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Explanation of Overdrive term?

Discussion in 'The Projects Forum' started by aina, Jan 18, 2012.

  1. aina

    Thread Starter New Member

    Aug 22, 2011
    I want to know what is meant by Overdrive Base Voltage in Bipolar Junction Transistor Terms?
  2. mcasale

    Senior Member

    Jul 18, 2011
    If you are trying to turn on a BJT, and really want the device to go into saturation, you want to drive the BASE with more current than you think you'll need.

    For example, if the load on the COLLECTOR requires 100mA, the BASE current needs to be 100mA/BETA, at least. Once in saturation, BJT BETAs go way down. I always assume a minimum BETA of 10, unless the spec sheet gives you a better number.

    As always, watch out for total device power dissipation.