Characteristics of Photocouplers (Current Transfer Ratio: CTR)
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Current transfer ratio of transistor coupler: It is expressed by the amplification ratio of the output current with respect to the input current like the transistor hFE.
Current Transfer Ratio=CTR
=IC/IF =Output (collector) current/input current ×100 (%)
E.g.）
When IF = 5 mA is input, IC = 10 mA is obtained.
CTR = IC /IF = 10 mA/5 mA×100 (%) = 200%
Reference: hFE of bipolar transistor
hFE (DC current gain)
= Collector current (IC)/base current (IB)
Chapter V : Optical Semiconductors (Isolators/Solid State Relays)
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
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 “Output-Side Resistor”
How to Use a Photocoupler Check
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