Why is there a difference in the power consumption calculation between the Excel sheet and the Device Configurator?

FAQ #101398

 

Problem
A configuration calculated with the old Excel sheet did not have the same current limitation for the CPUs. The same configuration is maybe rejected by the Device Configurator.

Reason
The reason is, that the maximal current on the V+ is depending on the charge on the 5V power supply. The Excel sheet did not take care of this dependency. This was leading to problems in very few cases. In the Device Configurator this dependency is added to the calculation. Means that each module that charges the 5V, has as well an influence on the maximal current on the V+. Due to this reason a configuration that was declared with the old Excel sheet as o.k can now fail, when configuring it with the Device Configurator.

Solution
We recommend using the Device Configurator. If you are very close to the limit it can be sufficient to have a better power supply. If your power supply has a tolerance of -10/+10% this could be enough to guarantee the configuration to work. More informations about different Power Supplys can be fount in the PCD3 manual chapter 3.2