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Texas Instruments UCC5618N
- Part No.:
- UCC5618N
- Manufacturer:
- Texas Instruments
- Category:
- Signal Terminators
- Package:
- -
- Datasheet:
-
UCC5618N.pdf
- Description:
- SCSI TERMINATOR, 18-LINE, 110OHM
- Quantity:
- Payment:
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Inventory:10,921
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Product details
Overview
The UCC5618N from Texas Instruments is an 18-line single-ended SCSI active terminator IC designed for termination of SCSI-3, Fast-20 (Ultra), and legacy parallel SCSI buses. It delivers 110 Ω termination impedance with ±5% tolerance, supports TERMPWR from 4.0 V to 5.25 V, draws only 50 µA in disconnect mode, and features 2 pF channel capacitance during high-impedance state-enabling clean signal integrity in hot-plug SCSI backplanes.
For engineers reviewing the UCC5618N datasheet, UCC5618N pinout, UCC5618N application, or UCC5618N equivalent, key selection criteria include its SCSI-3–compliant sourcing/sinking capability (–650 mA / +400 mA), thermal shutdown at 170 °C, Bi-CMOS process, and pin-for-pin compatibility with UC5601/UC5608 in 28-pin SOIC, TSSOP, and PLCC packages.
Technical Context
The UCC5618N integrates a trimmed 2.8 V internal regulator (±0.2 V) and uses Bi-CMOS output stages to simultaneously source full termination current and sink active negation current across all 18 lines. Its disconnect logic responds to a high-level DISCNCT input, forcing all LINE1–LINE18 terminals into high-impedance state with leakage <400 nA and supply current ≤100 µA.
Impedance trimming targets 110 Ω within 5% tolerance and output current alignment to the maximum SCSI-3 specification, directly improving noise margin in Ultra SCSI timing-critical environments. Thermal shutdown (170 °C, 10 °C hysteresis) and current limiting protect against bus fault conditions without external components.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Termination Lines | 18 independent single-ended channels, each with 110 Ω ±5% impedance for SCSI bus termination |
| TERMPWR Range | 4.0 V to 5.25 V - compatible with standard 5 V SCSI power rails and tolerant of rail droop |
| Disconnect Supply Current | 50 µA typical - enables low-power standby in hot-pluggable storage enclosures |
| Channel Capacitance (DISCNCT = high) | 2 pF - minimizes signal distortion and reflections when terminators are inactive |
| Sourcing Current (Termination) | –650 mA max - drives full SCSI-3 termination load across all 18 lines simultaneously |
| Sinking Current (Active Negation) | +400 mA max - supports fast SCSI bus arbitration and signal negation per SPI-3 timing |
| Thermal Shutdown Threshold | 170 °C with 10 °C hysteresis - prevents latch-up or damage during sustained bus faults |
Pinout & Package
UCC5618N is available in 28-pin wide-body SOIC (DWP), TSSOP (PWP), and PLCC (QP) packages. All variants share identical pin numbering and function mapping per the official TI connection diagrams.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| LINE1–LINE18 | Termination channel outputs | Each provides 110 Ω SE termination to one SCSI signal line; high-Z when DISCNCT = high |
| TRMPWR | Terminator power input | Supplies internal regulator and output stage; accepts 4.0–5.25 V; device non-operational if open or 0 V |
| DISCNCT | Disconnect control input | Logic-high or open disables termination and reduces supply current to 50 µA; logic-low enables normal operation |
| REG | Internal 2.8 V regulator output | Provides stable bias for termination circuitry; not intended as system supply rail |
| GND | Signal ground reference | Common return for all termination channels and internal circuitry; must be low-impedance |
Key Features
| Feature | Design Value |
|---|---|
| SCSI Hot-Plugging Compliance | 10 nA typical channel leakage at TRMPWR = 0 V or open - ensures zero bus loading during insertion/removal |
| Trimmed Output Current | Matched to max SCSI-3 spec - maximizes noise margin in Fast-20 (Ultra) timing windows |
| Low Thermal Resistance Packaging | SOIC/TSSOP/PLCC variants optimized for dissipation under full 18-line termination load |
