NXP Semiconductors SC28L194A1A,529

Overview

SC28L194A1A,529 from NXP Semiconductors (formerly Philips) is a quad-channel CMOS UART IC supporting both 3.3 V and 5.0 V single-supply operation. It integrates four independent full-duplex asynchronous serial channels, each with 16-byte transmit and receive FIFOs, programmable baud rates up to 500 kbaud, hardware flow control (RTS/CTS), and in-band Xon/Xoff flow control. It serves as a high-density serial interface controller in industrial terminal servers and data concentrators.

For engineers reviewing the SC28L194A1A,529 datasheet, SC28L194A1A,529 pinout, SC28L194A1A,529 application, or SC28L194A1A,529 equivalent, this device is selected for multi-channel serial bridging where low interrupt overhead, deep FIFO buffering, and dual-voltage compatibility are required - especially in legacy industrial systems requiring drop-in replacement of SC28L198 or SC28L92 derivatives.

Technical Context

The SC28L194A1A,529 implements a synchronous host interface with 33 MHz system clock (SCLK) support, using CEN/W_RN/IACKN/DACKN/IRQN control signals and an 8-bit multiplexed address/data bus. Its timing architecture includes a 2–8 MHz crystal oscillator (X1/X2), a fixed-rate baud rate generator (22 standard rates from 50 to 460.8 kbaud), and two 16-bit programmable BRG timers for non-standard baud generation.

Each of its four UART channels features independent receiver/transmitter clock selection, automatic address recognition in multi-drop mode, three-byte programmable character recognition (for Xon/Xoff or wake-up), and a dedicated watchdog timer (64 receive clock counts). Interrupt arbitration resolves up to 64 sources per channel and reports context via a Current Interrupt Register (CIR) that drives vectored interrupt vectors.

Key Specifications

Pinout & Package

SC28L194A1A,529 is supplied in a 68-pin Plastic Leaded Chip Carrier (PLCC), SOT188-2 package. Pin assignments are defined for industrial temperature range (−40 °C to +85 °C) and include dedicated V_{SS_IC}/V_{CC_I} (input/noise-sensitive circuits) and V_{SS_O}/V_{CC_O} (high-current drivers) power rails.

Key Features

Applications

Equivalent & Alternatives

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

Compared with SC28L194A1A,529, the SC28L198B1A,529 offers double the channel density but demands more board space and power, while the TL16C550CPTR provides register compatibility at the cost of system-level integration - making SC28L194A1A,529 optimal for compact, interrupt-efficient industrial serial hubs.

Availability

SC28L194A1A,529 is available at Aetrix Electronics and suitable for industrial terminal servers, process data concentrators, and ISDN front-end controllers requiring stable component supply across extended product lifecycles.

Supply support for SC28L194A1A,529 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 acquired Philips Semiconductors in 2006 and continues to support legacy communications ICs with long-term availability commitments and industrial qualification.

The SC28L194A1A,529 belongs to NXP's legacy UART product line, designed specifically for high-reliability serial infrastructure in industrial automation, telecom gateways, and embedded control systems where multi-channel integration and deterministic interrupt latency are critical.

FAQ

What voltage supplies does the SC28L194A1A,529 support?

The SC28L194A1A,529 operates from a single 3.3 V ±10 % or 5.0 V ±10 % supply - no level shifters or dual-rail regulators needed. Internal circuitry maintains TTL-compatible I/O thresholds across both voltages, and power domains (V_{SS_IC}/V_{CC_I} and V_{SS_O}/V_{CC_O}) are segregated to minimize noise coupling. This makes SC28L194A1A,529 ideal for mixed-voltage industrial backplanes.

Does the SC28L194A1A,529 support hardware flow control?

Yes, the SC28L194A1A,529 supports full RTS/CTS handshaking per channel via dedicated I/O pins (I/O0–3a–d), and also implements in-band Xon/Xoff flow control using user-programmable characters recognized by on-chip CAM. Both methods operate independently and can be enabled simultaneously - a capability confirmed in the "Flow Control" section of the 2006 datasheet for SC28L194A1A,529.

How many interrupt sources does the SC28L194A1A,529 handle per channel?

The SC28L194A1A,529 supports 16 interrupt sources per UART channel - including FIFO fill/empty levels, parity/framing errors, break detection, change-of-state on I/O pins, watchdog timeout, and Xon/Xoff/address recognition. With four channels, the interrupt arbitration system evaluates up to 64 total contenders, prioritizing based on programmable threshold values stored in global registers.

Can the SC28L194A1A,529 generate non-standard baud rates?

Yes, the SC28L194A1A,529 generates non-standard baud rates using two 16-bit programmable BRG timers, each selectable from eight clock sources. The formula n = (BRG Timer Input Frequency) / (2 × 16 × desired baud rate) – 1 determines reload value, enabling precise rates up to 500 kbaud. This capability is explicitly documented for SC28L194A1A,529 in the "BRG Timers" section of the 2006 datasheet.

What is the maximum system clock (SCLK) frequency supported by the SC28L194A1A,529?

The SC28L194A1A,529 supports a maximum system clock (SCLK) frequency of 33 MHz, with a minimum requirement that SCLK be strictly greater than twice the X1/CCLK frequency. At 33 MHz, it achieves a 125 ns bus cycle time and 15 ns data bus release - verified in the "AC Electrical Characteristics" table of the official SC28L194A1A,529 datasheet.