(a) Calculate the following (show work): (LO 1-14) DCNM AB (LO 1-14) DCNM BA (LO
ID: 2247996 • Letter: #
Question
(a) Calculate the following (show work):
(LO 1-14) DCNM AB
(LO 1-14) DCNM BA
(LO 1-20) Practical Fanout AB
(LO 1-20) Practical Fanout BA
(b) Draw the circuit and calculate the value of the current limiting resistor for a Type “A” gate driving an LED to the maximum brightness possible in a current sourcing configuration. Assume VLED is 1.5V. (LO 1-21)
(c) Draw the circuit and calculate the value of the current limiting resistor for a Type “B” gate driving an LED to the maximum brightness possible in a current sinking configuration. Assume VLED is 1.5V. (LO 1-21)
2. Assume two logic families have the following D.C. characteristics: Logic Family "A” Logic Family "B”Explanation / Answer
(b) Draw the circuit and calculate the value of the current limiting resistor for a Type “A” gate driving an LED to the maximum brightness possible in a current sourcing configuration. Assume VLED is 1.5V. (LO 1-21)
(c) Draw the circuit and calculate the value of the current limiting resistor for a Type “B” gate driving an LED to the maximum brightness possible in a current sinking configuration. Assume VLED is 1.5V. (LO 1-21)
Ans:
Noise Margin A B = ( NMH + NMH )/2
= ((VOHA - VIHB) + (VILB - VOLA )) / 2
= ((4.2 - 2.45) + (2.45 - 0.45) )/2
= (1.75 + 2) /2
= 1.875
Noise Margin B A = ( NMH + NML )/2
= ((VOHB - VIHA) + (VILA - VOLB )) / 2
= ((3.7 - 3.60) + (1.60 - 0.37))/2
= (0.10 + )/2
= 0.665
FanOut A B = min( (Iout high A / Iin high B) ,((Iout low A / Iin low B)))
= min ((8mA/0.042mA),(8mA/0.42mA))
= min (190,19)
= 19
FanOut B A = min( (Iout high B / Iin high A) ,((Iout low B / Iin low A)))
= min ((0.550mA/0.0003mA),(8.5mA/0.00025))
= min (1833,34000)
= 1833
(b) RA = (VOHA - VLED) / IOHA = (4.2 - 1.5)/ 8mA = 337.5 Ohm.
(c) RB = (VOHB - VLED) / IOHB = (3.7 - 1.5)/ 0.550 mA = 4K Ohm.
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