I see the TPS2051 in the USB Host section of the schematic, but it is fed 
from SYS_5V. Isn't that _after_ the TPS65217C shuts everything off when the 
input voltage exceeds an average of 6V? 

I guess if you're being absolutely proper, the 2051 says 6.0V absolute max 
and the 65217 says it limits to a max of 6.4V even though 6.0V is typical. 

But the 2051 says output voltage range is -0.3 V to V(IN) + 0.3 V, so the 
internal transistor must be able to handle at least 6.3V...  And I'd be 
amazed if they couldn't handle far more unless they are trying to feed a 
current overload - from which they should protect themselves. Seems like 
since these are both TI products, they'd be designed to work together?  

So my real question - do you actually see these frying in the real world? 


On Thursday, December 5, 2013 6:38:01 PM UTC-8, Gerald wrote:
>
> And if you go to 6V, it will blow up the power control switch for the USB 
> host, rated at 5.5VDC maximum. 
>
> Gerald
>
>
>
> On Thu, Dec 5, 2013 at 8:27 PM, <[email protected] <javascript:>> wrote:
>
>> Just dug into this... My notes:
>>
>> BBB Power: 
>> No onboard input voltage regulation! Input jack connects directly to 
>> TPS65217C PM IC. 
>>
>> From tps65217c.pdf:
>> -----
>>                                Absolute Maximum Supply voltage range, 
>> USB, AC: -0.3 to 20 V
>> RECOMMENDED OPERATING CONDITIONS - Supply voltage, USB, AC: 4.3 to 5.8 V
>>                                                             Maximum Input 
>> current from AC: 2.5 A
>>                        VIN(OVP) Input over voltage detection threshold 
>> USB, AC: 5.8 (typ)6 (max)6.4 V
>> provides a linear battery charger for single-cell Li-ion and Li-Polymer 
>> batteries... 
>> -----
>>
>> The 5V rails VDD_5V and SYS_5V go to the LEDs, the expansion connector, 
>> the DVI/HDMI connector, and the USB connectors. Unless you are using these 
>> for something which needs regulated +5V, the wider 4.3 to 5.8 V limits will 
>> keep the board itself happy. 
>>
>> It will safely disconnect from an input that exceeds about 6V, and can 
>> then handle up to 20V. But it is _not_ protected from reverse polarity! 
>>
>>
>>
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