Am Do 28. August 2008 schrieb Andy Green: > Somebody in the thread at some point said: > > | Charger Overshoot Voltage VCHGR_OVRSHT 6.0 V max. > | ----- > | > | Though we couldn't even attach a USB-charger compliant to this spec, > as it has > | to be equipped with micro-USB plug, we should expect to see voltages on > | USB-receptacle of up to 6.0V AT LEAST. > > Why? Our charger doesn't follow that spec that mentions 6.0V. > > | I think it's a strong argument for additional OVP extending our actual > | abs.max.rating of 5.5V to limits safely beyond 6.0V, like we are actually > | about to do for GTA03. > > Regulator and cap in the charger should mitigate this. Why don't we > measure our actual charger performance in this case, shouldn't be too hard.
For one simple reason: USB-charging was meant to work with *any* USB-charger (otherwise we would have used ID-pin for VDD of charger ;-) and Neo wouldn't take any power from USB-VBUS, thus no issue with OVP), and for sure we don't want to restrict customers to usage of OM-wallwart-powersupply only. We wouldn't even get away with this, legally. As long as our device has a USB-receptacle, it has to cope with insertion of what a customer can reasonably assume should work when attached to it. Then we also got the *wide* field of externally powered hubs. Ever had a look at the way those are providing power to downstream-connectors? And at the power-supplies that are (or are not!) shipped with these hubs. "Dear customer! There are a plethora of powered USB-hubs out there. We strongly recommend NOT to attach Neo to any of those, as we didn't care to protect the device against voltages that may be found on a lot of the cheaper ones you might incidentally use. Please connect Neo to the original charger or certified good hosts only!" :-( Do we really need more reasons to care about that issue? cheers jOERG
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