| Integrated Current Limit & Thermal Shutdown | Self-protecting operation during bus shorts or overcurrent - no external protection required |
Applications
| SCSI Backplane Termination | Hot-Pluggable RAID Enclosure |
|---|---|
Use Scenario: Dual-end termination of 18-signal SCSI parallel bus in server backplanes supporting Ultra SCSI (Fast-20) data rates. IC Role / Device Role / Timing Role: Active terminator providing matched 110 Ω impedance and fast negation sinking to meet SPI-3 setup/hold timing. Use Value: Eliminates signal reflections and timing violations at 40 MB/s transfer rates via 2 pF disconnect capacitance and –650 mA sourcing. | Use Scenario: Termination of removable SCSI drive sleds in enterprise storage chassis with live-insertion capability. IC Role / Device Role / Timing Role: High-impedance disconnect mode (50 µA) enables safe insertion/removal while maintaining bus stability. Use Value: Prevents bus glitches during hot-swap via 10 nA leakage and automatic high-Z transition on DISCNCT assertion. |
| Legacy SCSI-2 Workstation Interface | SCSI-to-Fiber Channel Bridge Module |
Use Scenario: Termination of narrow (8-bit) or wide (16-bit) SCSI-2 host adapters in industrial workstations. IC Role / Device Role / Timing Role: Single-chip replacement for resistor networks and discrete transistors - simplifies layout and improves consistency. Use Value: ±5% impedance tolerance and Bi-CMOS switching reduce skew vs. passive solutions, enabling reliable 10 MB/s operation. | Use Scenario: Signal conditioning interface between parallel SCSI bus and serial FC-AL physical layer in bridge cards. IC Role / Device Role / Timing Role: Bus stabilization element ensuring clean signal edges before serialization and clock recovery. Use Value: Low 2 pF channel capacitance preserves edge rate integrity critical for jitter-sensitive FC-AL clock recovery circuits. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar SCSI active termination applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| UC5608 | Same pinout and 18-line SE termination, but lacks thermal shutdown and has higher disconnect current (100 µA vs. 50 µA) | No built-in overtemperature protection; less suitable for dense, fanless enclosures | Select UCC5618N where thermal safety or ultra-low standby power is required |
| UCC5619 | 24-line variant with identical electrical specs, same package footprint, and extended temperature range (–40°C to +85°C) | Supports wider SCSI buses and industrial ambient conditions beyond commercial 0°C–70°C | Select UCC5618N for cost-optimized 18-line systems operating in standard commercial environments |
Compared with UC5608 and UCC5619, the UCC5618N offers the optimal balance of low-power disconnect mode (50 µA), integrated thermal shutdown (170 °C), and precise SCSI-3 current matching - making it the preferred choice for space-constrained, thermally managed 5 V SCSI backplanes requiring guaranteed noise margin at Fast-20 speeds.
Availability
UCC5618N is available at Aetrix Electronics and suitable for SCSI backplane termination, hot-pluggable RAID enclosures, and legacy workstation interfaces requiring stable component supply and long-term lifecycle support.
Supply support for UCC5618N 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
Texas Instruments is a global semiconductor leader delivering analog, embedded processing, and interface solutions for industrial, automotive, and communications markets.
The UCC5618N belongs to TI's SCSI bus terminator product line, engineered specifically for high-speed parallel SCSI signal integrity, hot-plug reliability, and compliance with SCSI-3 and FAST-20 standards in 5 V systems.
FAQ
What is the primary function of the UCC5618N in a SCSI system?
The UCC5618N serves as an 18-line single-ended active terminator for SCSI parallel buses, providing precisely trimmed 110 Ω termination impedance and bidirectional current drive (–650 mA sourcing / +400 mA sinking) to meet SCSI-3 and Fast-20 timing requirements. It ensures signal integrity by minimizing reflections and maintaining noise margin during high-speed transfers. The UCC5618N achieves this while supporting hot-plug operation and low-power disconnect states - critical for modern SCSI backplanes and RAID enclosures.
