Controlling the shutdown pin of an IR Transceiver

If the MCU is also running on 3.3V, you could connect an output directly to the shutdown pin, preferably via a series resistor?

Or if they are powered separately, you must use a series resistor (eg. 100k) to limit the current if the device is accidentally enabled while not powered.

The maximum load current is only 1uA, so such a resistor has near enough no effect on the voltage in switching applications such as this, but can prevent accidental damage to an input.

If the MCU is working on 5V, you could use a resistive divider at the output, such as 1k8 and 3k3 (or some other combination giving a similar ratio), then the series limiting resistor from the divider output to the shutdown pin.

The MCU is also working at 3.3V

newbe_always said:

The MCU is also working at 3.3V

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OK, you don't need any kind of buffering ore interfacing then, as long as they are on the same supply.

If the IR part is separate (eg. on a cable or plug & socket), I'd still add a series resistor in line with each data connection.