How to choose transistor for turning 16x2 screen

Good day!

I'm building a project with standalone ATMega MCU with Arduino bootloader. Most of the time chip is in a sleep mode. When the chip is waked up with external interrupt I need to turn 16x2 LCD screen (LCD controller and backlight) and a couple of sensors.

My plan was to put some transistor and control it using spare digital pin to turn load (LCD, sensors) on and off.

What transistor to choose? Which one will be efficient in terms of power saving (most of the time it will be closed, when MCU is in sleep).

You wouldn’t need a transistor for a 16*2 LCD screen. The most power hungry bit is the backlight which needn’t use more than can safely be supplied through a plain digital pin (with the right resistor). Buy the black on green ones and they don’t need a backlight at all. Without the backlight the display and controller will use a milliamp or two total. The serial ones may use more. ‘Sensors’ could mean anything, most of my sensors use microamps so they wouldn’t need a transistor either.

My favourite transistors for using are the BCxxx (e.g. BC108, BC109, etc). I don't know why I don't use something more suited to whatever project I do, but, they work!

You wouldn't need a transistor for a 16*2 LCD screen. The most power hungry bit is the backlight which needn't use more than can safely be supplied through a plain digital pin (with the right resistor). Buy the black on green ones and they don't need a backlight at all. Without the backlight the display and controller will use a milliamp or two total. The serial ones may use more. 'Sensors' could mean anything, most of my sensors use microamps so they wouldn't need a transistor either.

My sensors are DS18B20, it seems I will use them in parasitic power mode, so they will get power from their own pins. So I can safely power 16x2 LCD (controller and backlight) from spare digital pin?

It seems I really can -- it seems an average 16x2 display (I can't get a datasheet for my particular black on green screen from China, so I checked some common models I know) is about 1.5-3mA.

My permanently ruuning projests use 16x2 LCD Panels and DS18S20s, No transistors anywhere. You might have to allow for re-initialising the LCD in the code each time it wakes up. Mine are permanently running and powered.

You might have to allow for re-initialising the LCD in the code each time it wakes up.

Yes, that's the next task )

Thanks for the response!