Benefits & Issues of Migrating 5-V and 3.3-V Logic to Lower-Voltage Supplies (Rev. A)

In the last few years, the trend toward reducing supply voltage (VCC) has continued, as reflected in an additional specification of 2.5-V VCC for the AVC, ALVT, ALVC, LVC, LV, and the CBTLV families. In this application report, the different logic levels at VCC of 5 V, 3.3 V, 2.5 V, and 1.8 V are compared. Within the report, the possibilities for migration from 5-V logic and 3.3-V logic families to 2.5-V VCC are shown, and the implications of the reduced supply voltage are discussed. Data is provided that shows the influence of reduced VCC on power consumption, drive capability, and propagation delay time for the logic families. Further, the requirements for an overvoltage tolerance (5-V/3.3-V input and output) is discussed, as well as interfacing opportunities in a mixed-mode environment in which two different supply voltages are used. This application report is intended to be used as a designer's guide to component selection and usage at supply voltages below 3.3-V. The data in this document is typical data taken under typical laboratory conditions (25 degrees C) and 2.5-V or 1.8-V, except where otherwise noted. The data is intended as a design guideline only.