74HC147 Decimal-to-BCD Priority Encoder IC (SMD Package)

Where the 74HC138 decoder also in the catalog expands a few select lines out into many outputs, the 74HC147 does the opposite job, taking up to 10 individual decimal input lines, say from a bank of switches or a keypad, and compressing whichever one is active down into a compact 4-bit BCD code. That priority-encoding function cuts down dramatically on the microcontroller pins needed to read a wide input bank, handling the encoding in hardware instead of software.