Simple power cunsumtion question

Basil

Hi All,

Just confirming something.
Trying to determine MAX power consumption by the Prop operating at 4MHz.

Using '500 μA per MIPS (MIPS = Freq in MHz / 4 * Number of Active Cogs)' from the Manual...

At 4MHz using all 8 cogs running spin, current draw should be 4mA right?

Is there anything else (aside from current draw on the IO pins) which would increase consumption?
Also, when the bit above says 'Freq in MHz', is the MHz before or after the PLL?

Thanks All.

heh, just noticed it works out at 1mA per MHz when running 8 cogs

Mike Green

1) The 'Freq in MHz' is after the PLL. The current draw depends on the clock speed of the processors and memory

2) There's probably some small additional current draw for the cog counters and the 500ua/MIPS is an approximation. I don't know how many devices they've tested nor how many measured points on the curve they have. Check out the datasheet in the downloads section for the Propeller. There is probably some temperature variance as well.

Basil

1) I thought as much, just wanted to be sure [noparse]:)[/noparse]
2) Oooo a datasheet! Ok, so it pretty much matches up with my first assumption. I will say 6mA to cover everything.
I will not be using a PLL, just a 4Mhz crystal.

Thanks Mike