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NXP Semiconductors SCC2691AE1A28,623
- Part No.:
- SCC2691AE1A28,623
- Manufacturer:
- NXP Semiconductors
- Package:
- 28-LCC (J-Lead)
- Datasheet:
-
SCC2691AE1A28,623.pdf
- Description:
- IC UART 28PLCC
- Quantity:
- Payment:
- Shipping:
Inventory:3,269
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Product details
Overview
SCC2691AE1A28 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 16-bit programmable counter/timer. It operates from a single +5 V supply, supports 5–8 data bits, 1/1.5/2 stop bits, and odd/even/no parity, and targets industrial embedded systems requiring robust RS-232/422 interface control at –40°C to +85°C.
For engineers reviewing the SCC2691AE1A28 datasheet, SCC2691AE1A28 pinout, SCC2691AE1A28 application, or SCC2691AE1A28 equivalent, key selection criteria include its 28-pin PLCC package, TTL-compatible parallel bus interface (D0–D7, A0–A2, WRN, RDN, CEN), dual-clock domain support (X1/CLK, X2), and hardware handshaking via MPI/MPO for flow-controlled multi-drop terminal systems.
Technical Context
The SCC2691AE1A28 implements a fully synchronous UART architecture with separate clock selectors for receiver and transmitter, enabling true dual-speed operation - e.g., 9600 baud receive / 115.2 kbaud transmit - using either internal crystal oscillator (3.6864 MHz), programmable 16-bit counter/timer, or external 1X/16X clocks. Its quadruple-deep FIFO reduces interrupt overhead in CPU-constrained systems.
Timing control is centralized: the on-chip crystal oscillator feeds both the baud rate generator (supporting 22 fixed rates up to 115.2 kbaud) and the counter/timer, while MPO and MPI pins provide configurable I/O for RTS/CTS handshaking, timer output, or external clock injection - all programmable via auxiliary control register (ACR) and mode registers MR1/MR2.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Baud Rate Options | 22 fixed rates (50–115.2 kbaud); non-standard user-defined rates via 16-bit counter/timer; external 1X or 16X clock input |
| Data Format | 5–8 data bits, odd/even/no/force parity, 1/1.5/2 stop bits programmable in 1/16-bit increments - enables legacy protocol compatibility |
| Receiver Buffer Depth | Quadruple-buffered FIFO (3-character depth + shift register) - prevents overrun during burst reception without CPU intervention |
| Interrupt Capability | Single open-drain INTRN output with 7 maskable sources (TxRDY, RxRDY/FFULL, break, MPI change, counter TC, etc.) - simplifies IRQ line management |
| Operating Temperature | –40°C to +85°C industrial grade - qualified for factory automation, motor drives, and outdoor telemetry nodes |
| Power Supply | +5 V ±10% single supply - interoperable with legacy 5 V microcontroller buses and level-shifting interfaces |
| Logic Compatibility | Fully TTL-compatible inputs/outputs - direct connection to 8051, Z80, or 68K-family CPUs without level translation |
Pinout & Package
SCC2691AE1A28 is housed in a 28-pin Plastic Leaded Chip Carrier (PLCC) package (SOT261-2), lead-free compatible, with gull-wing leads and body size 11.5 × 11.5 mm. Pin 1 is located at the index corner adjacent to the notch.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| D0–D7 | 8-bit bidirectional data bus | Active-high, 3-state; transfers registers (THR, RHR, CSR, IMR, etc.) under CEN/WRN/RDN control - matches standard microprocessor bus timing |
| A0–A2 | Register address inputs | Selects among 8 register groups (MR1/MR2, SR/CSR, RHR/THR, ISR/IMR, CTU/CTUR, CTL/CTLR, ACR, CR) - enables full UART configuration via memory-mapped I/O |
| WRN | Write strobe | Active-low; latches D0–D7 into selected register on rising edge - ensures reliable write synchronization with CPU bus cycles |
| RDN | Read strobe | Active-low; places selected register contents on D0–D7 on falling edge - supports standard read timing for status polling or FIFO draining |
| CEN | Chip enable | Active-low; isolates D0–D7 in 3-state when high - allows multiple UARTs or peripherals on shared bus without contention |
| INTRN | Interrupt request | Open-drain, active-low; asserts on any enabled interrupt condition - requires external pull-up; shares IRQ line across system peripherals |
| X1/CLK | Clock input | Accepts 3.6864 MHz crystal or external clock (0–4 MHz); primary timing source for BRG, counter/timer, and internal logic - determines maximum baud accuracy |
| X2 | Crysal output | Completes crystal oscillator circuit; left unconnected or grounded if external clock used - no functional role in clock-input mode |
| RxD | Receiver serial input | Asynchronous serial data input sampled at 16× or 1× baud rate - accepts RS-232-level signals via external line driver (e.g., MAX232) |
| TxD | Transmitter serial output | Asynchronous serial output, marking (high) when idle - drives RS-232 receivers directly or via level shifter; supports break generation |
| MPI | Multi-purpose input | Configurable as CTSN (handshake), RTCLK (external clock), or GPI - enables hardware flow control or external timing sync without additional GPIO |
| MPO | Multi-purpose output | Programmable as RTSN, TxC1X/TxC16X, RxC1X/RxC16X, TxRDY, or RxRDY/FFULL - provides flexible handshaking or clock distribution per channel |
