NXP Semiconductors SCC2691AE1N24,602

Overview

SCC2691AE1N24 from NXP Semiconductors (formerly Philips Semiconductors) is a CMOS-LSI universal asynchronous receiver/transmitter (UART) providing full-duplex serial communication with quadruple-buffered receiver, independent receiver/transmitter baud rate selection, and integrated 16-bit counter/timer. It operates from a single +5 V supply, supports 5–8 data bits with parity, and targets industrial embedded systems requiring reliable RS-232/RS-422 interface control in -40°C to +85°C environments.

For engineers reviewing the SCC2691AE1N24 datasheet, SCC2691AE1N24 pinout, SCC2691AE1N24 application, or SCC2691AE1N24 equivalent, key selection criteria include its 24-pin DIP package, TTL-compatible I/O, programmable channel modes (normal, loopback, echo), and dual-speed capability for clustered terminal or multi-processor wake-up applications.

Technical Context

The SCC2691AE1N24 implements a fully synchronous UART architecture with independent clock selectors for receiver and transmitter paths, enabling simultaneous operation at different baud rates-e.g., 9600 baud on Rx and 115.2 kbaud on Tx. Its internal crystal oscillator accepts 3.6864 MHz input, and the 16-bit counter/timer can generate custom 1X/16X clocks or serve as an external timing source routed to MPO.

Receiver logic includes false start bit detection, line break generation/detection, and a 3-deep FIFO with status-strobed parity/framing/overrun error bits. Transmitter supports automatic break generation, start/stop bit insertion, and TxRDY signaling via open-drain MPO output-critical for flow-controlled legacy serial subsystems.

Key Specifications

Pinout & Package

SCC2691AE1N24 is housed in a 24-pin plastic DIP (SOT222–1) with 0.600" body width and standard 0.300" row spacing. Pin 1 is RDN (Read Strobe), pin 24 is VCC, and pin 12 is GND. All digital I/O pins are TTL-compatible with 3-state bus drivers enabled by CEN.

Key Features

Applications

Equivalent & Alternatives

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

Compared with SCC2692AE1N24, the SCC2691AE1N24 offers lower gate count and reduced power for single-link applications, while TL16C550CP provides higher FIFO depth at the expense of missing critical features like independent Rx/Tx clocking and hardware flow control integration.

Availability

SCC2691AE1N24 is available at Aetrix Electronics and suitable for industrial serial gateways, legacy terminal controllers, multi-processor wake-up systems, and embedded modem interfaces requiring stable component supply across extended temperature ranges and long production lifecycles.

Supply support for SCC2691AE1N24 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 company formed from the spin-off of Philips Semiconductors in 2006, specializing in secure connectivity solutions for automotive, industrial, and IoT markets.

The SCC2691AE1N24 belongs to NXP's legacy communications IC portfolio, designed specifically for robust, low-power asynchronous serial interfacing in industrial control and embedded systems where long-term availability and deterministic timing behavior are critical.

FAQ

What is the maximum baud rate supported by the SCC2691AE1N24?

The SCC2691AE1N24 supports up to 115.2 kbaud using its internal baud rate generator or external clock inputs. When driven by a 3.6864 MHz crystal, it achieves this rate via 16X oversampling. Non-standard rates up to 115.2 kbaud are also achievable using the programmable 16-bit counter/timer, making the SCC2691AE1N24 suitable for both standard and proprietary serial protocols.

Does the SCC2691AE1N24 require an external crystal, or can it use an external clock signal?

The SCC2691AE1N24 supports both configurations: a 3.6864 MHz crystal connected between X1/CLK and X2, or an external clock signal applied directly to X1/CLK. If using an external clock, X2 may be left unconnected or grounded. The device accepts clock frequencies from 0 to 4.0 MHz, and all internal timing-including baud generation and counter/timer operation-derives from this source.

How does the receiver FIFO in the SCC2691AE1N24 prevent data overrun?

The SCC2691AE1N24 features a 3-character deep FIFO with dedicated FFULL and RxRDY status bits. When the FIFO fills, the MPO pin can be configured as RxRDY/FFULL to assert flow control (e.g., deassert RTSN), halting remote transmission. This hardware handshaking, combined with quadruple buffering and false start bit rejection, ensures zero data loss even under high-interrupt-latency conditions-critical for real-time industrial serial links.

Can the SCC2691AE1N24 operate in low-power mode while preserving register contents?

Yes-the SCC2691AE1N24 includes a dedicated power-down mode where the internal oscillator is frozen but all configuration registers (MR1/MR2, CSR, IMR, etc.) retain their values. Current drops to ≤500 µA, enabling rapid wake-up without reinitialization. This mode is activated via software command and is fully supported across the -40°C to +85°C industrial temperature range of the SCC2691AE1N24.

What are the key differences between the SCC2691AE1N24 and the TL16C550CP?

The SCC2691AE1N24 offers independent Rx/Tx baud rate selection, integrated 16-bit counter/timer, multi-processor address recognition, and hardware RTS/CTS flow control via MPO/MPI-features absent in the TL16C550CP. In contrast, the TL16C550CP provides a larger 16-byte FIFO but lacks the SCC2691AE1N24's dual-speed capability and advanced timing flexibility, making it better suited for basic PC COM port emulation than industrial protocol bridging.