I have a question regarding calculation power consumption of a circuit. I have a rather large circuit that I am trying to figure out the total power consumption for. My question is how do you calculate the consumption of each device, realizing that P=VI? For example, take a schmitt trigger that is being supplied with 3.3 V. Would I calculate the estimated power consumption by taking the Icc supply current and multiplying it by Vcc? Alternatively, do I take the output current and multiply it by the output voltage? My reason for doing this type of analysis is to decide if the power supply that I am using for all of my circuits is sufficient.

Thank you in advance for any help.

 

Sounds like time to hit the data sheets. They should have some figure for each IC for Icc (supply current). There may be a typical figure, and one for max. If you want a bulletproof supply, use all the Icc max numbers to get total worst-case supply current.

If you want an eye-opener, compare supply current for 74xx TTL with any of the CMOS families.

 

Keep in mind that will be the static power consumption and during transitions you will be briefly using more. If it is being clocked this will become a consistent power draw.