Browse Prior Art Database

Opto Isolation for Digital Input Circuits

IP.com Disclosure Number: IPCOM000039023D
Original Publication Date: 1987-Apr-01
Included in the Prior Art Database: 2005-Feb-01
Document File: 2 page(s) / 26K

Publishing Venue

IBM

Related People

Bancroft, CE: AUTHOR [+3]

Abstract

A technique is described whereby a circuit may be attached to an existing digital input circuit board, so as to allow computers to receive signals which may contain high voltage transients. The concept is unique in that low voltage signal level computers may now receive high voltage signals directly, thereby eliminating the need to filter out or to convert the high voltage signals prior to entry into the computer. The circuit is designed to adapt to commercially available digital input/digital output (DI/DO) circuit boards, utilizing either separate isolation and driver modules or as a combined opto isolation/driver module. The circuit consists of opto isolation integrated circuit (IC) 10, as shown in the figure, resistor 11 and buffer/driver IC 12.

This text was extracted from a PDF file.
At least one non-text object (such as an image or picture) has been suppressed.
This is the abbreviated version, containing approximately 85% of the total text.

Page 1 of 2

Opto Isolation for Digital Input Circuits

A technique is described whereby a circuit may be attached to an existing digital input circuit board, so as to allow computers to receive signals which may contain high voltage transients. The concept is unique in that low voltage signal level computers may now receive high voltage signals directly, thereby eliminating the need to filter out or to convert the high voltage signals prior to entry into the computer. The circuit is designed to adapt to commercially available digital input/digital output (DI/DO) circuit boards, utilizing either separate isolation and driver modules or as a combined opto isolation/driver module. The circuit consists of opto isolation integrated circuit (IC) 10, as shown in the figure, resistor 11 and buffer/driver IC 12. When the circuit is adapted to a DI/DO board, external signals enter the input stage of the opto isolation IC 10 so as to protect the computer circuits from noise or extraneous high voltage transients which may be present. The opto isolation IC 10 consists of a light-emitting diode (LED) 13 and transistors 14 and 15. The maximum input signal voltage is limited by the continuous forward circuit specification of LED 13 and the power dissipation capability of resistor 11. The output of opto isolation IC 10 is fed into buffer/driver IC 12, which converts the signal to the proper transistor voltage levels required for processing by the DI circuitry. When the opto isolation circuit...