How to Use a Photocoupler Check

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Step 4. Check each constant.
Consider whether there is sufficient margin for operating temperature, speed, lifetime design, tolerance of resistor, etc.

How to Use a Photocoupler Check

Temperature range ⇒ VF, CTR, allowable current, etc.

Load resistance ⇒ switching speed, influence of dark current, etc.

Allowable current
Allowable current
CTR-Ta
CTR-Ta
Dark current
Dark current
Switching time -RL
Switching time -RL

Confirmation of lifetime of the set

The optical output of the input LED of photocoupler decreases with the passage of time.

It is necessary to confirm that the characteristics are satisfied, for which purpose this deterioration during the lifetime target of the set must be included.

The aging variation of the optical coupler can be calculated from input current (IF) and ambient temperature.

Confirmation of lifetime of the set

Chapter V : Optical Semiconductors

Types of Optical Semiconductors
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Light-Emitting Principal of LEDs
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The wavelength range of LEDs
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What Is a Photocoupler?
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Why Are Photocouplers Necessary?
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Types of Photocouplers
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Types of Photocouplers (Packages)
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Types of Photocouplers (Internal Structure)
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Safety Standards of Photocouplers
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Characteristics of Photocouplers (Current Transfer Ratio: CTR)
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Principal Characteristics of Photocouplers (Trigger LED Current)
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Aging Variation Data of Photocouplers
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How to Use a Photocoupler
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How to Use a Photocoupler “Input Current”
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How to Use a Photocoupler “Output Current”
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How to Use a Photocoupler “Output-Side Resistor”
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