CMOS and LVTTL Voltage Levels


Joined Feb 19, 2009
As you move to the right, you'll see the top of the chart is 3.3V. 2.5V Logic, such as Microchip's published minimum operating voltage on some microcontrollers, is a difficult voltage to interface with externally, as 2.5v is considered High or indeterminate value on 3.3V logic, and low or indeterminate on 5V CMOS.

The far right represents most "low voltage" implementations, as percentages of Supply voltage, which can be applied from 2V to 3.5V

Today's x86 and x64 CPUs run at 1V-1.25V Vdd, and their logic isn't as standard as the chart above, internal to the die, except for the slower external signals, the levels only need to meet the proprietary internal standards of the CPU.