Analog Optoisolators and Optocouplers

Excelitas, a leading manufacturer of analog optical isolators (AOI) for over twenty years, makes a broad range of standard parts under its trademark VACTROL®.

The analog optical isolator (AOI) uses an optical link between input and output. The input element is an LED and the output element is a photoconductive cell or simply photocell. Together, the coupled pair acts as an electrically variable potentiometer. Since the output element of the AOI is a resistor, the voltage applied to this output resistor may be DC and/or AC and the magnitude may be as low as zero or as high as the maximum voltage rating. Because the input will control the magnitude of a complex waveform in a proportional manner, this type of isolator is an analog control element. AOIs may be used in the ON-OFF mode but the fastest response time is in the millisecond range. A level sensitive Schmitt trigger is required between the AOI and logic gates when used in digital circuits.

Features:

• High input-to-output voltage isolation
• True resistance element output
• Single- or Dual-element outputs available
• Suitable for AC or DC use
• Wide range of input-to-output characteristics
• Low drive current
• Low "on" resistance, high "off" resistance
• Complete solid-state construction
• Cost effective