[coreboot] LPCflasher Wiki Page

Peter Stuge peter at stuge.se
Tue Nov 25 03:36:34 CET 2008


Joseph Smith wrote:
> >> A series of 1K ohms resistors 250mW (1/4W) on data lines D0 - D6
> >> convert the signals from 5V to 3.3v needed by the flash chip.
> > 
> > This sentence and design is not so good.
> 
> Ok, how about this:
> A series of 1K ohms resistors 250mW (1/4W) on data lines D0 ??? D6
> convert the signals from 5V to 3.3v needed by the flash chip.

This is still a bad claim. A resistor limits current and nothing
else. Ignoring that will harm the rest of the circuit.


> Any excess voltage is shunted by diodes inside the 74HC244 to its
> 3.3V power rail.

Umm, it could just break the IC. Please have a look at the data
sheet again to confirm my fears. Going beyond absolute maximum
ratings is not a good idea. Please avoid such recommendations.


//Peter




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