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NXP Semiconductors SCC2681TC1A44,512
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- Part No.:
- SCC2681TC1A44,512
- Manufacturer:
- NXP Semiconductors
- Package:
- 44-LCC (J-Lead)
- Datasheet:
-
SCC2681TC1A44,512.pdf
- Description:
- IC DUART 1MBPS 44PLCC
- Quantity:
- Payment:
- Shipping:
Inventory:4,727
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Product details
Overview
SCC2681TC1A44 from NXP Semiconductors (formerly Philips) is a dual-channel CMOS universal asynchronous receiver/transmitter (DUART) IC designed for microprocessor-based serial communication systems. It provides two independent full-duplex UART channels, quadruple-buffered receivers, 16-bit programmable counter/timer, and supports up to 115.2 kbaud with 1× or 16× clocking modes - deployed in industrial terminal controllers and legacy embedded communications interfaces.
For engineers reviewing the SCC2681TC1A44 datasheet, SCC2681TC1A44 pinout, SCC2681TC1A44 application, or SCC2681TC1A44 equivalent, key selection considerations include its 44-pin PLCC package, dual-channel independent baud rate programming, 7-bit input/8-bit output ports with change-of-state detection, auto RS-485 turn-around, and interrupt-driven I/O support for polled or interrupt-driven CPU architectures.
Technical Context
The SCC2681TC1A44 implements two fully independent UART channels (A and B), each with separate receiver and transmitter shift registers, holding registers, status/control logic, and programmable data formats (5–8 data bits, odd/even/no/force parity, 1/1.5/2 stop bits in 1/16-bit increments). Each channel supports independent baud rate selection from 22 fixed rates (50–115.2 kbaud), non-standard rates via 16-bit counter/timer, or external 1×/16× clocks.
Its timing architecture integrates an on-chip crystal oscillator (X1/X2), configurable counter/timer with interrupt capability, and dedicated control logic for automatic RTS/CTS flow control, local/remote loopback, echo mode, and multidrop wake-up. The device uses a parallel 8-bit CPU bus interface (D0–D7) with chip enable (CEN), read/write strobes (RDN/WRN), and address lines (A0–A3) for register-level access to control/status registers and I/O ports.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Function | Dual full-duplex asynchronous receiver/transmitter (DUART) with independent channel configuration |
| Supply Voltage | +5 V ±10% - compatible with standard TTL/CMOS logic families and legacy 5 V system rails |
| Max Baud Rate | 115.2 kbaud - supports RS-232, RS-422, and RS-485 physical layers with external transceivers |
| Receiver Buffering | Quadruple-buffered per channel - reduces Rx overrun risk and lowers interrupt overhead in high-throughput systems |
| Counter/Timer | 16-bit programmable - used for baud rate generation, timekeeping, or external event counting with interrupt output |
| I/O Ports | 7-bit multipurpose input port (IP0–IP6) with pull-ups and change-of-state detection; 8-bit output port (OP0–OP7) with individual bit set/reset and auto RS-485 turn-around |
| Interrupt System | Single active-low open-drain INTRN output supporting eight maskable conditions; OP3–OP7 configurable as wire-ORable interrupt outputs |
Pinout & Package
SCC2681TC1A44 is housed in a 44-pin plastic leaded chip carrier (PLCC, SOT187-2) with J-lead profile, suitable for surface-mount assembly and socketed evaluation. The package provides thermal and mechanical stability for industrial temperature operation (0 °C to +70 °C).
