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onsemi FAN1086S285X
- Part No.:
- FAN1086S285X
- Manufacturer:
- onsemi
- Package:
- TO-261-4, TO-261AA
- Datasheet:
-
FAN1086S285X.pdf
- Description:
- IC REG LIN 2.85V 1.5A SOT223-4
- Quantity:
- Payment:
- Shipping:
Inventory:3,397
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Product details
Overview
FAN1086S285X from Fairchild Semiconductor is a fixed-output 2.85V, 1.5A low-dropout linear regulator in SOT-223 package, optimized for active SCSI terminators and motherboard clock supplies with 1.5V dropout at full load and 0.05% typical load regulation.
For engineers reviewing the FAN1086S285X datasheet, pinout, applications, or equivalent options, key selection criteria include guaranteed 2.85V output tolerance (±2%), thermal shutdown at 155°C, adjustable/trimmable current limit, and compatibility with 10µF–22µF output capacitance for stability in low-noise power domains.
Technical Context
The FAN1086S285X uses an NPN-based pass transistor architecture, enabling quiescent current to flow into the load rather than being wasted-improving efficiency over PNP regulators. Its reference voltage is internally trimmed to 1.25V ±2%, and output is set by internal resistor network for fixed 2.85V operation.
Thermal protection includes junction-sensing shutdown at 155°C with 10°C hysteresis, and thermal resistance is 15°C/W (junction-to-case) in the SOT-223 package when soldered to 0.5 in² copper area. Ripple rejection is 72dB at 120Hz with 22µF tantalum output capacitor.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Output Voltage | Fixed 2.85V ±2% - ensures precise termination voltage for SCSI-2/3 active bus termination compliance. |
| Max Output Current | 1.5A - supports high-current termination loads without external boost circuitry. |
| Dropout Voltage | 1.5V max at 1.5A - enables operation from 4.35V input, critical for post-regulation after 5V switching supplies. |
| Load Regulation | 0.05% typical - maintains stable 2.85V across 10mA–1A load range, minimizing bus voltage drift. |
| Ripple Rejection | 72dB at 120Hz - suppresses switching noise from upstream DC/DC converters feeding motherboard clocks. |
| Quiescent Current | 4–13mA - flows into load, not ground, improving system efficiency vs. traditional PNP LDOs. |
| Thermal Shutdown | 155°C with 10°C hysteresis - prevents permanent damage during sustained overload or poor PCB heatsinking. |
Pinout & Package
Package: 4-lead plastic SOT-223 with exposed tab connected to VOUT; requires ≥0.5 in² copper pad on backside ground plane for ΘJA ≤30°C/W.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1 (ADJ/GND) | Adjust/Ground reference | Ground return path for internal reference; tied to system GND in fixed-voltage configuration. |
| 2 (OUT) | Regulated output | Delivers 2.85V to load; tab is electrically connected to this pin for thermal conduction. |
| 3 (IN) | Input supply | Accepts 4.35V–7V input; dropout headroom must be maintained for regulation. |
| Tab | Output voltage node | Internally bonded to OUT pin; must be soldered to large copper area for thermal management. |
Key Features
| Feature | Design Value |
|---|---|
| Low dropout voltage | 1.5V max at 1.5A enables use with marginal input margins (e.g., 5V rail feeding 2.85V SCSI termination). |
| Trimmed current limit | 1.6–2.0A short-circuit current ensures predictable fault behavior without external current-sense components. |
| On-chip thermal limiting | 155°C shutdown with hysteresis protects against PCB-level thermal runaway during sustained overload. |
| Load-efficient quiescent current | 4–13mA flows into load-not ground-reducing total system power loss in battery-sensitive or high-efficiency designs. |
| Stable with low-ESR capacitors | Operates reliably with 10µF–22µF tantalum or ceramic output caps, simplifying layout in space-constrained motherboard zones. |
Applications
| Active SCSI Termination | 5V-to-2.85V Post-Regulation |
|---|---|
Use Scenario: Providing stable, low-noise termination voltage to SCSI-2/3 parallel bus lines under dynamic load conditions. IC Role / Device Role / Timing Role: Fixed-output LDO delivering precise 2.85V to active terminator ICs or resistor networks on SCSI host adapters. Use Value: Eliminates need for discrete Zener + transistor termination, reducing component count and improving voltage accuracy over temperature. | Use Scenario: Cleaning ripple and noise from switched-mode 5V supplies before powering sensitive clock generators or PLLs. IC Role / Device Role / Timing Role: Low-noise post-regulator ensuring clean 2.85V for oscillator biasing and clock buffer ICs on server motherboards. Use Value: 72dB ripple rejection at 120Hz suppresses switching artifacts that could induce jitter in timing circuits. |
| Motherboard Clock Supply | Battery Charger Reference |
Use Scenario: Powering real-time clock (RTC), PCIe reference clocks, or memory controller timing references requiring stable low-voltage rails. IC Role / Device Role / Timing Role: Primary 2.85V source for clock distribution ICs where voltage deviation directly impacts timing margin. Use Value: 0.05% load regulation and <0.02%/W thermal regulation minimize voltage-induced clock skew across operating conditions. | Use Scenario: Generating accurate 2.85V reference for charge voltage sensing or battery fuel gauging circuits in portable systems. IC Role / Device Role / Timing Role: Precision voltage reference generator with tight initial tolerance and long-term stability (0.03% over 1000hrs at 125°C). Use Value: Enables ±0.5% battery voltage measurement accuracy without external trimming or calibration. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar low-dropout linear regulator applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| TLV1117-285CDR | 1A max output, higher dropout (1.2V typ), no thermal hysteresis, SO-8 package | Limited to lower-current termination or reference roles; unsuitable for 1.5A SCSI bus loads | Select only if load current ≤1A and board space allows SO-8 footprint. |
| AP2112K-2.85TRG1 | 600mA max output, 350mV dropout, no adjustable current limit, SOT-23-5 package | Designed for ultra-low-power logic rails-not high-current analog or termination loads | Use only for sub-600mA reference or biasing; cannot replace FAN1086S285X in SCSI termination. |
Compared with TLV1117-285CDR and AP2112K-2.85TRG1, the FAN1086S285X uniquely delivers 1.5A continuous output with 2.85V precision, thermal hysteresis, and SOT-223 thermal performance-making it the only option among the three qualified for active SCSI termination per SCSI-3 specifications.
