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Stand Alone UART - SIOA7 IC

7 Bits Serial Input/Output Expandable and Addressable

General Description

The SIOA7 IC is a stand alone UART designed to provide 7 bits of input and output data. (Expandable to 112 bits.) The SIOA7 may 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 SIOA7 has internal pull resistors on most inputs to minimize additional parts. After receiving an address byte matching the ADR0-3 pins is received on the SIN- pin, the next bye received on the SIN- pin is placed on the OA0-6 pins and the data on the IA0-6 pins are transmitted SOUT- pin. A positive pulse is generated on the RXP pin every time a byte is placed on the OA0-6 pins. More than one SIOA7 chip may be connected together to achieve up to 112 bits of input and output. The serial format to the SIOA7 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 7 bits of input and 7 bits of output, expandable to 112 bits.
  • 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.
  • Low power consumption 5 mA typical.
  • Supply 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: SIOA7 Stand Alone UART - Serial Input/Output IC - 7 Bits Input, 7 bits output Expandable and addressable

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