SOT223
- Quantity:
- Payment:
- Shipping:
Inventory:4,856
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Product details
Overview
NCP1117ST285T3G from onsemi is a 1.0 A low-dropout positive fixed-voltage linear regulator with 2.85 V output, SOT-223 package, ±1.0% output voltage accuracy, 1.2 V max dropout at 800 mA, and thermal shutdown protection. It delivers stable power for active SCSI termination, hard drive controllers, and switching supply post-regulation.
For engineers reviewing the NCP1117ST285T3G datasheet, pinout, applications, or equivalent options, key selection criteria include dropout voltage at 800 mA, load regulation under 3.8 mV, ripple rejection of 62 dB at 120 Hz, thermal shutdown activation at ~175°C, and compatibility with 4.7 µF minimum output capacitance.
Technical Context
The NCP1117ST285T3G implements a bandgap-referenced error amplifier with internal current limiting and safe operating area compensation. Its fixed 2.85 V output is trimmed on-chip to ±1.0% over temperature, eliminating external resistor networks.
It operates across an input range of 4.25 V to 10 V while maintaining regulation with zero minimum load requirement. Internal thermal shutdown activates at approximately 175°C, and the device supports up to 20 V absolute maximum input voltage.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Output Voltage | 2.85 V ±1.0% (guaranteed accuracy over full operating temperature range) |
| Max Dropout Voltage | 1.20 V at 800 mA (enables operation with only 4.05 V input for 2.85 V output) |
| Output Current | 1.0 A continuous (internally current-limited; derates above 125°C ambient) |
| Line Regulation | 0.8 mV (measured over 4.25–10 V input range at no load) |
| Load Regulation | 3.8 mV (change in output voltage from 0 to 800 mA load at fixed input) |
| Ripple Rejection | 62 dB at 120 Hz (suppresses AC line ripple in post-regulation applications) |
| Quiescent Current | 5.5 mA (low bias current enables high efficiency at light loads) |
| Thermal Shutdown | ~175°C junction temperature (self-protecting during overload or poor heatsinking) |
Pinout & Package
Package: SOT-223 (Case 318H), surface-mount, thermally enhanced with exposed metal tab connected to Pin 2 (Output).
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1 | Ground / Adjust | Reference node for internal voltage divider; connects to system ground for fixed-output operation |
| 2 | Output | Regulated 2.85 V supply rail; electrically tied to heatsink tab for thermal conduction |
| 3 | Input | Unregulated DC input (4.25–10 V); requires local 10 µF bypass capacitor |
Key Features
| Feature | Design Value |
|---|---|
| No minimum load requirement | Maintains regulation down to 0 mA output - simplifies design for intermittent-load systems |
| ±1.0% output voltage accuracy | Reduces need for post-production calibration in precision 2.85 V SCSI termination |
| 1.2 V dropout at 800 mA | Enables use with low-headroom sources such as 5 V SMPS outputs or battery packs |
| Integrated thermal shutdown | Prevents permanent damage during sustained overload or inadequate PCB copper area |
| 20 V absolute max input rating | Provides robustness against transient overvoltage events on input rails |
| Pb-free SOT-223 package | Complies with RoHS and JEDEC moisture sensitivity level 3 (MSL3) handling requirements |
Applications
| Active SCSI Bus Termination | Hard Drive Controller Power |
|---|---|
Use Scenario: Provides precise 2.85 V termination voltage for differential SCSI-2/3 bus signaling in server backplanes and storage enclosures. IC Role / Device Role / Timing Role: Fixed-output linear regulator delivering stable, low-noise 2.85 V reference for parallel bus termination resistors. Use Value: Matches SCSI specification's exact 2.85 V requirement with ±1.0% tolerance, ensuring signal integrity and bus reliability without external trimming. | Use Scenario: Supplies clean, regulated 2.85 V to ASICs and interface logic on enterprise-grade HDD controller boards. IC Role / Device Role / Timing Role: Point-of-load (POL) regulator for low-voltage logic domains requiring tight voltage stability under dynamic load transients. Use Value: Delivers 1.0 A with 3.8 mV load regulation and fast transient response (<100 µs recovery), minimizing voltage droop during burst data transfers. |
| Switching Supply Post-Regulation | Battery Charger Reference |
Use Scenario: Used downstream of buck converters to reduce residual switching noise and improve PSRR in sensitive analog subsystems. IC Role / Device Role / Timing Role: Low-noise linear post-regulator filtering high-frequency ripple from switching stages. Use Value: Achieves 62 dB ripple rejection at 120 Hz and 0.003% RMS output noise, enabling clean power for ADC references or PLLs. | Use Scenario: Generates accurate 2.85 V reference for charge management ICs in multi-cell Li-ion battery chargers. IC Role / Device Role / Timing Role: Precision voltage reference source for battery voltage monitoring and charge termination thresholds. Use Value: Maintains ±1.0% output accuracy over −40°C to +125°C, ensuring consistent charge cutoff across environmental conditions. |
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 | 2.85 V fixed, 1.0 A, SOT-223, ±2% accuracy, 1.3 V dropout at 800 mA | Lower accuracy and higher dropout limit usable headroom and precision in SCSI termination | Acceptable where ±2% tolerance and 0.1 V higher dropout are acceptable; lower cost alternative |
| TLV1117-285CDCYR | 2.85 V fixed, 800 mA, SOT-223, ±1% accuracy, 1.2 V dropout at 800 mA, lower IQ (4.5 mA) | 800 mA max output limits use in high-current HDD controller designs | Preferred for space-constrained, low-IQ applications below 800 mA; not suitable for full 1.0 A loads |
Compared with LD1117S285TR and TLV1117-285CDCYR, the NCP1117ST285T3G uniquely combines 1.0 A capability, ±1.0% accuracy, and 1.2 V dropout in a single Pb-free SOT-223 package - making it optimal for high-reliability SCSI termination and industrial hard drive controllers where both precision and current margin are critical.
