What is the major problem faced in DFT with tri-state buffer

SCAN, Boundary SCAN, MBIST, ATPG, JTAG, ATE, DFT simulations.
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Arvind
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Location: Noida, India

What is the major problem faced in DFT with tri-state buffer

Post by Arvind » Wed Apr 09, 2014 10:31 pm

What is the major problem faced in DFT with tri-state buffers and how is it resolved?

RENU
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Joined: Mon Apr 07, 2014 11:18 pm

Re: What is the major problem faced in DFT with tri-state bu

Post by RENU » Mon Apr 14, 2014 6:06 pm

Tri-state buffers are generally used for bidirectional IO's or to drive sharing buses . Chip Select (CS) of memories is an example. Tri-state buffer can be represented as : bufif0(PAD , I ,OEN) , bufif1(PAD , I ,OEN) .

Issues with tri-state buffer :-

1. Probability of contention :- Bus contention occurs when two drivers forces opposite value onto tri-state bus.
2. Output as High -Z :- If tri-state buffer select line is not controlled properly then it can result output in high -Z state and hence effectively removing the output from the circuit.

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