NXP Semiconductors SC28C94A1A,518

Overview

SC28C94A1A,518 from NXP Semiconductors (formerly Philips Semiconductors) is a quad universal asynchronous receiver/transmitter (QUART) integrating four independent UART channels with 8-byte receive and transmit FIFOs per channel, programmable 5–8 data bits + parity, 1/1.5/2 stop bits, and independent baud rate selection up to 1 Mbps for each receiver and transmitter. It operates from a single +5 V supply and supports industrial temperature range (–40 °C to +85 °C) in a 52-pin PLCC package, targeting multi-channel serial communication in industrial control and terminal systems.

For engineers reviewing the SC28C94A1A,518 datasheet, SC28C94A1A,518 pinout, SC28C94A1A,518 application, or SC28C94A1A,518 equivalent, key selection criteria include its 4-channel full-duplex UART architecture, 16-bit counter/timer per block, vectored interrupt support with priority arbitration, on-chip crystal oscillator, and power-down mode reducing consumption by several magnitudes.

Technical Context

The SC28C94A1A,518 implements four industry-standard UARTs organized into two independent blocks (A/B and C/D), each with dedicated 16-bit counter/timers, separate baud rate generators, and shared global interrupt logic. Its timing architecture supports simultaneous use of internal crystal (3.6864 MHz or 7.3728 MHz), external clock (≤8 MHz), or programmable counter/timer outputs for receiver/transmitter clocking.

Each UART features hardware handshaking (RTS control), false start bit detection, line break generation/detection, and a "watch dog" timer per receiver. The interrupt system provides vectored responses with programmable vector format, IACKN/DTACKN handshake signals, and identification of highest-priority active interrupt via the Current Interrupt Register (CIR).

Key Specifications

Pinout & Package

SC28C94A1A,518 is housed in a 52-pin Plastic Leaded Chip Carrier (PLCC) package with gull-wing leads, designed for reflow soldering and high-pin-count density in industrial control modules.

Key Features

Applications

Equivalent & Alternatives

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

Compared with SC28C94A1A,518, the XR16L788IQ-F sacrifices +5 V compatibility and oscillator integration for transceiver integration, while the MAX3107ETJ+ abandons parallel bus timing for serial control and deeper FIFOs - neither replicates the SC28C94A1A,518's combination of industrial-grade +5 V operation, on-chip oscillator, power-down mode, and vectored interrupt architecture.

Availability

SC28C94A1A,518 is available at Aetrix Electronics and suitable for industrial serial gateways, clustered terminal systems, legacy equipment retrofits, and modem communication controllers requiring stable component supply, long-lifecycle support, and guaranteed availability through extended manufacturing programs.

Supply support for SC28C94A1A,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, with deep heritage in high-reliability mixed-signal ICs.

The SC28C94A1A,518 belongs to NXP's legacy industrial communications portfolio, designed specifically for robust, multi-channel asynchronous serial interfacing in harsh environments where long-term supply stability and deterministic interrupt response are critical.

FAQ

What is the maximum baud rate supported by SC28C94A1A,518?

The SC28C94A1A,518 supports up to 1 Mbps when using an external 1X or 16X clock input (≤8 MHz). With its internal crystal oscillator (3.6864 MHz or 7.3728 MHz), it delivers standard rates up to 230.4 kbaud and enhanced rates up to 500 kbaud via counter/timer configuration. The 16X clock mode ensures reliable sampling at high speeds by validating the start bit and centering samples within bit cells.

Does SC28C94A1A,518 include an on-chip oscillator?

Yes, SC28C94A1A,518 includes an on-chip crystal oscillator that operates directly from a 3.6864 MHz or 7.3728 MHz crystal connected between X1/CLK and X2 pins. When an external clock is used instead of a crystal, X1/CLK accepts frequencies up to 8 MHz and X2 is left unconnected. The oscillator serves as the timing reference for the baud rate generator, counter/timers, and internal logic.

How does the power-down mode function in SC28C94A1A,518?

In power-down mode, SC28C94A1A,518 stops the on-chip oscillator and retains all register contents and FIFO data while reducing power consumption by several orders of magnitude. The device exits power-down upon assertion of RESET or when CEN is activated with a valid read/write cycle. This mode is ideal for battery-powered or intermittently active serial nodes where low quiescent current is essential.

Can SC28C94A1A,518 operate with different baud rates for receiver and transmitter on the same channel?

Yes, SC28C94A1A,518 allows independent baud rate selection for the receiver and transmitter on each of its four UART channels. This is achieved via separate clock selectors in the Clock Select Register (CSR) for each channel, enabling dual-speed operation - for example, 9600 bps for host-to-terminal transmission and 19200 bps for terminal-to-host reception in clustered terminal systems.

What interrupt capabilities does SC28C94A1A,518 provide?

SC28C94A1A,518 provides vectored interrupts with programmable vector format, priority arbitration based on FIFO fill levels and event type, and identification of the highest-priority active interrupt via the Current Interrupt Register (CIR). It supports IACKN handshake, global interrupt registers, and individual maskable sources including Rx/Tx FIFO status, counter/timer timeout, line errors, and change-of-state detection - minimizing host polling overhead.