Am 12.02.2014 um 10:16 schrieb Michael Mrozek:
Am Wed, 12 Feb 2014 07:39:33 +0100 hat "Dr. H. Nikolaus Schaller" hns@goldelico.com geschrieben:
Hi,
Is there a way we can estimate how much power our final PCB would need? Can we find out how much power the SoC itself uses (without all the EVM stuff around?)
Yes, according to the EVM Reference Guide (swcu130) secion 4.2 there are some 30 mOhm 0.5% resistors on the board so that we can measure the current at several places individually.
Okay... the I'll check the reference guide to see which ones I need to use tol test it.
Another idea is to break into U-Boot console and measure then. Most certainly it is running in single core low clock (300 MHz?) mode.
Hm, it uses 2W straight when I switch it on, doesn't sound like single core 300MHz...
U-Boot has no power management - except low CPU clock.
If I remember correctly my first experiment the whole EVM did draw ~400mA at 5V.
Same here, which would be the 2W in idling I was talking about.
It is the same as an OMAP3 (BB or GTA04 values) draws in idle mode. This means unless there is power management, the CPU enables all clocks for all system components. By switching off some parts it is possible to get it down to 150-200 mA.
You must go to "suspend" mode or an improved power management scheme to get below.
I'll do measurements for the Pandora today, to get some comparison values.
Yes, that would definitively help us to understand the figures.
One more thought about the TI tablet comparison. The panel backlight is drawing energy roughly proportional to the area of the display. So 2W for a 7 inch panel is quite typical.
BR, Nikolaus