Does the UCC5618N require external components to operate?
No, the UCC5618N operates autonomously with only TERMPWR (4.0–5.25 V), GND, DISCNCT control, and connection to SCSI signal lines. Its internal 2.8 V regulator (REG pin), trimmed impedance, thermal shutdown, and current limiting are fully integrated. External bypass capacitors on TERMPWR are recommended per TI layout guidelines, but no resistors, transistors, or protection diodes are needed - unlike passive or discrete active termination solutions. This integration simplifies design and improves consistency across the UCC5618N's 18 termination channels.
How does the UCC5618N support hot-plug functionality in SCSI systems?
The UCC5618N supports hot-plug via three key mechanisms: first, it presents <400 nA leakage per channel when TRMPWR = 0 V or open; second, DISCNCT = high forces all 18 LINE pins into high-impedance state with only 50 µA total supply current; third, its Bi-CMOS architecture ensures zero bus contention during insertion. These features allow safe insertion/removal while the SCSI bus remains active - a requirement for RAID sleds and modular storage systems. The UCC5618N meets SCSI hot-plug specifications with 10 nA typical channel leakage under zero-power conditions.
What is the significance of the 2 pF channel capacitance specification for the UCC5618N?
The 2 pF channel capacitance applies specifically when the UCC5618N is in disconnect mode (DISCNCT = high), and it directly impacts signal integrity on interim bus nodes. Unlike higher-capacitance terminators, this ultra-low value prevents signal degradation, ringing, and timing skew when multiple terminators are present but only two ends are active. In Fast-20 (Ultra) SCSI systems running at 40 MB/s, preserving edge rate and minimizing reflection amplitude is essential - and the UCC5618N's 2 pF spec ensures that inactive terminators behave electrically as near-open circuits, not parasitic loads. This value is guaranteed by design per the UCC5618N datasheet.
Is the UCC5618N pin-compatible with other Unitrode SCSI terminators?
Yes, the UCC5618N is pin-for-pin compatible with the UC5601 and UC5608 in all supported packages (SOIC-28, TSSOP-28, PLCC-28). This allows direct drop-in replacement in existing designs without PCB changes. However, the UCC5618N adds thermal shutdown (170 °C), tighter current matching to SCSI-3 limits, and lower disconnect current (50 µA vs. 100 µA in UC5608), making it a functional and reliability upgrade. Engineers upgrading legacy UC560x-based systems can retain layout and firmware while gaining enhanced protection and noise margin - confirmed by TI's official compatibility documentation for the UCC5618N.
UCC5618N Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Texas Instruments
- Series:
- *
- Package/Case:
- -
- Packaging:
- Bulk
- Product Status:
- Active
- Type:
- -
- Number of Terminations:
- -
- Voltage - Supply:
- -
- Operating Temperature:
- -
- Mounting Type:
- -
- Supplier Device Package:
- -
UCC5618N FAQ
1.How can I place an order for UCC5618N through Aetrix?
Please submit a Request for Quotation (RFQ) for UCC5618N 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 UCC5618N reliable?
The price and inventory of UCC5618N are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for UCC5618N is usually 5 days.
3.What payment methods are accepted for UCC5618N?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for UCC5618N transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for UCC5618N?
UCC5618N orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your UCC5618N 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 UCC5618N?
For technical support, including UCC5618N datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your UCC5618N requirements.
6.How does Aetrix verify that UCC5618N is sourced from the original manufacturer or authorized distributors?
All UCC5618N 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 UCC5618N meets industry standards.
7.What is the process for return or replacement of UCC5618N?
All UCC5618N units undergo pre-shipment inspection (PSI). If there is an issue with UCC5618N, 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 UCC5618N part is unused and in its original packaging.
Return procedure for UCC5618N:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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