PhotoMOS® Relays

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What makes PhotoMOS® technology so successful?Modern semiconductor technology enables fast, quiet, bounce-free switching, even in miniature sizes. PhotoMOS® relays nevertheless enjoy an almost unlimited lifetime if used according to the specifications. Moreover, they are extremely reliable, unaffected by vibrations, and their ON-resistance remains stable throughout their entire lifetime.

PhotoMOS® Technology

Light emitted from an LED on the input side passes through an isolator permeable to light and is detected by a solar cell. Via a trigger circuit, the solar cell's output voltage controls the gates of two source-coupled MOSFETs at the output. This arrangement allows PhotoMOS® relays to switch both AC and DC loads. The integration of MOSFET technology in PhotoMOS® relays differentiate them signifycantly from semiconductor relays with triacs or transistors at the output.


  • Linear output characteristics
  • No threshold voltage
  • Low operating current (sensitive type ≤ 0.31mA)
  • Low output capacitance (RF type ≤ 1pF)
  • Absolute minimum leakage current (pA)
  • Extremely long lifetime
  • Stable ON-resistance over the entire lifetime
  • Extremely compact design (VSSOP, SON, SSOP, SOP)
  • No contact bounce
  • Highly resistant to shock and Vibration
  • Flexible mounting orientation


  • Measuring devices and technology
  • IC and PC board testers
  • Multiplexers
  • Medical technology
  • Industrial control systems
  • Battery management
  • Signal/alarm contacts
  • Outputs for programmable controllers
  • Pulse and counter outputs
  • Isolation monitoring