I'm trying to figure out how much power I can expect my ATTiny84 to use in idle mode and I'm not sure which of the two graphs from the datasheet I should use, or why there are two in the first place. I intend to run it at a clock speed of 1MHz and off of a 3V battery. Also, if I choose to run it using an 8MHz crystal with CKDIV8 set (so the clock speed is 1MHz), should I read the graph at 8MHz or 1MHz?
The top image is when using an external clock source and does not include any current used by that external clock source
The bottom image is when using the internal RC clock source at 1MHz, using that circuitry draws some power,
If your using the internal clock source, you would be using the bottom graph.