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3.3V Chip in a 5V Project — Parallax Forums

3.3V Chip in a 5V Project

Scott4Scott4 Posts: 45
edited 2009-12-23 18:19 in Accessories
The only chip I could find to complete my project was 3.3V. The rest are 5V. Will I need another power supply? What about the signal levels? -Scott

Comments

  • MacGeek117MacGeek117 Posts: 747
    edited 2009-12-23 02:55
    If you put 10k resistors on all of the interfaces between the two levels, your circuit should work fine.
    MacGeek117

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  • FranklinFranklin Posts: 4,747
    edited 2009-12-23 04:34
    What chip?

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  • Mike GreenMike Green Posts: 23,101
    edited 2009-12-23 05:16
    Yes, you will need a 3.3V power supply for the chip. A simple low-dropout fixed regulator to drop the 5V to 3.3V will do. Regarding the signal lines, it depends on the chip. Some 3.3V chips have 5.0V tolerant inputs and could be directly connected to the rest of the circuit. Some 3.3V chips do not and you'd need some kind of level conversion. Outputs might be able to be used as is. Inputs might just need a series resistor like 2.2K or greater. There are some cases where you'd need a level conversion chip of some sort.
  • LeonLeon Posts: 7,620
    edited 2009-12-23 18:19
    Further to what Mike said, you need to check the data sheets carefully for acceptable voltage levels for the signals if you aren't using level converters.

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