Availability
FAN1086S285X is available at Aetrix Electronics and suitable for active SCSI termination, motherboard clock supplies, and 5V-to-2.85V post-regulation applications requiring stable component supply and long-lifecycle support.
Supply support for FAN1086S285X 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
Fairchild Semiconductor was a U.S.-based analog and power IC manufacturer acquired by ON Semiconductor in 2016; known for high-reliability linear regulators and power management solutions.
The FAN1086 series was designed specifically for low-voltage, high-current linear regulation in computing infrastructure-emphasizing transient response, minimal dropout, and thermal robustness in dense PCB environments.
FAQ
What is the maximum input voltage rating for the FAN1086S285X?
The FAN1086S285X has an absolute maximum input voltage of 7.5V. Its recommended operating input range is 4.35V to 7V, as specified for the 2.85V fixed version to ensure proper regulation and thermal performance. Exceeding 7.5V risks permanent device damage due to internal junction breakdown.
Does the FAN1086S285X require an external output capacitor, and what value is recommended?
Yes, the FAN1086S285X requires an external output capacitor for stability. The datasheet specifies 10µF to 22µF tantalum or low-ESR ceramic capacitors. Using values outside this range-especially below 10µF-may cause oscillation or poor transient response, particularly under 1.5A load steps.
Is the FAN1086S285X pin-compatible with other FAN1086 variants like FAN1086S33X?
Yes, all SOT-223-packaged FAN1086 variants-including FAN1086S285X, FAN1086S33X, and FAN1086S5X-share identical 4-pin SOT-223 pinout and mechanical footprint. However, output voltage and input voltage ranges differ; substituting without verifying input headroom may cause regulation failure.
How does the thermal shutdown feature operate in the FAN1086S285X?
The FAN1086S285X activates thermal shutdown at 155°C junction temperature and remains latched off until junction temperature falls by 10°C (to ~145°C) due to its built-in hysteresis. This prevents cycling during marginal thermal conditions and ensures safe cooldown before resuming regulation.
Can the FAN1086S285X be used in adjustable mode, or is it fixed-only?
The FAN1086S285X is a fixed-output variant and cannot be configured as adjustable. It integrates internal resistors to set 2.85V output; only the base part number FAN1086 (without suffix) supports adjustable operation via external R1/R2 feedback network.
FAN1086S285X 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):
- 7.5V
- Voltage - Output (Min/Fixed):
- 2.85V
- Voltage - Output (Max):
- -
- Voltage Dropout (Max):
- 1.5V @ 1.5A
- Current - Output:
- 1.5A
- Current - Quiescent (Iq):
- -
- Current - Supply (Max):
- -
- PSRR:
- 72dB (120Hz)
- Control Features:
- -
- Protection Features:
- Over Current, Over Temperature
- Operating Temperature:
- 25°C ~ 125°C
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- SOT-223-4
FAN1086S285X FAQ
1.How can I place an order for FAN1086S285X through Aetrix?
Please submit a Request for Quotation (RFQ) for FAN1086S285X 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 FAN1086S285X reliable?
The price and inventory of FAN1086S285X are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for FAN1086S285X is usually 5 days.
3.What payment methods are accepted for FAN1086S285X?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for FAN1086S285X transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for FAN1086S285X?
FAN1086S285X orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your FAN1086S285X 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 FAN1086S285X?
For technical support, including FAN1086S285X datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your FAN1086S285X requirements.
6.How does Aetrix verify that FAN1086S285X is sourced from the original manufacturer or authorized distributors?
All FAN1086S285X 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 FAN1086S285X meets industry standards.
7.What is the process for return or replacement of FAN1086S285X?
All FAN1086S285X units undergo pre-shipment inspection (PSI). If there is an issue with FAN1086S285X, 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 FAN1086S285X part is unused and in its original packaging.
Return procedure for FAN1086S285X:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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