Many applications use single or multiple LEDs. These include 7-segment displays and single indicators as well as arrays of LEDs that form grids or panels. To drive these LEDs, 5 V serial input parallel output shift registers are commonly used. Solutions such as the 74HC595 are used as input output expansion. They allow a microcontroller to control eight LEDs using three of its control pins. Serial data is applied to the serial input of the shift register and clocked in via the input clock. Once the 8-bit shift register is loaded, the output clock applies the data to the storage register and the outputs. External drivers controlled by the 74HC595 then activate the corresponding LEDs.