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NXP Semiconductors SCC2681AC1A44,518
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- Part No.:
- SCC2681AC1A44,518
- Manufacturer:
- NXP Semiconductors
- Package:
- 44-LCC (J-Lead)
- Datasheet:
-
SCC2681AC1A44,518.pdf
- Description:
- IC DUART 1MBPS 44PLCC
- Quantity:
- Payment:
- Shipping:
Inventory:2,902
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Product details
Overview
SCC2681AC1A44,518 from NXP Semiconductors (formerly Philips) is a dual-channel CMOS asynchronous receiver/transmitter (DUART) providing two independent full-duplex UART channels in a 44-pin PLCC package. It supports programmable data formats (5–8 data bits, odd/even/no parity, 1/1.5/2 stop bits), 18 fixed baud rates up to 115.2 kbaud, and independent Rx/Tx clocking - used in industrial serial communication gateways requiring legacy RS-232/422 interface consolidation.
For engineers reviewing the SCC2681AC1A44,518 datasheet, SCC2681AC1A44,518 pinout, SCC2681AC1A44,518 application, or SCC2681AC1A44,518 equivalent, key selection considerations include its quadruple-buffered receivers for low-interrupt-overhead polling, 7-bit input port with change-of-state detection, 8-bit output port with individual bit set/reset, on-chip crystal oscillator, and support for automatic RS-485 turn-around via OP0/OP1.
Technical Context
The SCC2681AC1A44,518 implements two independent UART channels sharing a single 8-bit bidirectional data bus (D0–D7), address decoding (A0–A3), and chip enable (CEN) logic. Each channel features separate mode registers (MR1A/MR2A, MR1B/MR2B), status registers (SRA/SRB), and command registers (CRA/CRB), enabling asymmetric configuration - e.g., Channel A at 9600 baud with 8N1 and hardware flow control, Channel B at 38.4 kbaud with 7E2 and local loopback.
Its timing subsystem integrates a 3.6864 MHz on-chip crystal oscillator (X1/CLK + X2), a 16-bit programmable counter/timer, and four clock selectors that route either BRG-derived 16× clocks, timer outputs, or external 1×/16× signals independently to each Rx/Tx path. The interrupt system uses a single active-low open-drain INTRN output with eight maskable sources and optional discrete wire-ORable outputs on OP3–OP7.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Function | Dual full-duplex asynchronous receiver/transmitter (DUART) with independent channel control |
| Supply Voltage | +5 V ± 5% (commercial grade); enables direct interfacing with 5 V microcontrollers without level-shifting |
| Baud Rate Range | 50 to 115.2 kbaud via 18 fixed rates or user-defined rate from 16-bit counter/timer - supports non-standard legacy protocols |
| Data Format | Programmable per channel: 5–8 data bits, odd/even/no/force parity, 1/1.5/2 stop bits in 1/16-bit increments - accommodates diverse host and peripheral framing |
| Receiver Buffering | Quadruple-buffered RHR per channel - reduces CPU polling frequency and prevents overrun in burst-mode reception |
| Interrupt Architecture | Single INTRN output with eight maskable sources plus six configurable discrete interrupt outputs (OP3–OP7) - enables flexible priority handling in multi-interrupt systems |
| Input Port | 7-bit multipurpose input port (IP0–IP6) with internal 1–4 µA pull-ups and change-of-state detection on IP0–IP3 - eliminates external debounce circuitry for control signal monitoring |
| Output Port | 8-bit multipurpose output port (OP0–OP7) with individual bit set/reset (addresses 0xE/0xF) and auto RS-485 turn-around capability - simplifies half-duplex bus control without external logic |
Pinout & Package
SCC2681AC1A44,518 is housed in a 44-pin plastic leaded chip carrier (PLCC) package (SOT187-2), 16.5 mm × 16.5 mm, with J-lead geometry suitable for surface-mount reflow assembly and socket-based prototyping.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| D0–D7 | Bidirectional data bus | 3-state interface to 8-bit CPU/data bus; D0 = LSB; enables register read/write and status access |
| A0–A3 | Address inputs | Selects one of 16 internal registers (e.g., MR1A=0x00, THR=0x04, SR=0x06) for access via D0–D7 |
| CEN | Chip enable | Active-low enable for data transfers; places D0–D7 in high-impedance state when deasserted |
| RDN / WRN | Read / write strobes | Edge-triggered controls: RDN falling edge initiates read; WRN rising edge latches write data |
| RxDA / RxDB | Channel A/B receiver inputs | CMOS-level serial inputs; accept mark (HIGH)/space (LOW) logic; sampled at 16× or 1× clock |
| TxDA / TxDB | Channel A/B transmitter outputs | CMOS-level serial outputs; hold HIGH (mark) when idle or disabled; support break generation |
| INTRN | Interrupt request | Open-drain, active-low output; asserts when any unmasked interrupt condition occurs (e.g., RxRDY, TxRDY) |
| X1/CLK / X2 | Clock inputs | Crystal oscillator terminals (3.6864 MHz typical); X1 accepts external clock if crystal omitted |
