C5535 power consumption

The main factors for the power consumption of CMOS devices

Dynamic power consumption

The two main factors that affect the dynamic power consumption of CMOS devices are switching frequency (f) and operation voltage (V). The dynamic power dissipation of a CMOS circuitry can be calculated by following equation:

Here

C is the capacitance load

V is the operation voltage

f is the operation frequency

Based on the equation, the dynamic (or active) power is proportional to the square-of-the-V, and. So an optimized the system design means we should set the DSP working at a state, in which the active frequency/voltage will meet the application performance requirements; and meanwhile not over clocking the devices, or applying higher voltage that it needs.

Static power consumption

The static power consumption consists of the leakage of a CMOS device, the IO configuration of the device.

 Hope this information helps:

Regards

 Vasanth

Also to add :

Since most gates do not operate/switch at every clock cycle, they are often accompanied by a factor , called the activity factor. The dynamic power dissipation may be re-written as .

Active power is what is consumed by the active parts of the DSP. These include the CPU, peripherals, and I/O pins associated with the peripherals. The active power consumption is based on the supply voltages, operating frequency, and how each peripheral is configured.

The parameters used to describe each module activity are:

• Frequency is the operating frequency of a module or it is the operating frequency of the interface to that module.
• Idle Status indicates whether the module is in idle or in active state.
• %Utilization is the percentage of activity in a module relative to its maximum.

Dear all, 

Thanks for your messages.

According to your relationship P = CV²f, with f the CPU clock frequency, not its utilization.

Let's say my CPU frequency is 100 MHz @ 1v3.

If my main program is while(1){} without any ISR neither peripherals, I assume that the power consumption will be the same any other main program "making some stuff (loop, add, ...).

In the fist one, CPU utilization in 0%, in the second case, CPU utilization is not 0%

So how the CPU utilization is related to power consumption assuming the same peripheral usage ?

Thanks.

Nicolas