Diodes Incorporated
Back to UART - Universal Asynchronous Receiver / Transmitter


16C550 Octal UART Bridge Controller

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The PI7C9X798 (798), is a 1.62V to 3.6V octal Universal Asynchronous Receiver and Transmitter (UART) with 5V tolerant serial (modem) inputs. The highly integrated device is designed for high bandwidth requirement in communication systems. The global interrupt source register provides a complete interrupt status indication for all 8 channels to speed up interrupt parsing. Each UART has its own 16C550 compatible set of configuration registers, TX and RX FIFOs of 64 bytes, fully programmable transmit and receive FIFO trigger levels, TX and RX FIFO level counters, automatic RTS/CTS or DTR/DSR hardware flow control with programmable hysteresis, automatic software (Xon/Xoff) flow control, RS-485 half-duplex direction control, and auto address detection, Intel or Motorola bus interface and sleep mode with a wake-up indicator.


  • 1.62V to 3.6V with 5V Tolerant Serial Inputs
  • Single Interrupt output for all 8 UARTs
  • A Global Interrupt Source Register for all 8 UARTs
  • 5G “Flat” UART Registers for easier programming
  • Simultaneous Initialization of all UART channels
  • A General Purpose Command-driven 16-bit Timer/counter
  • Sleep Mode with Wake-up Indication
  • Highly Integrated Device for Space Saving
  • Each UART is independently controlled with:

      - 16C550 Compatible 5G Register Set
      - 64-byte Transmit and Receive FIFOs
      - Transmit and Receive FIFO Level Counters
      - Programmable TX and RX FIFO Trigger Level
      - Automatic RTS/CTS or DTR/DSR Flow Control
      - Automatic Xon/Xoff Software Flow Control
      - RS485 HDX Control Output
      - RS485 auto address detection
      - Infrared (IrDA 1.0/1.1) Data Encoder/Decoder
      - Programmable Data Rate with Prescaler

  • Up to 8 Mbps Serial Data Rate with 64MHz external clock input
  • Crystal oscillator(up to 24MHz) or external clock(up to 80MHz) input
  • Built in Power-On-Reset circuit


  • Remote Access Servers
  • Ethernet Network to Serial Ports
  • Network Management
  • Factory Automation and Process Control
  • Point-of-Sale Systems
  • Multi-port RS-232/RS-422/RS-485 Cards

Product Specifications

Product Parameters

Ports 8 UART
Pins 100
Data Rate (kbps) 20Mbps
Bytes 64
Tx/Rx FIFO Ctrs Yes
Tx/Rx FIFO INT Trig Yes
Auto RTS/CTS Yes
Interface 8-Bits
Ambient or Junction Temperature (°C) -40 to 85

Technical Documents

Recommended Soldering Techniques


Additional Technical Documents are available upon request:
Application information, Evaluation board, and Other technical documents

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