NXP Semiconductors SC28L194A1A,512

Overview

SC28L194A1A,512 from NXP Semiconductors (formerly Philips) is a quad-channel CMOS UART IC supporting simultaneous 3.3 V and 5 V operation, featuring four independent full-duplex asynchronous serial channels, 16-byte transmit/receive FIFOs per channel, programmable baud rates up to 500 kbaud, and hardware/software flow control (RTS/CTS and XON/XOFF). It serves as a high-density serial interface controller in industrial terminal servers and data concentrators.

For engineers reviewing the SC28L194A1A,512 datasheet, SC28L194A1A,512 pinout, SC28L194A1A,512 application, or SC28L194A1A,512 equivalent, this device delivers deterministic interrupt arbitration, multi-drop address recognition, and synchronous host bus timing - critical for legacy system upgrades requiring reliable multi-channel RS-232/RS-485 bridging with minimal CPU overhead.

Technical Context

The SC28L194A1A,512 integrates a synchronous host interface (SCLK up to 33 MHz), a shared baud rate generator producing 22 standard rates (50–230.4 kbaud), two 16-bit programmable BRG timers for non-standard rates, and four independent UART channel blocks - each with dedicated status/interrupt registers, 16-byte FIFOs, and character recognition logic for XON/XOFF and 9-bit address detection.

Its interrupt arbitration system evaluates 64 sources across all channels, encoding FIFO fill/empty levels, error conditions, and change-of-state events into a 4-bit priority value concatenated with channel and source ID; the Current Interrupt Register (CIR) provides immediate context on IACKN, enabling vectored ISR dispatch without polling.

Key Specifications

Pinout & Package

SC28L194A1A,512 is housed in a 68-pin Plastic Leaded Chip Carrier (PLCC), SOT188-2 package, with dedicated V_{SS_IC}/V_{CC_I} (input/noise-sensitive circuits) and V_{SS_O}/V_{CC_O} (output/high-current drivers) supply pins to minimize noise coupling between analog and digital sections.

Key Features

Applications

Equivalent & Alternatives

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

Compared with XR16L788IQ-F and SC16C752BIBS,151, the SC28L194A1A,512 uniquely balances 4-channel density, PLCC mountability, dual-voltage support, and legacy register compatibility - making it the optimal choice for industrial retrofits and fixed-port terminal servers where footprint and firmware continuity are mandatory.

Availability

SC28L194A1A,512 is available at Aetrix Electronics and suitable for industrial terminal servers, building automation systems, and legacy equipment integration requiring stable component supply across extended product lifecycles.

Supply support for SC28L194A1A,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 communications IC development.

The SC28L194A1A,512 belongs to NXP's legacy industrial UART family, engineered specifically for high-reliability serial infrastructure in factory automation, process control, and data concentration - emphasizing long-term availability, noise-immune design, and register-level compatibility with prior-generation controllers.

FAQ

What is the maximum baud rate supported by SC28L194A1A,512?

The SC28L194A1A,512 supports up to 500 kbaud using its programmable BRG timers with external clock inputs. Standard fixed rates reach 230.4 kbaud (or 460.8 kbaud when doubling with 7.3728 MHz crystal), and non-standard rates are achievable via timer reload values calculated per the formula n = (BRG Timer Input Frequency) / (2 × 16 × desired baud rate) − 1. The SC28L194A1A,512 maintains timing integrity at these rates due to its 16× oversampling architecture and false start-bit rejection.

Does SC28L194A1A,512 support both 3.3 V and 5 V operation simultaneously?

Yes - the SC28L194A1A,512 operates from a single supply rail at either 3.3 V ±10 % or 5.0 V ±10 %, with full TTL/CMOS interface compatibility at both voltages. It does not require dual supplies; V_{CC_I}, V_{CC_O}, and V_{CC_C} pins are internally regulated or bonded to the same supply, enabling seamless integration into mixed-voltage systems without level translation circuitry.

How does the interrupt arbitration system in SC28L194A1A,512 reduce CPU overhead?

The SC28L194A1A,512 uses a priority-encoded arbitration system that evaluates 64 interrupt sources (including FIFO levels, errors, and change-of-state events) and latches the highest-priority source into the Current Interrupt Register (CIR) on IACKN. A single read of CIR returns channel number, interrupt type, and FIFO fill level - eliminating polling loops and enabling direct vectoring to service routines. This reduces average interrupt latency to under 2 µs in typical industrial use cases.

Can SC28L194A1A,512 be used in multi-drop RS-485 networks?

Yes - the SC28L194A1A,512 supports 9-bit multi-drop mode with automatic address character recognition. Each UART channel can be configured to detect a programmable 9th bit address, allowing selective wake-up and command targeting in daisy-chained RS-485 configurations. This capability is implemented in hardware, requiring no host CPU intervention beyond initial setup of the address registers.

What is the purpose of separate V_{SS_IC}/V_{CC_I} and V_{SS_O}/V_{CC_O} pins on SC28L194A1A,512?

The SC28L194A1A,512 separates analog/noise-sensitive circuitry (V_{SS_IC}/V_{CC_I}) from high-current output drivers (V_{SS_O}/V_{CC_O}) to prevent switching noise from corrupting internal timing and receiver sensitivity. Decoupling capacitors must be placed near each pair; mixing these supplies risks increased bit-error rates, especially at high baud rates or in electrically noisy industrial environments.