A small PCB to control power to a USB device. I've designed this in order to be able to cut power to a HDMI display when it's not in use, for example, via a Raspberry Pi.
- MicroUSB input
- USB Type A output
- Maximum permissible USB current draw: 1A
- JST XH to control the power. Control voltage 3.3V or 5V.
- Active power consumption 35mA (only when switched on)
- USB data lines are passed through
- One mounting hole is offset to the right by 0.5mm, the DIN mounting adapter is adjusted for that.
| Designator | Part |
|---|---|
| D1 | 1N4148 DO35-10 |
| K1 | V23079-A1011-B301 |
| Q1 | 2N7002 SOT23 |
| R1 | 100k 0805 |
| X1 | JST XH 2 pin |
| X2 | AMP 787616-1 |
| X3 | 10104110-0001LF |
Why a relay?
I didn't have any P-channel mosfets in stock, but plenty of those small relays, so that's why I based my design around them. I rather use components I have in stock than to order new ones.
N-channel mosfets shouldn't be used to control USB power due to possible leakage over the data lines.
Why not use the RPI4 USB power control functionality?
On a Raspberry Pi 4, this cuts power to all USB ports. In my case, I only want the display to be turned off. All other ports should remain on.