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Per Westermark
08/03/12 18:56
Read: 438 times
Sweden


 
#187993 - Same for ARM
Responding to: Jim Granville's previous message
It started with multiple VCC voltages, but now many ARM chips too have internal DC/DC converters to allow the core to get a lower voltage internally while the external VCC controls the I/O signal levels. Alas, most ARM solutions are still 3V3 for external pins, making it much harder to get good overvoltage protection on ADC inputs without affecting linearity. And requiring sometimes more expensive MOS-FET transistors. Or sometimes requiring the I/O pin to switch between input and output, so it basically tri-states with a 5V pull-up.

Bigger chips normally have two VCC voltages because of the larger current needed to the core. But then the cost of the bigger chip is also a bit higher so extra cost of a separate voltage regulator doesn't matter as much. Requirements for an embedded Linux platform isn't the same as requirements for a design with basically just a single microcontroller and a bit of external glue.

List of 13 messages in thread
TopicAuthorDate
CPLD level translators      Mahmood Elnasser      05/15/12 03:42      
   TI Voltage level translators ?        Jim Granville      05/15/12 05:27      
      thanks      Mahmood Elnasser      05/16/12 01:03      
      Why specifically CPLD?      Andy Neil      05/16/12 15:17      
         True      Mahmood Elnasser      05/16/12 22:45      
            Perhaps certain CPLD's would do the job      Richard Erlacher      08/01/12 16:14      
               Wide Vcc CPLDs sadly rare      Jim Granville      08/02/12 15:09      
                  forgive my ignorance, but ...      Richard Erlacher      08/02/12 17:54      
                      some examples      Jim Granville      08/03/12 15:11      
                        Same for ARM      Per Westermark      08/03/12 18:56      
                           some small devices have OCR too      Jim Granville      08/03/12 23:14      
                              Bigger chips      Per Westermark      08/04/12 05:59      
            Altera FPGAs        Oliver Sedlacek      08/06/12 04:07      

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