3.3v to 5v level translation

Discussion in 'The Projects Forum' started by garch, Dec 14, 2009.

  1. garch

    Thread Starter Member

    Aug 23, 2008
    24
    0
    Hi,

    I would like to use a 3.3v parallax propeller microcontroller to drive a large high torque Futabo servo. I wanted to know:

    (1) How to perform a 3.3v to 5v level translation (e.g. like a MAX3000 IC)
    (2) How to drive such a high load (e.g. 1A @ 5v) from the microcontroller.

    Any help would be greatfully appreciated.

    Thanks

    Garch
     
  2. Papabravo

    Expert

    Feb 24, 2006
    10,148
    1,791
    The best solution that I have found is devices that work with Vcc from 1.65V to 5.5V and have TTL thresholds. So a 5V signal driving a device with Vcc at 3.3 Volts will define a low as less than 0.8V and a high as greater than 2.0V and will be toleraant of 5V on its input.

    Similarly a device with Vcc at 5V will define a low as less than 0.8V and a high as greater than 2.0V.

    For driving higher current loads you can use a BJT or a logic level MOSFET. Each method has advantages and disadvantages.
     
  3. THE_RB

    AAC Fanatic!

    Feb 11, 2008
    5,435
    1,305
    The Futaba servos should work fine with control pulses of 0v-3v. So you can control it direct from the microcontroller pin.

    As for the 1 amp power wire to the servo, just put a switch on it or connect it direct to the battery etc. When the microcontroller stops sending control pulses the servo will shut down and only draw about 7mA or so from the supply.
     
  4. garch

    Thread Starter Member

    Aug 23, 2008
    24
    0
    Many thanks.
     
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