The maximum operating frequency of the PCF8594C-2T/02,112 is 1.5 MHz.
The gain of the PGA can be configured by writing to the Gain Control Register (GCR) using the I2C interface. The gain can be set to 1, 2, 4, or 8.
The input impedance of the analog inputs of the PCF8594C-2T/02,112 is typically around 10 kΩ.
Yes, the PCF8594C-2T/02,112 can be used as a standalone ADC. It has a built-in ADC that can convert analog signals to digital signals.
The PCF8594C-2T/02,112 has a power-down mode that can be enabled by writing to the Power-Down Register (PDR) using the I2C interface. This reduces the power consumption to a minimum.