Connecting 3,3V uC and sim900 4V

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Hi !

 

I have uC  which runs on 3,3V but could also handle 3,6V.

 

Sim900 runs from 3,6-4,5V.  When transmitting voltage drops for about 0,4V, so sim900 should have at least 4,0V.

 

Connection between uC and sim900 is serial and what I need is voltage level translator  3,3V <=> 4V.

 

 

Thank you !

 

Best regards !

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The SIM900 PDF says supply voltage 3.4V - 4.5V

So you could run SIM900 and MCU @ 3.4V

 

If you are determined to use 4.0V and 3.3V you can use series resistors to cope with level-translation.

Both I2C and SPI will work quite happily with hi=3.3V on the 4.0V device.

 

You could use buffer chips but it is hardly worth it.    But they would be preferable if you want minimum current from a battery.

 

David.

 

 

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I have the same issue , can i continue this discussion or start a new one?

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while(!solution) {patience--;}

Last Edited: Tue. Jul 7, 2015 - 07:03 AM