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| D0–D7 | Data Bus I/O | Bidirectional 8-bit parallel interface to CPU; D0 = LSB; three-state during idle cycles |
| CEN | Chip Enable Input | Active-low enable for all bus transactions; places D0–D7 in high-impedance state when HIGH |
| RDN / WRN | Read / Write Strobe Inputs | Edge-triggered controls: RDN falling edge initiates read; WRN rising edge latches write data |
| A0–A3 | Address Inputs | Selects among 16 internal registers (control, status, data, timer, I/O ports) for read/write access |
| RxDA / RxDB | Channel A/B Serial Input | Asynchronous receive inputs; sampled on rising edge of 1× clock or falling edge of 16× clock |
| TxDA / TxDB | Channel A/B Serial Output | Transmit outputs held in MARK (HIGH) during idle, disable, or loopback; LSB-first transmission |
| OP0–OP7 | Programmable Output Port | Configurable as general-purpose outputs, RTS/CTS signals, clock outputs, or interrupt sources with auto RS-485 turn-around on OP0/OP1 |
| IP0–IP6 | Programmable Input Port | General-purpose inputs with 100 kΩ pull-ups; assignable as CTS, clock inputs, or change-of-state monitored signals |
| X1/CLK / X2 | Clock Input / Crystal Terminal | Supports on-chip oscillator with 2–4 MHz crystal (e.g., 3.6864 MHz); X2 left unconnected if external clock used |
| INTRN | Interrupt Request Output | Open-drain active-low signal indicating pending interrupt; requires external pull-up resistor |
| RESET | Hardware Reset Input | Active-high signal clearing all internal registers, stopping timer, disabling transmitters, and setting OP0–OP7 HIGH |
Key Features
| Feature | Design Value |
|---|---|
| Fast bus cycle time | Eliminates wait states with CPUs >10 MHz; tAVEL = 0 ns, tRLDA = 15 ns, enabling high-throughput I/O without CPU stalling |
| Independent channel baud rate control | Each receiver and transmitter selects from 22 fixed rates, counter/timer-derived rates, or external 1×/16× clocks - essential for clustered terminal or multidrop applications |
| Auto RS-485 turn-around | OP0 and OP1 automatically toggle direction control during transmit/receive transitions - removes need for external logic or software timing delays |
| Change-of-state detection | Four IP pins (IP0–IP3) support hardware edge-triggered interrupts on input transitions - offloads polling and enables responsive peripheral monitoring |
| False start bit & line break detection | Hardware-level detection of invalid start bits and mid-character breaks - improves robustness in noisy industrial serial environments |
| Wake-up mode for multidrop | Enables slave stations to detect address-matched characters and exit low-power sleep - reduces system power in distributed terminal networks |
Applications
| Industrial Terminal Controller | Legacy POS System Interface |
|---|---|
|
Use Scenario: Central controller managing multiple serial-connected point-of-sale terminals, barcode scanners, and receipt printers over RS-485 multidrop bus. IC Role / Device Role / Timing Role: DUART handles simultaneous bidirectional communication across two independent serial links - one for master-to-slave command distribution, another for slave response aggregation. Use Value: Quadruple buffering prevents data loss at 38.4 kbaud under burst traffic; auto RS-485 turn-around on OP0/OP1 ensures reliable half-duplex timing without firmware intervention. |
Use Scenario: Back-office server interfacing with legacy cash registers and magnetic stripe readers using RS-232 and custom protocol framing. IC Role / Device Role / Timing Role: SCC2681TC1A44 acts as host-side UART bridge, converting parallel CPU bus commands into asynchronous serial streams with precise start/stop/parity timing. Use Value: Programmable 1/16-bit stop bit increments and force parity mode enable compatibility with proprietary protocols requiring non-standard framing not supported by basic 16550-style UARTs. |
| Telecom Line Card Management | Embedded Test Equipment I/O |
|
Use Scenario: Line card in telecom access equipment providing out-of-band management via serial console ports for DSLAM or ONU modules. IC Role / Device Role / Timing Role: Dual-channel DUART serves as dedicated management interface: Channel A for local debug console, Channel B for remote alarm reporting via modem link. Use Value: Independent baud rate selection allows 9600 bps console and 115.2 kbaud alarm reporting simultaneously; wake-up mode reduces standby power during idle periods. |
Use Scenario: Automated test fixture communicating with DUTs via TTL-level serial commands while monitoring status via discrete I/O lines. IC Role / Device Role / Timing Role: SCC2681TC1A44 functions as intelligent serial I/O hub - UART channels handle command/response, while IP/OP ports monitor test fixtures and control relays. Use Value: Change-of-state detection on IP0–IP3 triggers immediate interrupt on DUT fault signals; 8-bit output port drives up to eight relay drivers with individual bit set/reset for precise test sequencing. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar dual UART applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| SCC2692AC1A44 | Successor with enhanced ESD rating (±4 kV HBM), extended temperature range (–40 °C to +85 °C), and improved AC timing margins | Required for new designs targeting extended industrial environments or higher reliability certification | Preferred for new designs where long-term supply continuity and wider temp range are critical |
| TL16C2550IPM | TI dual UART with FIFO (16-byte depth per channel), hardware flow control (RTS/CTS), and PCI-compatible bus interface | Designed for PC add-in cards and systems requiring deeper buffering and plug-and-play compatibility | Choose when FIFO buffering and standard PC bus integration outweigh legacy PLCC footprint constraints |
Compared with SCC2681TC1A44, the SCC2692AC1A44 offers higher robustness and broader operating range but retains identical register mapping and pinout; the TL16C2550IPM delivers greater throughput via FIFOs and standardized interface logic but requires PCB redesign due to different package and signaling.
Availability
SCC2681TC1A44 is available at Aetrix Electronics and suitable for industrial terminal controllers, legacy POS system interfaces, telecom line card management, and embedded test equipment requiring stable component supply and long-lifecycle support.
