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NXP Semiconductors SCC2681AC1A44,512
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- Part No.:
- SCC2681AC1A44,512
- Manufacturer:
- NXP Semiconductors
- Package:
- 44-LCC (J-Lead)
- Datasheet:
-
SCC2681AC1A44,512.pdf
- Description:
- IC UART 44-PLCC
- Quantity:
- Payment:
- Shipping:
Inventory:4,083
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Product details
Overview
SCC2681AC1A44,512 from NXP Semiconductors (formerly Philips) is a dual-channel CMOS universal asynchronous receiver/transmitter (DUART) in 44-pin PLCC package, supporting independent full-duplex serial communication on Channels A and B with quadruple-buffered receivers, programmable 5–8-bit data format, 1–2 stop bits, odd/even/no parity, and up to 115.2 kbaud via internal baud rate generator or external clock. It operates from a single +5 V supply and targets industrial embedded serial interface applications.
For engineers reviewing the SCC2681AC1A44,512 datasheet, SCC2681AC1A44,512 pinout, SCC2681AC1A44,512 application, or SCC2681AC1A44,512 equivalent, key selection considerations include independent channel baud rate configuration, 7-bit input/8-bit output port flexibility, crystal oscillator integration, open-drain interrupt outputs (INTRN, OP3–OP7), and support for automatic RTS/CTS flow control in multidrop systems.
Technical Context
The SCC2681AC1A44,512 implements two independent UART channels sharing a common 8-bit bidirectional data bus (D0–D7), address decoding (A0–A3), and chip enable (CEN) logic. Each channel features separate receiver and transmitter clock selectors, enabling simultaneous operation at different baud rates - e.g., Channel A at 9600 baud (16× clock) and Channel B at 19200 baud (external 1× clock).
Its timing subsystem integrates an on-chip crystal oscillator (X1/CLK, X2), a 16-bit programmable counter/timer, and four clock selectors that route timing sources to individual Rx/Tx blocks. The receiver uses 16× oversampling for start-bit detection and bit-center sampling, while the transmitter supports break generation, false-start rejection, and line-break detection with status flag reporting in SRA/SRB registers.
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 compatibility with legacy 5 V microprocessor buses |
| Max Baud Rate | 115.2 kbaud per channel; achieved using internal 16× clock derived from 3.6864 MHz crystal or external source |
| Data Format | 5–8 data bits, 1/1.5/2 stop bits (in 1/16-bit increments), odd/even/no/force parity; fully software-configurable per channel |
| Receiver Buffering | Quadruple-buffered RHR per channel; reduces CPU interrupt overhead and prevents overrun in high-throughput polling or interrupt-driven systems |
| Interrupt Architecture | Single active-low INTRN output with eight maskable conditions; plus six wire-ORable open-drain outputs (OP3–OP7) for discrete TxRDY/RxRDY/CT interrupts |
| Package | PLCC44 (SOT187-2); 16.5 mm × 16.5 mm body, J-lead, surface-mount compatible with industrial reflow profiles |
Pinout & Package
SCC2681AC1A44,512 is housed in a 44-pin plastic leaded chip carrier (PLCC, SOT187-2) with index corner marking. The package supports surface-mount assembly and provides thermal performance suitable for industrial ambient temperatures (0 °C to +70 °C).
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1, 12, 23, 34 | NC | No-connect pins; must remain unconnected per datasheet to avoid signal integrity or latch-up risk |
| D0–D7 (Pins 18, 19, 20, 21, 25, 26, 27, 28) | Data Bus I/O | Bidirectional 3-state bus for register access; D0 = LSB; requires external pull-ups if used in open-bus configurations |
| A0–A3 (Pins 2, 4, 6, 7) | Address Inputs | Select internal registers (e.g., MR1A=0x00, THR=0x04); decoded internally to 16 addressable locations |
| CEN (Pin 39) | Chip Enable | Active-low enable for data bus transactions; when HIGH, places D0–D7 in high-impedance state |
| WRN (Pin 9), RDN (Pin 10) | Write/Read Strobe | Edge-triggered controls: WRN rising edge latches data; RDN falling edge initiates read; both require CEN LOW |
| RxDA (Pin 35), RxDB (Pin 11) | Channel A/B Receiver Input | CMOS-level serial inputs; "mark" = HIGH, "space" = LOW; accept 16× oversampled or 1× clocked data |
| TxDA (Pin 33), TxDB (Pin 13) | Channel A/B Transmitter Output | Push-pull outputs held HIGH (mark) when idle; support break generation and auto-RTS deactivation |
| INTRN (Pin 24) | Interrupt Request | Open-drain, active-low output; asserts when any of eight maskable conditions occur (e.g., RxRDY, TxRDY, CTS change) |
| X1/CLK (Pin 36), X2 (Pin 37) | Clock Input/Output | Crystal connection points for 3.6864 MHz fundamental-mode crystal; X1 accepts external clock up to 4.0 MHz |
| RESET (Pin 38) | Hardware Reset | Active-high synchronous reset; clears SRA/SRB/IMR/ISR/OPR and halts counter/timer; initializes MR pointer to MR1 |
