Power supply for an external LCD module with the ability to turn it off

Banana Pi Router design BPI-R4/BPI-R4 Pro(MT7988)
1

Hello, all! I need to power an external LCD display (5v DC, max current consumption is 300 mA). I want power to be supplied to the LCD when the BPI-R4 is powered on, and for it to be turned off when a “poweroff” command is issued from the Linux shell. Where can I get such controlled power? Possibly from the GPIO 26-pin header (pin 2,4)?

And one more question: I could not find any information on the maximum current the 5V GPIO (CON2, GPIO 26-pin header) can provide on pins 2 and 4?

Thank you in advance.

2

Usually you can use any buck converter with an enable pin.

But be careful, you may want to check the voltage on that enable pin, as it might have a pull-up resistor to high 5V. This is too high for your GPIO pin, if using a GPIO output pin for control.

So then use an opto-coupler or an i2c voltage converter module.