- Figure Q 5 A And Figure Q 5 B Show The Block Diagram And The Logic Diagram Of A 74293 Integrated Circuit Chip Respecti 1 (40.4 KiB) Viewed 24 times
Q5 DIGITAL ELECTRONICS
Figure Q.5(a) and Figure Q.5(b) show the block diagram and the logic diagram of a 74293 integrated circuit chip respectively. CP₁ 16 CPI J K CLR MR₁ MR₂ CP₁ CP⁰ K 2 Vcc (14) (11) (10) MR₂ MR₁ CLR (13) (12) (8) (4) (5) (9) (7) Q3 Q₂ Q1 Qo GND Figure Q.5(a) K 3 Figure Q.5(b) CLR J K CLR All the J and K inputs are connected to logic 1. Q3 is the most significant bit.
(a) (i) The chip is connected as in Figure Q.5(c). Analyze the circuit and write its sequence starting from Q3Q₂Q1Q0 - 0000. = CP₁ CPo nn Vcc (14) (11) (10) MR₂ MR₁ (13) (12) (8) (4) (5) (9) (7) Q3 Q2 Q₁ Qo GND Figure Q.5(c) [5 marks] [CO3, PO2, C4] In the course of connecting the circuit in the digital laboratory, pin 10 of the chip broke off. Can you still use the chip to count the sequence in (i), or do you have to get a new chip from the technician? Explain. [5 marks] [CO3, PO2, C4] (b) If the circuit is connected as in Figure Q.5(d), the counter counts different sequence from part (a)(i). Explain why and determine the sequence. [4 marks] [CO3, PO2, C4]
(c) (d) CP⁰ CP₁ Vcc (14) (11) (10) MR₂ MR₁ 5 (13) (12) (8) (4) (5) (9) (7) Q3 Q2 Q1 Qo GND Figure Q.5(d) The chip was designed as an up-counter. With minor modifications to its internal structure, the chip can function as a down-counter. Suggest 2 possible modifications. [4 marks] [CO3, PO2, C4] This chip is not popular with consumers. What could be the technical reason for this? [2 marks] [CO3, PO2, C4]