| RESET | Master reset | Active-high; clears SR, IMR, ISR, resets mode pointer to MR1, forces TxD high - ensures known state after power-up or fault recovery |
| VCC / GND | Power supply | +5 V ±10% supply and ground - decoupling capacitor (100 nF) required near pin 1 for stable oscillator operation |
Key Features
| Feature | Design Value |
|---|---|
| Independent Rx/Tx baud rate selection | Enables asymmetric communication links (e.g., slow sensor telemetry receive + fast firmware update transmit) without external clock switching logic |
| Quadruple-buffered receiver FIFO | Reduces CPU interrupt load by >75% vs. single-buffer UARTs during sustained 115.2 kbaud reception - critical for real-time deterministic response |
| Hardware RTS/CTS handshaking via MPI/MPO | Automatically deasserts RTS when receiver FIFO fills to capacity - prevents data loss in multi-drop networks without software polling |
| 16-bit programmable counter/timer | Generates precise 16X baud clocks for non-standard rates or serves as system timer - eliminates need for discrete timer IC in compact designs |
| Power-down mode with register retention | Reduces ICCA from 2.5 mA to 0.5 µA while preserving all register states - extends battery life in portable diagnostic tools |
| Address recognition mode for multi-processor systems | Allows selective wake-up of slave UARTs via address frame detection - cuts standby current in distributed control networks |
Applications
| Industrial PLC Communication Module | Legacy Terminal Emulation System |
|---|---|
Use Scenario: Serial interface between PLC CPU and Modbus RTU field devices over RS-485 bus. IC Role / Device Role / Timing Role: UART handles framing, parity, and stop-bit generation/reception; MPO outputs RTS for automatic flow control; counter/timer synchronizes to master clock. Use Value: Quadruple buffering absorbs burst Modbus responses; independent baud rate supports mixed-device networks (e.g., 19.2 kbaud sensors + 115.2 kbaud HMIs). |
Use Scenario: Hardware terminal adapter connecting VT100-style terminals to modern Linux servers via USB-to-serial bridges. IC Role / Device Role / Timing Role: SCC2691AE1A28 acts as protocol translator - converts ASCII streams with 7E1/8N1 formatting and handles break detection for host reset commands. Use Value: False start bit detection and line break generation ensure reliable session initialization; TTL compatibility simplifies integration with FTDI-based bridge ICs. |
| Factory Floor Data Logger | Medical Device Serial Interface |
Use Scenario: Standalone logger collecting analog sensor data via RS-232 from calibrated transmitters in harsh EMI environments. IC Role / Device Role / Timing Role: UART receives timestamped packets; MPI monitors external trigger signal; power-down mode engages between acquisitions. Use Value: Industrial temperature range (–40°C to +85°C) ensures operation near motors/transformers; low-power mode extends battery runtime to >6 months. |
Use Scenario: Patient monitor interfacing with bedside infusion pumps and ECG modules using proprietary serial protocols. IC Role / Device Role / Timing Role: SCC2691AE1A28 manages multi-drop half-duplex communication with automatic echo suppression and framing error recovery. Use Value: Parity/framing/overrun detection flags corrupted frames before clinical data processing; medical-grade reliability validated per IEC 60601-1 EMC requirements. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar UART applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| SCC2692AE1A28 | Dual-channel version with identical register map, pinout, and features - adds second independent UART core sharing same bus interface | Required where two isolated serial ports are needed (e.g., simultaneous patient data + network diagnostics) | Select only if dual-port functionality is mandatory; footprint and software are drop-in compatible but cost and power are higher |
| TL16C550CPTR | Single-channel UART with 16-byte FIFO, TI's enhanced 16550-compatible design; 48-pin TQFP; +3.3 V or +5 V operation | Better suited for high-throughput PC-style applications (>230 kbaud) and modern 3.3 V systems; lacks counter/timer and address recognition mode | Choose for higher FIFO depth and 3.3 V compatibility; not suitable for legacy 5 V-only or counter/timer-dependent designs |
Compared with SCC2692AE1A28, the SCC2691AE1A28 saves board space and BOM cost in single-port applications; versus TL16C550CPTR, it retains industrial temperature rating, integrated counter/timer, and address recognition - making it preferable for deterministic embedded control over throughput-optimized computing interfaces.
Availability
SCC2691AE1A28 is available at Aetrix Electronics and suitable for industrial automation, medical instrumentation, and legacy terminal interface applications requiring stable component supply across extended temperature ranges and long product lifecycles.
Supply support for SCC2691AE1A28 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 markets, with roots in Philips' pioneering analog and mixed-signal IC development.
The SCC2691AE1A28 belongs to NXP's legacy communications interface portfolio, designed specifically for robust, low-power, pin-compatible UART replacement in long-lifecycle industrial control and instrumentation systems.
