XL9535 relay board power suply

[mahnunchik]

Could you please tell me if it is necessary to supply power in addition to the I2C interface power? The power indicator lights up after only the I2C interface is connected.

[mcauser]

Option 1: Power the board and all relays with the input JST (next to USB), as pictured. VIN supports 3.3 or 5V. Not 12V!
Keep J1 jumper connected to bridge the input JST VIN->all other 5V pins and relays.
Disconnect the terminal block, unless you want 3.3/5V out.

Option 2: Dual power rails. Input JST powers the XL9535 IO expander only. None of the relays.
Disconnect J1 jumper to remove input JST's VIN from 5V rail.
Connect a 5V power source to either of the 2 JSTs at the top, the DC jack or the USB-C connector. They are all connected.
All of the relays are powered by this secondary source, with a common ground.

The I2C SDA/SCL/GND pins on all 3 JSTs are connected.

[mahnunchik]

@mcauser Thank you a lot for the clarification!