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I am planning to switch the 5V line to a USB load.

I have being going around different suppliers looking for an optocoupler that can handle 3A at 5V. I have seen a few, but upon looking at the datasheet (e.g., FOD3182), they mentioned that the operating voltage should be at 15 to 30V.

If there aren't any such optocouplers, how can I solve my problem?

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  • \$\begingroup\$ Please see the Help Center for rules about shopping questions. Your question will be closed if it remains in its current form. You need to change it to a design question. You also omitted to link to the device datasheet. \$\endgroup\$
    – Transistor
    Jun 11, 2016 at 8:21

3 Answers 3

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If there aren't any such optocouplers, just build your own:

optocoupler switches MOSFET

The actual optocoupler needs to pass very little current because it controls only the gate of the MOSFET.

Choose a logic-level MOSFET that switches on completely at VGS=−5V, and has a low enough RDS(on) for your application.

In this circuit, the optocoupler activates the switch. To invert the logic, exchange IC1 and R1.

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An optocoupler than can handle that load exists, but it has a different name: "solid-state-relay"

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You can use 4n35 with N mos as in this diagram: http://www.alcs.ch/webdata/arduino/dimmer/dimmer_v1.png

What will be the load ? Because you may need extra diode for motor load for exemple

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