totem pole output

Discussion in 'General Electronics Chat' started by yassser, Feb 8, 2013.

  1. yassser

    Thread Starter Member

    Jul 25, 2011
    91
    0
    hello,

    does totem pole output stage(push pull) need a current limiting resistor to limit the current to the maximum allowed current , or does it limit the current anyway , I notice that when I connect it to a a small resistance load directly by mistake , it doesn't get burned , while it does in the case of open collector output .
     
  2. chuckey

    Well-Known Member

    Jun 4, 2007
    75
    10
    A standard totem pole output (TTL) has a low value resistor in series with "top" transistor and Vcc and yes , its small, otherwise they could not get in the package :).
    Frank
     
  3. Audioguru

    New Member

    Dec 20, 2007
    9,411
    896
    A 555 oscillator/timer IC has a totem pole push-pull output.
    It has nothing to limit the current to its maximum allowed 200mA.
    But when the output switches high or low it causes a shoot-through current surge of 400mA.
     
  4. BillO

    Well-Known Member

    Nov 24, 2008
    985
    136
    Some do and some don't. What device are you talking about?
     
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