The D/A converter converts digital or binary data into its equivalent analog value. The input digital data for a D/A converter is an n-bit binary word D. The bit b_{1} is called the most significant bit (MSB) and bit b_{n} is the least significant bit (LSB). Then, the quantity D can be represented by

D = b_{1}2^{-1} + b_{2}2^{-2} + b_{3}2^{-3} +…+ b_{n}2^{-n}

The D/A converter accepts the binary input D and produces an analog output, which is proportional to D using a reference voltage V_{R}. The converted analog value is either in voltage or current for. For a voltage output D/A converter, the conversion characteristics may be expressed as:

V_{o} = KV_{FS} = KV_{FS}(b_{1}2^{-1} + b_{2}2^{-2} + b_{3}2^{-3} +…+ b_{n}2^{-n})

Where,

V_{o} = output voltage

V_{FS} = full-scale range of voltage

K = scaling factor, usually unity

b_{1}…b_{n} = n-bit binary fractional word with binary point located at the left.

b_{1} = most significant bit (MSB) of weight V_{FS}/2

b_{n} = least significant bit (LSB) of weight V_{FS}/2^{n}