# How can I calculate the power dissipation of an IC from datasheet values?

I have to make a circuit using ICs on a PCB. But before that, I want to calculate power dissipation of IC. So, I saw datasheet of 7400, and it gives me an input voltage, supply voltage, input current and output current. But I can't recognize what is needed for the calculation. How can I calculate power dissipation? Or is there other information I have to know?

• For CMOS devices, see this FAQ.
– CL.
Commented May 20, 2020 at 18:27

Generally, the power dissipation of each IC is based on the product of its supply voltage, VCC and their supply current, ICC.

• thank you! I'll try it
– Guk
Commented May 21, 2020 at 11:57
• That generally only accounts for static current draw. The I/O load is unknown from OP's question (the output driving another CMOS IC input is a lot different power-wise than say a 50-ohm load). There is also a power component determined by the frequency that the output changes and the load capacitance. Commented May 21, 2020 at 18:20

You need more information. Parameters such as source impedance of the circuit driving the 7400, frequency of the input signals, and the load impedance are all going to affect the power consumption of the device.

• I want to compare with two circuit with same condition.
– Guk
Commented May 20, 2020 at 17:18
• Can I compare power dissipation with IC in two circuits under the same conditions?
– Guk
Commented May 20, 2020 at 17:19
• Not sure I understand what you are asking. 2 circuits but same conditions? Are the circuits exactly the same? You can compare power by measuring current into the Vcc pin of each circuit. Commented May 21, 2020 at 18:22