Availability
NCP1117ST285T3G is available at Aetrix Electronics and suitable for active SCSI termination, hard drive controller power, and switching supply post-regulation requiring stable component supply, long-term lifecycle support, and RoHS-compliant sourcing.
Supply support for NCP1117ST285T3G 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 sensor technologies.
The NCP1117 series was designed specifically for high-current, low-dropout point-of-load regulation in consumer, industrial, and computing applications - emphasizing thermal robustness, precision output, and drop-in compatibility with legacy LM317-based designs.
FAQ
What is the maximum input voltage for the NCP1117ST285T3G?
The NCP1117ST285T3G supports a maximum input voltage of 20 V as an absolute rating. However, for reliable operation with 2.85 V output, the recommended input range 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 NCP1117ST285T3G require an output capacitor, and what value is needed?
Yes, the NCP1117ST285T3G requires a minimum 4.7 µF output capacitor with ESR between 33 mΩ and 2.2 Ω for stability. A 10 µF tantalum or ceramic capacitor is commonly used and validated in the datasheet for transient performance and ripple suppression in applications like SCSI termination.
Is the NCP1117ST285T3G pin-compatible with the LM317?
No - the NCP1117ST285T3G is not pin-compatible with the LM317. While the NCP1117 series is functionally compatible and pin-compatible with *some* LM317 derivative footprints in adjustable configurations, the NCP1117ST285T3G is a fixed 2.85 V SOT-223 device with Pin 1 = Ground, Pin 2 = Output, Pin 3 = Input - differing from LM317's ADJ/VOUT/IN pinout order.
What thermal considerations apply to the NCP1117ST285T3G in SOT-223 package?
The NCP1117ST285T3G's SOT-223 package uses the exposed tab (connected to Pin 2) as a thermal path. With a 1-inch² 2 oz. copper pad, RJA drops to ~160°C/W. At 800 mA and 1.2 V dropout, power dissipation is ~0.96 W - requiring ≥2.5 cm² copper area to maintain TJ < 125°C at 50°C ambient, per Figure 21.
Can the NCP1117ST285T3G be used in automotive applications?
The NCP1117ST285T3G is not AEC-Q100 qualified. For automotive use, the NCV1117ST285T3G (AEC-Q100 Grade 1, −40°C to +125°C) is the qualified variant. The NCP1117ST285T3G is rated for 0°C to +125°C ambient and intended for industrial and commercial equipment.
NCP1117ST285T3G 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
NCP1117ST285T3G FAQ
1.How can I place an order for NCP1117ST285T3G through Aetrix?
Please submit a Request for Quotation (RFQ) for NCP1117ST285T3G 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 NCP1117ST285T3G reliable?
The price and inventory of NCP1117ST285T3G are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for NCP1117ST285T3G is usually 5 days.
3.What payment methods are accepted for NCP1117ST285T3G?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for NCP1117ST285T3G transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for NCP1117ST285T3G?
NCP1117ST285T3G orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your NCP1117ST285T3G 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 NCP1117ST285T3G?
For technical support, including NCP1117ST285T3G datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your NCP1117ST285T3G requirements.
6.How does Aetrix verify that NCP1117ST285T3G is sourced from the original manufacturer or authorized distributors?
All NCP1117ST285T3G 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 NCP1117ST285T3G meets industry standards.
7.What is the process for return or replacement of NCP1117ST285T3G?
All NCP1117ST285T3G units undergo pre-shipment inspection (PSI). If there is an issue with NCP1117ST285T3G, 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 NCP1117ST285T3G part is unused and in its original packaging.
Return procedure for NCP1117ST285T3G:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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