Grendel wrote:I use a 2k2 resistor to 5V, works fine, uses less power. Shouldn't be a problem since you need a self powered device to met the specs for suspend. Leakage over the Zeneres is probably neglegtable if you use 3V6 ones.
Grendel wrote:Most (non OTG) hosts will do nothing if you draw 5-10mA during suspend tho.
Grendel wrote:Well, first, the 500uA are really only 300uA -- a host has 15k pull-downs on D- & D+, you get a 16.5k base load to Vterm; 200uA.
Grendel wrote:If you want timely wakeup you should only use Standby (note that INT0 can only be used as a level ISR) -- ~150uA if you also shut everything else down (BOD, AC, ADC ...)
Grendel wrote:An LDO is not only expensive (~$7, at least the one I looked at @ DigiKey), but also has a GND current of up to 200uA, 550uA already. Plus, you can't issue a remote wakeup to the host since you would have to get out of standby for that.
Grendel wrote:IMHO it's way too much a hassle to meet the specs. But if you do, let us know
spiff wrote:Grendel wrote:Well, first, the 500uA are really only 300uA -- a host has 15k pull-downs on D- & D+, you get a 16.5k base load to Vterm; 200uA.
That is new to me. What I don't understand is why they specify 500uA for the device if the host consumes some of that.
spiff wrote:But I'm getting sidetracked here. Can someone tell me what the requirements for the pull-up on D- is. As I see it, a pull-up to 5V is not the same as a pull-up to 3.3V. Perhaps this is the reason a 2.2K is fine when it pulls up to 5V?
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