How to Use a Photocoupler “Output-Side Resistor”
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Step 3. Design output-side resistor RL
Determine RL from the IC-VCE characteristics of the output transistor. In order to use for signal transmission, it is necessary to fully satisfy the "L" level of the device connected to the load side.
Here, we set VCE = 0.3 V as the target value.
When IF = 10 mA, VCE = 0.9 V at RL = 1 kΩ, which is insufficient. At RL = 2 kΩ, VCE = about 0.2 V, which satisfies the target value. Therefore, choose RL = 2 kΩ. In actual design, the impedance on the load side must also be considered.
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
How to Use a Photocoupler “Input Current”
How to Use a Photocoupler “Output Current”
How to Use a Photocoupler Check
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