| OP0–OP7 | Configurable output port | Individually programmable as GPIO, RTS/CTS, Tx/Rx ready, DMA, or counter/timer interrupts |
| IP0–IP6 | Configurable input port | General-purpose inputs with internal pull-ups; IP0–IP3 support change-of-state interrupt detection |
| RESET | Hardware reset | Active-high signal clearing all registers, stopping timer, and forcing Tx outputs to mark state |
| VCC / GND | Power supply | +5 V ± 5% supply and ground reference; decoupling required per datasheet layout guidelines |
Key Features
| Feature | Design Value |
|---|---|
| Independent Rx/Tx clocking per channel | Enables dual-speed operation - e.g., Channel A at 19.2 kbaud for modem control, Channel B at 115.2 kbaud for sensor telemetry |
| Quadruple receiver buffering | Reduces interrupt service overhead by 75% vs. single-buffer UARTs in high-throughput polled systems |
| Auto RS-485 turn-around on OP0/OP1 | Eliminates external transceiver direction-control logic; automatically toggles RTSN after last bit transmission |
| Change-of-state detection on IP0–IP3 | Hardware-accelerated edge detection (min. 25 µs pulse width) avoids software polling for switch/button inputs |
| 16-bit programmable counter/timer | Generates precise time delays, square waves, or timeout events - used for custom baud rate synthesis or watchdog functions |
| False start bit and line break detection | Improves robustness in noisy industrial environments by rejecting spurious transitions and supporting break signaling for remote reset |
Applications
| Industrial Serial Gateway | Legacy Terminal Server |
|---|---|
Use Scenario: Aggregating Modbus RTU, ASCII, and proprietary serial sensors into a single Ethernet-connected controller. IC Role / Device Role / Timing Role: DUART provides dual isolated UART interfaces with independent baud rates, flow control, and hardware RTS/CTS handshaking. Use Value: Quadruple buffering prevents data loss during burst transmissions from multiple field devices; auto RS-485 turn-around ensures reliable half-duplex bus arbitration. | Use Scenario: Connecting multiple dumb terminals (e.g., VT100, Wyse 50) to a central host via clustered multidrop lines. IC Role / Device Role / Timing Role: DUART operates in automatic wake-up mode with start-end break detection to selectively activate terminal channels. Use Value: Independent receiver/transmitter clocking allows mixed-speed terminal support; false start bit rejection improves reliability over long cable runs. |
| Medical Device Communication Hub | Avionics Data Concentrator |
Use Scenario: Interfacing ECG monitors, infusion pumps, and patient IDs to a central nursing station using RS-232/422 links. IC Role / Device Role / Timing Role: DUART serves as a deterministic serial bridge with programmable parity and stop bits to match diverse medical equipment framing. Use Value: On-chip crystal oscillator eliminates external timing components; 7-bit input port monitors device-ready signals with change-of-state interrupts. | Use Scenario: Consolidating ARINC 429, MIL-STD-1553, and RS-422 avionics subsystems onto a common flight management unit backplane. IC Role / Device Role / Timing Role: DUART handles asynchronous maintenance and diagnostic channels with strict error detection (parity, framing, overrun). Use Value: Line break generation and detection enable remote reset and synchronization; industrial temperature range (–40 °C to +85 °C) meets DO-160 environmental requirements. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar dual UART applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| SCC2692AC1A44 | Enhanced version with 16-byte FIFOs per channel, higher max baud (230.4 kbaud), and extended interrupt vectoring | Required for high-throughput applications where SCC2681AC1A44,518's quadruple buffering is insufficient | Select only if FIFO depth >4 and baud >115.2 kbaud are mandatory; not pin-compatible due to register map changes |
| TL16C550CPTR | Industry-standard 16550-compatible UART with 16-byte FIFO, but single-channel; requires two units for dual functionality | Suitable for PC-compatible designs where BIOS/driver support for 16550 is already established | Choose when leveraging existing 16550 software stack; adds board area and routing complexity vs. single-chip SCC2681AC1A44,518 |
Compared with SCC2681AC1A44,518, the SCC2692AC1A44 offers deeper buffering and faster rates but sacrifices register compatibility, while the TL16C550CPTR delivers proven driver support at the cost of component count and PCB footprint - making SCC2681AC1A44,518 optimal for space-constrained, cost-sensitive embedded systems needing integrated dual-channel control.
Availability
SCC2681AC1A44,518 is available at Aetrix Electronics and suitable for industrial serial gateways, legacy terminal servers, medical device communication hubs, and avionics data concentrators requiring stable component supply across extended product lifecycles.
