The PCF8591 is a single-chip,single‑supply low‑power 8‑bit CMOS data acquisitiondevice with four analog inputs,one analog output and a serial I²C‑bus interface.Threeaddress pins A0,A1 and A2 are used for programming the hardware address,allowingthe use of up to eight devices connected to the I²C‑bus without additional hardware.Address,control and data to and from the device are transferred serially via the two-linebidirectional I²C‑bus.

The functions of the device include analog input multiplexing,on-chip track and holdfunction,8-bit analog‑to‑digital conversion and an 8‑bit digital‑to‑analog conversion.Themaximum conversion rate is given by the maximum speed of the I²C-bus.