Support and General Use > Hardware
Sansа Clip Zip - Improve battery life
saratoga:
I think the current build now shows all (about 20) voltage channels on the device.
Regarding pclk I don't mind to tell you what to use, but somewhere between 20-40 is likely optimal.
By the way one user testing the lower CPU clocks found that they break most formats other then flac. So if we want to lower them much frequency scaling will be needed.
saratoga:
Have you taken any measurements of AVDD17 or AVDD27? Looking at the voltages, we run AVDD17 a little higher because it determines the maximum headphone output. I was thinking raising it might be useful, but I won't do that if it uses a lot of power.
Edit: If I understand correctly, AVDD17 is the analog voltage used for almost everything but headphone amplifiers (line out, mixers, etc) while AVDD27 is the headphone output. I wonder if AVDD17 could be lowered since we do not use the line out.
Mihail Zenkov:
--- Quote from: saratoga on September 28, 2014, 03:53:55 PM ---By the way one user testing the lower CPU clocks found that they break most formats other then flac. So if we want to lower them much frequency scaling will be needed.
--- End quote ---
I also use it with mp3, but without any postprocessing. Frequency scaling should by next step.
--- Quote from: saratoga on September 28, 2014, 04:06:41 PM ---Have you taken any measurements of AVDD17 or AVDD27? Looking at the voltages, we run AVDD17 a little higher because it determines the maximum headphone output. I was thinking raising it might be useful, but I won't do that if it uses a lot of power.
--- End quote ---
I measure it at first - no significant difference at low volume. I don't test it at high volume. I try check it again.
--- Quote from: saratoga on September 28, 2014, 04:06:41 PM ---Edit: If I understand correctly, AVDD17 is the analog voltage used for almost everything but headphone amplifiers (line out, mixers, etc) while AVDD27 is the headphone output. I wonder if AVDD17 could be lowered since we do not use the line out.
--- End quote ---
When I try disable AVDD17 I don't hear any sound :) And save 1 mA - we can use this on pause, but not sure if it have sense.
Mihail Zenkov:
Checked - no significant difference at pause, low volume (-35dB) and high (0dB).
saratoga:
The volume mixers are still needed for playback, so AVDD17 can't be disabled. It might be possible to lower it (although that might require adjusting the volume mixer gains too to avoid clipping), but if it only uses 1 mA its probably not worth it.
AVDD27 is at 2.7v right now according to the A/D, so even if we raised it to its maximum of 3.3, that only gains ~ 1dB in maximum output. Maybe not worthwhile.
Testing CVDD2, it seems that PVDD1 is derived from it, and furthermore that the SD cards run off it, as 1.8v gives an ATA error trying to read storage :)
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