Hi Joerg,
> - Joerg suggests to add footprints for clamping Zeners on CD* > > - R14 through R16 don't make sense, particularly considering that we > may have a differential configuration. Instead, there should be > small caps (~47 pF) for RF filtering. > Current latest M1R4's audio schematic(page 1): http://downloads.qi-hardware.com/hardware/milkymist_one/sch/tmp/MILKYMISTONE.pdf A varistor is equivalent to two zerners and 1 capacitor, and since WM9707's analog supply recommended rate is 5V +10%*AVDD, i.e. 5.5V rating. Even current M1 is only designed at roughly 4.3V + 10%*4.3V = 4.73V To replace possibly proposed 47pF/C273~C277(CD-in & Line-in), I've checked: >From Panasonic varistor - http://industrial.panasonic.com/www-data/pdf/AWC0000/AWC0000PE4.pdf http://industrial.panasonic.com/www-data/pdf/AWC0000/AWC0000CE2.pdf Its EZJP("Low Capacitance" for DC to millions of HZ, PWR, SW, Audio terminals, etc.) series can be applied. Parameters as above, the candidate would be possessed of 0402, <= 47pF @1KHz, much less than 47pF@ 1MHz, so, p/n: EZJP0V080DA, 5.6V DC rating, varistor voltage 8V, 33pF typ.@ 1KHz, 22pF typ.@ 1MHz, contact discharge 8KV Do you think panasonic p/n above is suitable for us? Or we selected unqualified one? btw, this part doesn't show on Digi-key, so also picked a compatible AVR p/n: http://search.digikey.com/us/en/products/AVR-M1005C080MTACB/445-2559-1-ND/931227 Thanks a lot! - adam
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