what to use for micro switch (relay, transistor, optocoupler)

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Hey,
Im absolutely new to eda, i want to design a very compact battery powered esp32 based pcb, one function of it is to power a micro water pump.
The Pump uses 5V with 160mA, I need the ability to (just) switch it on and off using the esp32.
To my knowledge the options are transistors, optocouplers and relays. I have not found a relay small enough to fit my likings, while using transistors and optocouplers in parts seems overkill (but also not unusual for what i have seen). I would really be thankful for some tips and maybe even suggestions about specific models.
 

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Hi,

I personally ´d use a digital transistor if I want it small. (SOT-23 3 pin)
Or a low side power switch if I want reliable operation.

also possible: N-Ch MOSFET logic level, NPN with base resistor. Use some protection diode at the motor.

There are many other ways.

Klaus
 

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Logic-level low side NMOSFET would be fine if your board has 5V output swing. At lower supplies a cheap MOSFET driver w/ "TTL compatible" inputs could work down to maybe 1.8V in (2.5V slam dunk) with 5V supply and skip the FET, as output strength is >1A and the output "catch diodes" may help prevent flyback damage. People used to use bare UC3825 PWM outputs for low power DC-DC as those were good for about 800mA pk.

But it's hard to beat a NPN and a base limiting resistor, for robust and low min working voltage and simplicity.
 
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