What is single fault protection??

Discussion in 'General Electronics Chat' started by rakeshm55, Jan 13, 2011.

  1. rakeshm55

    Thread Starter Member

    Oct 19, 2010
    I have seen some boards having two resistances connected in parallel driving the base of H- Bridge transistors....

    ---- parallel resistors ---- transistor base ...

    Someone suggested it is single fault protection....
    What is it?? any article on their functinality....
    Is that the purpose of those resistors....
  2. ifixit

    Well-Known Member

    Nov 20, 2008
    Sometimes resistors are doubled up in series, or parallel to get a more precise value, or better power rating.
  3. timrobbins

    Active Member

    Aug 29, 2009
    Yes, for transistor bases the designer could have either power rating or redundancy in mind - but I suggest power rating, which could be to allow the resistor to survive failure of other parts, or could be because they already use that lower power resistor on the pcb and it is more cost effective to use two of them than to source and store a new part.

    Ciao, Tim