GSM power usage / standby time
wally.ritchie at gmail.com
Thu Nov 15 17:38:40 CET 2007
On Nov 15, 2007 10:47 AM, Erland Lewin <erland at lewin.nu> wrote:
> I was looking at the power management page on the OpenMoko Wiki, which
> says that the GSM part draws 45 mW when idle but connected (that's for
> the GTA01, but I think the GTA02 has the same GSM chipset), and that the
> battery capacity after power supply losses is 3.5 Wh. This would give a
> theoretical maximal standby time of about 3 days (in practice lower
> because I guess things like RAM refresh will use power too).
In GSM idle mode the power consumption should be < 10mW from the
modem. This is based on similar devices using this chipset.
If all other devices are off or suspended, then the only other thing running
would be SDRAM self-refesh and the PMU, both of which are minimal.
That being said, we still seem to be a long way from fully working
suspend/resume which would put the modem in low power state as well as
all other devices.
BT is of the same order, about 10mW in suspend (able to respond to other
devices). But the BT low power states are problematic with the current hardware.
> This sounds low to me. I googled other phones using the Nokia BL-5C
> battery, and found for instance the Nokia 3100 which has an advertised
> standby time of 410 hours (17 days) with an 850 mAh battery.
> Are the figures on the OpenMoko wiki correct, and if so, why is the
> Neo1973 GSM standby power consumption so much (>5 times) higher than
> other phones'?
Power Management on mobile devices requires careful attention to details at
the design stage and verification of all elements including both hardware and
software. These were apparently not done at the proper time in lieu of more fun
stuff like getting games and videos and every linux app known to man to run on
the device ;). PM shortcomings probably relate to the same design processes
that resulted in a quad-band phone that works on three bands.
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