USB-OVP

[silver62]

Hi,
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?

Regards,

Silvestro


Joerg Reisenweber wrote:
> 
> FYI:
> 
> From http://www.usb.org/developers/devclass_docs/batt_charging_1_0.zip
> 
> -----
> Battery Charging
>     Specification
>          Revision 1.0
>           Mar 8, 2007
> 
> p.19:
> If the current drawn from a USB charger changes suddenly within the range
> of 
> 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.
> 
> p.23:
> 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.
> 
> 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.
> 
> cheers
> jOERG
> 
>  
> _______________________________________________
> hardware mailing list
> hardware at lists.openmoko.org
> http://lists.openmoko.org/mailman/listinfo/hardware
> 
> 

-- 
View this message in context: http://n2.nabble.com/USB-OVP-tp790003p1394138.html
Sent from the Openmoko Hardware mailing list archive at Nabble.com.