This module adds a 3.3V LDO and level shifter to the typical breakout for the PCF8575 GPIO Expander.
The module connects via the I2C bus to your Microcontroller and offers I2C address selection by closing solder jumpers on the bottom side (base address is 0x20).
You can either use it on 3.3V or 5V thanks to its on-board LDO and level shifter.
The VDD pin is the power supply for 5V, the VCC pin is the 3.3V output voltage of the LDO. If you use it as 5V device, you supply 5V on VDD. If you use it as 3.3V device, you supply 3.3V to the VCC pin and close the solder jumper VCC-VDD on the bottom side. In a mixed mode, with 5V GPIO ports but connected to a 3.3V Microcontroller, you supply 5V to VDD but leave the VCC-VDD jumper open.
Library and code samples, for example for Arduino, is available and easy to find (search engine).
Supply voltage: 2.5 – 5.5V
Output current: 100mA combined (max. 20mA per channel)
Output current source: 1mA max.
Output current sink: 25mA max.