sfimiani at hotmail.com
Wed Oct 29 17:16:29 CET 2008
why there is a requirement for VCHGR_UNDSHT < 4V? If the voltage of charger
fall below 4V when the charger is connected for 2 ms is this a big issue?
Joerg Reisenweber wrote:
> From http://www.usb.org/developers/devclass_docs/batt_charging_1_0.zip
> Battery Charging
> Revision 1.0
> Mar 8, 2007
> If the current drawn from a USB charger changes suddenly within the range
> 0mA to 500mA, then the
> transient voltage from a USB charger shall not go below VCHGR_UNDSHT.
> Under no
> circumstances shall the
> transient voltage of a USB charger exceed VCHGR_OVRSHT.
> Charger Overshoot Voltage VCHGR_OVRSHT 6.0 V max.
> Though we couldn't even attach a USB-charger compliant to this spec, as it
> to be equipped with micro-USB plug, we should expect to see voltages on
> USB-receptacle of up to 6.0V AT LEAST.
> 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.
> hardware mailing list
> hardware at lists.openmoko.org
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