Supply support for SCC2681TC1A44 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
NXP Semiconductors (formerly Philips Semiconductors) is a global leader in high-performance mixed-signal ICs, with expertise in connectivity, security, and automotive electronics.
The SCC2681 product line was developed to provide robust, programmable dual UART solutions for industrial and telecom infrastructure where deterministic timing, flexible framing, and integrated I/O are required - bridging legacy microprocessor buses to asynchronous serial peripherals.
FAQ
What is the maximum crystal frequency supported by the SCC2681TC1A44?
The SCC2681TC1A44 supports crystal frequencies from 2 MHz to 4 MHz on the X1/CLK and X2 pins, with typical operation at 3.6864 MHz for standard baud rate generation. The device's internal oscillator circuitry is designed specifically for fundamental-mode parallel-resonant crystals with load capacitance between 12 pF and 32 pF - exceeding this range may cause startup failure or frequency drift in the SCC2681TC1A44.
Does the SCC2681TC1A44 support automatic hardware flow control?
Yes, the SCC2681TC1A44 supports automatic RTS/CTS flow control through its programmable output port (OP0/OP1) and input port (IP0/IP1). When configured in RTS/CTS mode, OP0 asserts active-low RTSAN in response to receiver buffer fill level, and IP0 monitors CTSAN to gate transmitter output - all handled in hardware without CPU intervention, ensuring real-time responsiveness in the SCC2681TC1A44.
Can the SCC2681TC1A44 generate non-standard baud rates?
Yes, the SCC2681TC1A44 can generate non-standard baud rates using its 16-bit programmable counter/timer. By loading custom divisor values into the timer registers, designers can achieve precise bit rates not found in the 22 fixed-rate table - including fractional rates down to 1 bps resolution - making the SCC2681TC1A44 suitable for proprietary protocols requiring exact timing alignment.
What is the function of the "n.c." pins on the SCC2681TC1A44 PLCC package?
The SCC2681TC1A44 has four no-connect (n.c.) pins: pins 1, 12, 23, and 34. These pins are internally unconnected and must remain unattached in the PCB layout - neither tied to VCC, GND, nor routed. Leaving them floating is electrically safe; however, grounding them may introduce noise coupling or unintended parasitic paths that degrade signal integrity in the SCC2681TC1A44's sensitive clock and serial I/O sections.
How does the SCC2681TC1A44 handle break detection and generation?
The SCC2681TC1A44 provides hardware-level break detection on both RxDA and RxDB inputs, identifying prolonged low states (>1 character time) and asserting corresponding status bits (SRA[3]/SRB[3]). It also supports break generation via software command - forcing the transmitter into continuous space condition - with dedicated start-end break interrupt/status flags to synchronize host response in the SCC2681TC1A44.
SCC2681TC1A44,512 Specifications
- Product attributes
- Attribute value
- Manufacturer:
- NXP Semiconductors
- Package/Case:
- 44-LCC (J-Lead)
- Series:
- -
- Packaging:
- Tube
- Product Status:
- Obsolete
- Features:
- Configurable GPIO, Internal Oscillator, Timer/Counter
- Number of Channels:
- 2, DUART
- FIFO's:
- -
- Protocol:
- -
- Data Rate (Max):
- 1Mbps
- Voltage - Supply:
- 5V
- With Auto Flow Control:
- Yes
- With IrDA Encoder/Decoder:
- -
- With False Start Bit Detection:
- Yes
- With Modem Control:
- -
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 44-PLCC (16.59x16.59)
SCC2681TC1A44,512 FAQ
1.How can I place an order for SCC2681TC1A44,512 through Aetrix?
Please submit a Request for Quotation (RFQ) for SCC2681TC1A44,512 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 SCC2681TC1A44,512 reliable?
The price and inventory of SCC2681TC1A44,512 are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for SCC2681TC1A44,512 is usually 5 days.
3.What payment methods are accepted for SCC2681TC1A44,512?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for SCC2681TC1A44,512 transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for SCC2681TC1A44,512?
SCC2681TC1A44,512 orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your SCC2681TC1A44,512 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 SCC2681TC1A44,512?
For technical support, including SCC2681TC1A44,512 datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your SCC2681TC1A44,512 requirements.
6.How does Aetrix verify that SCC2681TC1A44,512 is sourced from the original manufacturer or authorized distributors?
All SCC2681TC1A44,512 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 SCC2681TC1A44,512 meets industry standards.
7.What is the process for return or replacement of SCC2681TC1A44,512?
All SCC2681TC1A44,512 units undergo pre-shipment inspection (PSI). If there is an issue with SCC2681TC1A44,512, 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 SCC2681TC1A44,512 part is unused and in its original packaging.
Return procedure for SCC2681TC1A44,512:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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