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Stand Alone UART - SIO8 IC

8 Bits Serial Input/Output

General Description

The SIO8 IC is a stand alone UART designed to provide 8 bits of input and output data to connect to RS-232, USB, RS-485, Ethernet or directly to your UART. Outputs can be used to drive relays, logic, optocouplers or a transistors. Inputs can be from switches, relay contacts, logic, optocouplers or a transistor switched to ground. The SIO8 has internal pull resistors on most inputs to minimize additional parts. If the MODE pin is open or high, the data on the IA0-7 pins are transmitted only after a byte is received on the SIN- pin. If the MODE pin is low, the SIO8 IC transmits data anytime the inputs change or every of 100 mS, or 1000 mS, depending on the state of the SPD pin. A positive pulse is generated on the RXP pin every time a byte is received on the SIN- pin. The serial format to the SIO8 is standard asynchronous format, using 8 bits, 1 stop and no parity at 9600 BPS. Other formats and encoding are available, contact the factory. A .1 uF bypass capacitor is suggested across the VDD and VSS pins. The part uses the standard 28 pin .3 inch width SOIC and DIP package.


  • Asynchronous serial control for 8 bits of input and 8 bits of output.
  • Can connect with RS-232, RS-485, USB or Ethernet or UART.
  • Inputs can be switches, relay contacts, optocouplers, and logic.
  • On chip input pull up resistors on most inputs.
  • Outputs can be used to drive relays, transistors, optocouplers, and logic.
  • No external parts required.
  • vLow power consumption 5 mA typical. vSupply voltage 2.4 to 5.25 volts.
  • All timing internally generated.
  • TTL and CMOS compatible inputs and outputs.
  • Part is in full production.
  • SOIC and DIP 28 Pin Package.
  • ROHS Compliant.
  • Low EMI.

Example Circuits

Spec sheet: SIO8 Stand Alone UART - Serial Input/Output IC - 8 Bits Input, 8 bits output

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