The maximum operating frequency of the PCF8594C-2T/02,118 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 input channels of the PCF8594C-2T/02,118 is typically around 10 kΩ.
Yes, the PCF8594C-2T/02,118 can be used as a standalone ADC. It has a built-in ADC that can convert analog input signals to digital output codes.
The PCF8594C-2T/02,118 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.