The HEF4028B is a 4-bit BCD to 1-of-10 decoder. A 1-2-4-8 BCD code applied to inputs A0 to A3 causes the selected output to be HIGH, the other nine will be LOW. To use as a 1-of-8 decoder with enable, 3-bit octal inputs are applied to inputs A0 , A1 and A2 selecting an output Y0 to Y7 . Input A3 then becomes an active LOW enable, forcing the selected output LOW when A3 is HIGH. The device may also be used as an 8-output (Y0 to Y7) demultiplexer with A0 to A2 as address inputs and A3 as an active LOW data input. Inputs include clamp diodes. This enables the use of current limiting resistors to interface inputs to voltages in excess of V_DD.