Principal Characteristics of Photocouplers (Trigger LED Current)

Trigger LED current
Trigger LED current is specified for products that perform binary operation of output ON/OFF such as IC coupler of logic output, photorelay, and triac output coupler.

 “Trigger LED current” means “LED current that triggers change in the status”.

 I_FT, I_FLH, I_FHL, etc., are used as symbols.

The trigger LED current indicated in the datasheet is the value specified by the product. For stable operation, the designer must design so that at least the trigger LED current (maximum) flows.

The input LED current I_F is gradually increased from 0 mA,
If the output shifts to the on state at 1 mA, I_FT = 1 mA.
In the following data sheet, the I_F required to shift the output to the ON state
It means that the maximum value is 3 mA.

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