Supply support for SCC2681AC1A44,518 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 is a global semiconductor leader focused on secure connectivity solutions for automotive, industrial, and IoT applications.
The SCC2681AC1A44,518 belongs to NXP's legacy communications IC portfolio, designed specifically for robust, low-power dual-channel serial interface consolidation in mission-critical embedded systems operating across commercial and industrial temperature ranges.
FAQ
What is the maximum supported baud rate for SCC2681AC1A44,518?
The SCC2681AC1A44,518 supports a maximum baud rate of 115.2 kbaud using its internal 18-rate baud generator. When configured with the 16-bit counter/timer and a 3.6864 MHz crystal, it can synthesize non-standard rates up to 115.2 kbaud. External 1× or 16× clock inputs allow operation beyond this limit, but the datasheet specifies 115.2 kbaud as the highest characterized fixed rate. The SCC2681AC1A44,518 does not support rates above 115.2 kbaud in standard configurations.
Does SCC2681AC1A44,518 include an on-chip crystal oscillator?
Yes, the SCC2681AC1A44,518 integrates a CMOS crystal oscillator circuit between pins X1/CLK and X2. A 3.6864 MHz crystal is recommended for standard baud rate generation, though frequencies from 1.0 to 4.0 MHz are supported. If an external clock is preferred, it may be applied to X1/CLK while leaving X2 unconnected - the SCC2681AC1A44,518 will use that signal as its master timing reference.
How does the SCC2681AC1A44,518 handle RS-485 half-duplex bus control?
The SCC2681AC1A44,518 supports automatic RS-485 turn-around via its OP0 and OP1 outputs. When configured in "auto 485 turn-around" mode, the device asserts OP0 (for Channel A) or OP1 (for Channel B) as RTSN during transmission and deasserts it one bit time after the final stop bit - eliminating need for external direction-control logic. This function is enabled through the Output Port Configuration Register (OPCR) and requires no CPU intervention during data transfer.
Can SCC2681AC1A44,518 operate with different data formats on each channel?
Yes, the SCC2681AC1A44,518 allows fully independent programming of data format per channel. Channel A and Channel B each have dedicated Mode Registers (MR1A/MR2A and MR1B/MR2B) controlling data bits (5–8), parity type (odd/even/no/force), and stop bits (1/1.5/2 in 1/16-bit increments). This enables simultaneous operation - for example, Channel A using 7E1 for legacy printer interface and Channel B using 8N2 for modern sensor telemetry - without shared configuration constraints.
What is the purpose of the 7-bit input port (IP0–IP6) on SCC2681AC1A44,518?
The 7-bit input port (IP0–IP6) on the SCC2681AC1A44,518 serves dual roles: general-purpose digital inputs or dedicated auxiliary signals. IP0–IP3 support hardware change-of-state detection with interrupt capability; IP2 doubles as counter/timer external clock input; IP3/IP4/IP5/IP6 serve as external clock inputs for Channel A/B receivers/transmitters. All pins feature internal 1–4 µA pull-ups, allowing direct connection of switches or open-collector signals without external resistors. The SCC2681AC1A44,518 reads this port at address 0xD.
SCC2681AC1A44,518 Specifications
- Product attributes
- Attribute value
- Manufacturer:
- NXP Semiconductors
- Package/Case:
- 44-LCC (J-Lead)
- Series:
- -
- Packaging:
- Tape & Reel (TR)
- 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)
SCC2681AC1A44,518 FAQ
1.How can I place an order for SCC2681AC1A44,518 through Aetrix?
Please submit a Request for Quotation (RFQ) for SCC2681AC1A44,518 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 SCC2681AC1A44,518 reliable?
The price and inventory of SCC2681AC1A44,518 are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for SCC2681AC1A44,518 is usually 5 days.
3.What payment methods are accepted for SCC2681AC1A44,518?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for SCC2681AC1A44,518 transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for SCC2681AC1A44,518?
SCC2681AC1A44,518 orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your SCC2681AC1A44,518 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 SCC2681AC1A44,518?
For technical support, including SCC2681AC1A44,518 datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your SCC2681AC1A44,518 requirements.
6.How does Aetrix verify that SCC2681AC1A44,518 is sourced from the original manufacturer or authorized distributors?
All SCC2681AC1A44,518 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 SCC2681AC1A44,518 meets industry standards.
7.What is the process for return or replacement of SCC2681AC1A44,518?
All SCC2681AC1A44,518 units undergo pre-shipment inspection (PSI). If there is an issue with SCC2681AC1A44,518, 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 SCC2681AC1A44,518 part is unused and in its original packaging.
Return procedure for SCC2681AC1A44,518:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
SCC2681AC1A44,518 Tags
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