Please identify this old schematic symbol.

Discussion in 'General Electronics Chat' started by Envergure, Jun 14, 2011.

  1. Envergure

    Thread Starter Member

    Jan 14, 2010
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    These funny transistors are from the datasheet for the ICL8038, an obsolete function generator IC.

    What are they?
     
  2. Ron H

    AAC Fanatic!

    Apr 14, 2005
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    Those are NPNs with Schottky diodes from base to collector (diode anode to NPN base). The diode in this configuration is called a Baker clamp.
    A saturated BJT has phenomenon called excess base charge. The transistor cannot be turned off until that charge is removed. A Baker clamp prevents deep saturation, reducing the amount of excess base charge. Baker clamps are used in circuits that need fast switching transistors.
     
  3. atferrari

    AAC Fanatic!

    Jan 6, 2004
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    I seem to recall them somehow related to TTL or it was DTL? Not sure really...

    Most probably TTL inputs (?)
     
  4. Ron H

    AAC Fanatic!

    Apr 14, 2005
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    TTL 74Sxx and 74LSxx, among others. Scroll down to page 4 on the TI 74XX04 datasheet.
     
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