How to Use a Photocoupler
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Design example of signal interface using phototransistor coupler
The figure below shows an example of an interface circuit that converts a 5 V signal into a 10 V signal using a phototransistor coupler.
How should we design the resistor RIN on the LED input side and the resistor RL on the phototransistor output side?
And how should we select CTR of the phototransistor coupler?
We will explain from the next page with the following steps.
Step 1. Design of LED input-current IF and input-side resistor RIN
Step 2. Calculate output current from IF and CTR
Step 3. Design of output-side resistor RL
Step 4. Check each designed constant
Chapter V : Optical Semiconductors
Types of Optical Semiconductors
Light-Emitting Principal of LEDs
The wavelength range of LEDs
What Is a Photocoupler?
Why Are Photocouplers Necessary?
Types of Photocouplers
Types of Photocouplers (Packages)
Types of Photocouplers (Internal Structure)
Safety Standards of Photocouplers
Characteristics of Photocouplers (Current Transfer Ratio: CTR)
Principal Characteristics of Photocouplers (Trigger LED Current)
Aging Variation Data of Photocouplers
How to Use a Photocoupler “Input Current”
How to Use a Photocoupler “Output Current”
How to Use a Photocoupler “Output-Side Resistor”
How to Use a Photocoupler Check
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