| VCC (Pin 44), GND (Pin 22) | Power Supply | +5 V ± 5% supply with decoupling recommended within 10 mm; GND plane required for noise immunity |
Key Features
| Feature | Design Value |
|---|---|
| Independent Rx/Tx clock selection | Each channel selects timing from 18 fixed baud rates, 16-bit counter/timer, or external 1×/16× clock - enabling dual-speed terminal clustering |
| Flow control with RTS/CTS | OP0/OP1 programmable as active-low RTSAN/RTSBN; IP0/IP1 as active-low CTSAN/CTSBN; hardware handshaking reduces buffer overflow risk |
| Multipurpose I/O ports | 7-bit input port (IP0–IP6) with change-of-state detection on IP0–IP3; 8-bit output port (OP0–OP7) with individual bit set/reset and function assignment |
| False start & break detection | Detects invalid start bits and mid-character breaks; flags in SRA/SRB with dedicated interrupt capability for robust protocol recovery |
| Automatic wake-up mode | Enables low-power multidrop bus monitoring: device wakes on valid address character after idle period, reducing system power in remote nodes |
Applications
| Industrial Serial Terminal Interface | Legacy Equipment Retrofit |
|---|---|
|
Use Scenario: Connecting PLCs, HMIs, and CNC controllers via RS-232/RS-422 physical layers in factory automation networks. IC Role / Device Role / Timing Role: DUART handles protocol framing, baud rate adaptation, and hardware flow control between microcontroller and line drivers. Use Value: Quadruple buffering and independent channel timing allow concurrent high-speed diagnostics (Channel A) and low-speed parameter updates (Channel B) without CPU contention. |
Use Scenario: Upgrading aging point-of-sale terminals or medical instruments with obsolete UARTs while retaining existing 5 V logic and PCB layout. IC Role / Device Role / Timing Role: Drop-in replacement for legacy dual UARTs (e.g., INS8250, Z8530) with identical PLCC44 footprint and register-compatible programming model. Use Value: Pin-for-pin compatibility with SOT187-2 land pattern and identical A0–A3 addressing simplifies redesign; +5 V operation avoids level-shifter redesign. |
| Multi-Protocol Communication Hub | Embedded Modem Control Interface |
|
Use Scenario: Managing simultaneous connections to GPS modules (TTL UART), barcode scanners (RS-232), and wireless transceivers (3.3 V logic with level shift) in fleet-tracking gateways. IC Role / Device Role / Timing Role: Central serial concentrator with configurable voltage thresholds, clock sourcing, and interrupt prioritization across heterogeneous peripherals. Use Value: Independent 1×/16× clock inputs per channel allow native TTL (1×) and RS-232 (16×) timing without external dividers; OP0–OP7 provide ready-made RTS/CTS/DTR signals. |
Use Scenario: Controlling dial-up modems in industrial telemetry units where AT command parsing, carrier detect, and ring indicator signaling are required. IC Role / Device Role / Timing Role: UART interface with precise break detection, line-status monitoring (DSR, DCD, RI), and auto-RTS assertion during transmission. Use Value: Built-in line-break interrupt and start-end break detection enable reliable modem hang-up detection; IP0–IP6 support DSR/DCD/RI inputs with change-of-state interrupt. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar dual UART applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| SCC2691AC1A44 | Successor with enhanced ESD rating (±4 kV HBM), extended temperature range (–40 °C to +85 °C), and improved AC timing margins; same PLCC44 pinout and register map | Required for new designs targeting industrial environments with higher reliability and wider thermal operating range | Select SCC2691AC1A44 when long-term availability, extended temperature compliance, or higher ESD robustness are mandatory |
| MAX3100EAP+ | SPI-interface dual UART with integrated RS-232 drivers; operates from +2.7 V to +5.5 V; no crystal oscillator; 28-pin SSOP package | Suitable for space-constrained, low-voltage, or SPI-based MCU platforms where parallel bus interface is unavailable | Choose MAX3100EAP+ only when migrating from parallel to SPI host interface or requiring integrated level translation |
Compared with SCC2681AC1A44,512, the SCC2691AC1A44 offers backward-compatible enhancements for harsher environments, while the MAX3100EAP+ trades parallel bus simplicity for SPI flexibility and integrated transceivers - neither is pin-compatible, but both serve overlapping dual-serial-channel use cases with distinct system-level trade-offs.
Availability
SCC2681AC1A44,512 is available at Aetrix Electronics and suitable for industrial automation, legacy equipment maintenance, and embedded communication hub designs requiring stable component supply, long-lifecycle support, and verified second-source alternatives.
