SIMtrace prototype bug report

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Sylvain Munaut 246tnt at gmail.com
Sun Jun 19 16:54:35 UTC 2011


>> > However, I think there's one pretty serious problem in the hardware
>> > design:  The bus switch has something like at least 5 (rather 16Ohms) of
>> > internal 'on' resistance between the sim card and the phone.  While this
>> > _might_ still work for I/O, nRST and CLK lines, it definitely doesn't
>> > fly for the supply voltage (VCC).

Why not just keep the bus switch IC for the signals. ( ~ 20 ohms won't
be a problem for sure ).

And use any PMOS with a pullup for the VCC switching ?  Or you can
even get fancy and use a dedicated load switch like the TPS22960 .

Cheers,

     Sylvain




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