NXP Semiconductors SCC68681C1A44,512

Overview

SCC68681C1A44,512 from NXP Semiconductors (formerly Philips Semiconductors) is a dual-channel CMOS universal asynchronous receiver/transmitter (DUART) providing two independent full-duplex serial communication channels in a single PLCC44 package. It supports programmable data formats (5–8 data bits, odd/even/no parity, 1/1.5/2 stop bits), independent baud rate selection per channel (up to 115.2 kbaud), and quadruple-buffered receivers for robust UART operation in industrial control and legacy embedded systems.

For engineers reviewing the SCC68681C1A44,512 datasheet, SCC68681C1A44,512 pinout, SCC68681C1A44,512 application, or SCC68681C1A44,512 equivalent, key selection considerations include its S68000 bus compatibility, 16-bit programmable counter/timer, dual-channel interrupt management via INTRN and configurable OPx outputs, and support for multidrop wake-up mode with address/data tagging.

Technical Context

The SCC68681C1A44,512 implements two independent UART channels (A and B), each with fully programmable transmitter and receiver timing-enabling asymmetric baud rates (e.g., Rx at 9600 bps, Tx at 19200 bps). Its internal 16× clock architecture samples incoming data at 16× the bit rate for precise start-bit detection and center-sampling of data bits.

It integrates a 16-bit programmable counter/timer operating in timer, counter, or timeout modes; a 6-bit input port with change-of-state detection on four pins; and an 8-bit output port supporting individual bit set/reset and auto RS-485 turn-around control. All registers are memory-mapped via A1–A4 address lines and accessed over an 8-bit bidirectional data bus (D0–D7).

Key Specifications

Pinout & Package

SCC68681C1A44,512 is housed in a 44-pin PLCC (SOT187-2) package with gull-wing leads, designed for high-reliability industrial PCB mounting. Pin 44 is VCC (+5 V), pin 22 is GND, and pin 38 is active-low RESETN.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar dual UART applications.

Compared with SCC68681C1A44,512, the SCC68681C1N40 offers identical functionality in a less rugged package, while the TL16C550CIPN sacrifices dual-channel integration and advanced timing features for higher FIFO depth-making SCC68681C1A44,512 optimal for space-constrained, protocol-diverse industrial designs requiring hardware-level UART coordination.

Availability

SCC68681C1A44,512 is available at Aetrix Electronics and suitable for industrial PLC communication, legacy terminal emulation, multidrop SCADA networks, and embedded modem interfaces requiring stable component supply and long-term obsolescence management.

Supply support for SCC68681C1A44,512 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 is a global semiconductor leader focused on secure connectivity solutions for automotive, industrial, and IoT applications, with roots in Philips' pioneering analog and mixed-signal IC development.

The SCC68681 product line was designed for high-reliability, bus-compatible serial communication in embedded control systems-targeting applications where deterministic timing, dual-channel independence, and legacy protocol support are critical.

FAQ

What is the maximum supported baud rate for each channel of the SCC68681C1A44,512?

The SCC68681C1A44,512 supports a maximum baud rate of 115.2 kbaud per channel. This is achieved using the internal baud rate generator with a 3.6864 MHz crystal reference. Non-standard rates up to this limit are also possible via the 16-bit programmable counter/timer or external 1×/16× clock inputs. The SCC68681C1A44,512 does not support rates beyond 115.2 kbaud in standard operation.

Does the SCC68681C1A44,512 support RS-485 half-duplex operation?

Yes, the SCC68681C1A44,512 supports hardware-controlled RS-485 half-duplex operation via its programmable output port. Specifically, OP0–OP7 can be configured for automatic transceiver direction control (auto turn-around), eliminating software timing dependencies. This feature is explicitly documented in the "Multi-function 8-bit output port" section of the datasheet and applies directly to the SCC68681C1A44,512.

How many characters can the receiver FIFO hold in the SCC68681C1A44,512?

The SCC68681C1A44,512 receiver implements a three-character deep FIFO stack (plus one character in the shift register), totaling quadruple buffering. When the FIFO is full, the FFULL status bit is asserted, and subsequent received characters overwrite the oldest un-read character-triggering an overrun error. This structure is confirmed in the "Receiver FIFO" section of the official product data sheet for the SCC68681C1A44,512.

Is the SCC68681C1A44,512 compatible with the Motorola 68000 family of microprocessors?

Yes, the SCC68681C1A44,512 is explicitly designed for S68000 bus compatibility and interfaces directly with Motorola 68000-series microprocessors. Its address decoding (A1–A4), control signals (R/WN, CSN, DTACKN), and timing align with the 68000's synchronous bus protocol. This compatibility is stated in the "DESCRIPTION" section of the official Philips/NXP datasheet for the SCC68681C1A44,512.

What is the function of the IP0–IP5 pins on the SCC68681C1A44,512?

The IP0–IP5 pins on the SCC68681C1A44,512 serve as a 6-bit multipurpose input port. They can operate as general-purpose digital inputs with internal ~2 µA pull-ups, or be assigned specific functions including CTS (clear-to-send), external clock inputs for receivers/transmitters, or counter/timer clock sources. Change-of-state detection is supported on IP0–IP3, enabling edge-triggered interrupts. These functions are defined in the "PIN DESCRIPTION" table for the SCC68681C1A44,512.