PCF8591 is a single-chip, single-supply low-power 8-bit CMOS data acquisition device with a serial I2C-bus interface, 1 output signal and four analog inputs. Three address pins A0, A1 and A2 are used for programming the hardware speech, allowing the use of up to eight devices linked to the I2C-bus without additional hardware. Data, control and address to and from the device are transferred serially via the. The functions of the device include analog input multiplexing, on-chip track and hold operate, conversion and an 8-bit digital-to-analog conversion. The maximum conversion rate is provided by the speed of the I2C-bus.