第三章作业(答案)
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3.1 (a) 0 3.2 (a) 1 3.11 (b) 0 (c) 1 (d) undefined (e) undefined (f) undefined (g) 1 (h) undefined (b) 1 (c) 0 (d) undefined (e) undefined (f) undefined (g) 0 (h) undefined 功能表： ABCD 0000 0001 0010 0011 0100 0101 0110 0111 1000 1001 1010 1011 1100 1101 1110 1111 逻辑原理图： Q1 Off Off Off Off Off Off Off Off On On On On On On On On Q2 On On On On On On On On Off Off Off Off Off Off Off Off Q3 Off Off Off Off On On On On Off Off Off Off On On On On Q4 On On On On Off Off Off Off On On On On Off Off Off Off Q5 Off On Off On Off On Off On Off On Off On Off On Off On Q6 On On Off Off On On Off Off On On Off Off On On Off Off Q7 Off Off On On Off Off On On Off Off On On Off Off On On Q8 On Off On Off On Off On Off On Off On Off On Off On Off Z 1 0 0 0 1 0 0 0 1 0 0 0 0 0 0 0 3.21 High-state DC noise margin = VOHmin - VIHmin = 4.75 - 3.5 = 1.25 (V) Low-state DC noise margin = VILmax - VOLmax = 1.5 - 0.25 = 1.25 (V) 3.27 Vcc (b) VThev = Vcc×R2 / (R1+R2) = 5×330 / (330+270) Vin1 = 2.75V ISC = Vcc / R1 RThev = VThev / ISC = R1×R2 / (R1+R2) = 270×330 / (270+330) = 148.5Ω 74HC00 Vin2 Vo R2 330Ω Vcc R1 270Ω ∵VOHmin = 3.84V ∴ IOH = (VOHmin-VThev ) / RThev ≈ 7.3 mA > IOHmax = 4 mA ∵VOLmax = 0.33V ∴ IOL = (VThev - VOLmax) / RThev ≈ 16.3 mA > IOLmax = 4 mA 因此，超出了商用工作范围。 Vcc Vcc (d) VThev = Vcc×R2 / (R1+R2) = 5 / 2 R1 = 2.5V Vin1 470Ω Vo ISC = Vcc / R1 74HC00 RThev = VThev / ISC R2 Vin2 = R1×R2 / (R1+R2) 470Ω = 470 / 2 = 235Ω ∵VOHmin = 3.84V ∴ IOH = (VOHmin-VThev ) / RThev ≈ 5.7 mA > IOHmax = 4 mA ∵VOLmax = 0.33V ∴ IOL = (VThev - VOLmax) / RThev ≈ 9.2 mA > IOLmax = 4 mA 因此，超出了商用工作范围。 3.49 (a) 根据表3-10， 74LS的IOLmax = 8 mA，74AS的IILmax = -0.5 mA ∴ Low-state Fan-Out = 8 / 0.5 = 16 74LS的IOHmax = -400μA，74AS的IIHmax = 20μA ∴ High-state Fan-Out = 400 / 20 = 20 因此，总的最大扇出为16 高态剩余驱动能力 = (20-16)×20 = 80μA (b) 根据表3-10， 74LS的IOLmax = 8 mA，74F的IILmax = -0.6 mA ∴ Low-state Fan-Out = 8 / 0.6 ≈ 13 74LS的IOHmax = -400μA，74F的IIHmax = 20μA ∴ High-state Fan-Out = 400 / 20 = 20 因此，总的最大扇出为13 高态剩余驱动能力 = (20-13)×20 = 140μA 3.56 (a) 根据表3-7和表3-10， 74HCT的VOHminT = 3.84V，74LS的VIHmin = 2.0V ∴ High-state Noise Margin : 3.84 – 2.0 = 1.84V 74HCT的VOLmaxT = 0.33V，74LS的VILmax = 0.8V ∴ Low-state Noise Margin : 0.8 – 0.33 = 0.47V (b) 根据表3-6和表3-10， 74ALS的VOHmin = 2.7V，74HCT的VIHmin = 2.0V ∴ High-state Noise Margin : 2.7 – 2.0 = 0.7V 74ALS的VOLmax = 0.5V，74HCT的VILmax = 0.8V ∴ Low-state Noise Margin : 0.8 – 0.5 = 0.3V 本文来源：https://www.wddqw.com/doc/d4aa457eccbff121dd368362.html