Improved power-down for the 8051

Members of the 8051 family of microcontrollers (MCS51) are well-known and widely used. The controllers have a powerdown mode in which the program processing is suspended by the clock oscillator and ended with a power-down instruction. To reduce the current drain, the supply voltage is reduced to a minimum of 2 V after the powered-down mode has been selected. This mode can only be disabled by a reset, for which the supply voltage needs to be returned to 5 V.