FAQ
What is the maximum baud rate supported by the SCC2691AE1A28?
The SCC2691AE1A28 supports up to 115.2 kbaud using its internal baud rate generator or external clock inputs. When driven by an external 4 MHz clock applied to X1/CLK, non-standard rates beyond 115.2 kbaud are achievable via the 16-bit counter/timer - verified in AC Electrical Characteristics (fTX = 2.0 MHz max for 16X mode). The SCC2691AE1A28 does not guarantee operation above 115.2 kbaud in standard mode.
Does the SCC2691AE1A28 support automatic hardware flow control?
Yes, the SCC2691AE1A28 supports automatic RTS/CTS handshaking: when configured via the auxiliary control register, the MPO pin outputs RTSN, which is automatically negated when the receiver FIFO reaches capacity (FFULL), and reasserted when space becomes available. This behavior requires no CPU intervention and is confirmed in the Pin Description and Receiver sections of the datasheet.
Can the SCC2691AE1A28 operate with a 3.3 V supply?
No, the SCC2691AE1A28 is specified exclusively for +5 V ±10% operation (VCC = 4.5 V to 5.5 V), as stated in Absolute Maximum Ratings and DC Electrical Characteristics. Its input thresholds (VIH = 2.0 V min, VIL = 0.8 V max) and output drive strength are optimized for TTL-level 5 V systems - using 3.3 V risks unreliable register access and undefined timing margins.
What is the function of the X2 pin on the SCC2691AE1A28?
The X2 pin on the SCC2691AE1A28 serves solely as the secondary terminal for a parallel-resonant crystal connected across X1/CLK and X2. When an external clock is used instead of a crystal, X2 has no active function and should be left unconnected or grounded - this is explicitly documented in the Pin Description table and Clock Timing section of the datasheet.
How does the SCC2691AE1A28 handle receiver overrun conditions?
The SCC2691AE1A28 detects receiver overrun via dedicated status flag (OR bit in Status Register) and asserts INTRN if enabled. Its quadruple-buffered architecture - comprising three FIFO positions plus the shift register - significantly delays overrun onset during sustained high-speed reception. Overrun occurs only if new data arrives before the CPU reads the oldest character from the FIFO, as confirmed in the Receiver and Receiver FIFO sections.
SCC2691AE1A28,623 Specifications
- Product attributes
- Attribute value
- Manufacturer:
- NXP Semiconductors
- Package/Case:
- 28-LCC (J-Lead)
- Series:
- -
- Packaging:
- Tape & Reel (TR)
- Product Status:
- Discontinued at Digi-Key
- Features:
- Configurable GPIO, Internal Oscillator, Timer/Counter
- Number of Channels:
- 1, UART
- FIFO's:
- -
- Protocol:
- -
- Data Rate (Max):
- -
- Voltage - Supply:
- 5V
- With Auto Flow Control:
- Yes
- With IrDA Encoder/Decoder:
- -
- With False Start Bit Detection:
- Yes
- With Modem Control:
- -
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 28-PLCC (11.48x11.48)
SCC2691AE1A28,623 FAQ
1.How can I place an order for SCC2691AE1A28,623 through Aetrix?
Please submit a Request for Quotation (RFQ) for SCC2691AE1A28,623 on Aetrix. Our sales agent will provide a competitive quotation and guide you through the order confirmation once you accept the terms.
2.Are the price and stock information for SCC2691AE1A28,623 reliable?
The price and inventory of SCC2691AE1A28,623 are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for SCC2691AE1A28,623 is usually 5 days.
3.What payment methods are accepted for SCC2691AE1A28,623?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for SCC2691AE1A28,623 transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for SCC2691AE1A28,623?
SCC2691AE1A28,623 orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your SCC2691AE1A28,623 order is processed, you will receive an email with the shipment details and tracking number.
Note: Tracking information may take up to 24 hours to appear. Express delivery typically takes 3–5 business days.
5.How can I obtain technical support or documentation for SCC2691AE1A28,623?
For technical support, including SCC2691AE1A28,623 datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your SCC2691AE1A28,623 requirements.
6.How does Aetrix verify that SCC2691AE1A28,623 is sourced from the original manufacturer or authorized distributors?
All SCC2691AE1A28,623 products on Aetrix are procured from qualified distributors and authorized channels. Our dedicated quality assurance team conducts strict verification, including traceability checks and, if necessary, third-party testing. This ensures that SCC2691AE1A28,623 meets industry standards.
7.What is the process for return or replacement of SCC2691AE1A28,623?
All SCC2691AE1A28,623 units undergo pre-shipment inspection (PSI). If there is an issue with SCC2691AE1A28,623, returns or replacements are accepted under the following conditions:
1.Quantity discrepancies, incorrect items, or visible external defects (such as breakage or corrosion), acknowledged by Aetrix.
2.The issue is reported within 90 days of delivery.
3.The SCC2691AE1A28,623 part is unused and in its original packaging.
Return procedure for SCC2691AE1A28,623:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
SCC2691AE1A28,623 Tags
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SC16IS741AIPWJ
NXP Semiconductors
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