TTL, 5 V CMOS and LVTTL Levels

Colors

Dark gray

Noise margin

Light gray

Transition range, low and high levels are unspecified

Voltage levels

V_OH

Minimum high-state voltage @driver output

V_IH

Minimum high-state voltage @receiver input

V_t

Threshold level, typically at the middle of the transition range

V_IL

Maximum low-state voltage @receiver input

V_OL:

Maximum low-state voltage @driver output