Supply support for SCC2681AC1A44,512 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, headquartered in Eindhoven, Netherlands, develops high-performance analog and mixed-signal ICs for automotive, industrial, and IoT applications, with heritage from Philips Semiconductor's communications product line.
The SCC2681AC1A44,512 belongs to NXP's legacy communications interface portfolio, designed specifically for robust, low-power, parallel-bus-connected serial bridging in industrial control, instrumentation, and retrofit systems requiring deterministic timing and long-term obsolescence resilience.
FAQ
What is the maximum supported crystal frequency for SCC2681AC1A44,512?
The SCC2681AC1A44,512 supports a nominal crystal frequency of 3.6864 MHz, with specified operation from 1.0 MHz to 4.0 MHz per the AC characteristics table. Frequencies outside this range are not characterized, and operation below 1.0 MHz is not guaranteed - the device requires continuous clocking at X1/CLK for all functional blocks including the baud rate generator and counter/timer. SCC2681AC1A44,512 must be operated within these limits to ensure timing compliance and error-free serial communication.
Does SCC2681AC1A44,512 support RS-485 half-duplex auto-turnaround?
Yes, SCC2681AC1A44,512 supports RS-485 auto-turnaround via OP0 and OP1 outputs, which can be programmed as RTSAN and RTSBN signals with automatic deactivation after transmission completes. When configured in auto-turnaround mode, the output toggles based on TxRDY status and channel enable state, eliminating need for external logic. This feature is documented in the Output Port section and applies directly to SCC2681AC1A44,512 in PLCC44 configuration.
Can SCC2681AC1A44,512 operate with separate clocks for receiver and transmitter on the same channel?
Yes, SCC2681AC1A44,512 allows independent clock selection for each receiver and transmitter via its four clock selectors - for example, Channel A receiver may use the internal 16× baud rate generator while Channel A transmitter uses an external 1× clock applied to IP3. This capability is explicitly stated in the DESCRIPTION and FEATURES sections and confirmed in the Clock Selectors block of the block diagram, making SCC2681AC1A44,512 suitable for asymmetric-rate protocols like multidrop addressing.
What is the purpose of the 7-bit input port (IP0–IP6) on SCC2681AC1A44,512?
The 7-bit input port (IP0–IP6) on SCC2681AC1A44,512 serves dual roles: as general-purpose digital inputs readable at address 0xD, or as dedicated control signals including CTSAN (IP0), CTSBN (IP1), external timer clock (IP2), and external Tx/Rx clocks (IP3–IP6). Four pins (IP0–IP3) support change-of-state detection with interrupt capability, and all include 1–4 µA internal pull-ups - eliminating need for external resistors unless stronger drive is required. This functionality is integral to SCC2681AC1A44,512's flexible peripheral interfacing.
Is SCC2681AC1A44,512 compatible with modern 3.3 V microcontrollers?
SCC2681AC1A44,512 is a +5 V-only device with TTL/CMOS input thresholds (VIH = 2.0 V min at 0 °C) and push-pull outputs driving to VCC. Direct connection to 3.3 V MCUs requires level translation on D0–D7, A0–A3, WRN, RDN, and CEN lines to prevent overvoltage damage and ensure logic-level compatibility. While SCC2681AC1A44,512 interfaces electrically with 3.3 V systems using external buffers, it does not support native 3.3 V operation - its core design targets legacy 5 V embedded platforms.
SCC2681AC1A44,512 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)
SCC2681AC1A44,512 FAQ
1.How can I place an order for SCC2681AC1A44,512 through Aetrix?
Please submit a Request for Quotation (RFQ) for SCC2681AC1A44,512 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 SCC2681AC1A44,512 reliable?
The price and inventory of SCC2681AC1A44,512 are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for SCC2681AC1A44,512 is usually 5 days.
3.What payment methods are accepted for SCC2681AC1A44,512?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for SCC2681AC1A44,512 transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for SCC2681AC1A44,512?
SCC2681AC1A44,512 orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your SCC2681AC1A44,512 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 SCC2681AC1A44,512?
For technical support, including SCC2681AC1A44,512 datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your SCC2681AC1A44,512 requirements.
6.How does Aetrix verify that SCC2681AC1A44,512 is sourced from the original manufacturer or authorized distributors?
All SCC2681AC1A44,512 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 SCC2681AC1A44,512 meets industry standards.
7.What is the process for return or replacement of SCC2681AC1A44,512?
All SCC2681AC1A44,512 units undergo pre-shipment inspection (PSI). If there is an issue with SCC2681AC1A44,512, 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 SCC2681AC1A44,512 part is unused and in its original packaging.
Return procedure for SCC2681AC1A44,512:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
SCC2681AC1A44,512 Tags
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NXP Semiconductors
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