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{
"cells": [
{
"cell_type": "heading",
"level": 1,
"metadata": {},
"source": [
"Chapter 9: Semiconductor Theory and Devices"
]
},
{
"cell_type": "heading",
"level": 2,
"metadata": {},
"source": [
"Example 9.1, Page 277"
]
},
{
"cell_type": "code",
"collapsed": false,
"input": [
"\n",
"# Part (a)\n",
"V_Z = 9.1; # Zener voltage of zener diode, volt\n",
"P_Z = 0.5; # Power rating of zener diode at V_Z, W\n",
"r_Z = 1.5; # Slope resistance of zener diode, ohm\n",
"V = 12; # Nominal value of input voltage, volt\n",
"R_L = 2.5e+03; # Load resistance across zener diode, ohm\n",
"\n",
"\n",
"I_Z = P_Z/V_Z*1e+03; # Zener current, mA\n",
"I_S = I_Z; # Current through series resistor, mA\n",
"V_S = V - V_Z; # Voltage drop across series resistor, volt\n",
"R_S = V_S/I_S*1e+03; # Value of series resistance, ohm\n",
"P_max = (I_S*1e-03)**2*R_S; # Maximum power rating of series resistance, W\n",
"print \"The value of series resistance = %5.2f ohm\"%R_S\n",
"print \"The value of maximum power rating of series resistance = %4.2f W\"%P_max\n",
"print \"(a) The suitable value of R_S should be 54 ohm, 0.25 W\"\n",
"\n",
"# Part (b)\n",
"V_o = V_Z; # Output voltage across zener, volt\n",
"I_L = V_o/R_L*1e+03; # Load current, mA\n",
"I_Z = I_S - I_L; # Zener current, mA\n",
"print \"(b) The value of diode current with load resistance across zener = %5.2f mA\"%I_Z \n",
"\n",
"# Part (c)\n",
"V = 12 - (0.1*12); # Final value of input voltage after falling below 12 V, volt\n",
"R_S = 56; # Standard value of series resistance, ohm\n",
"I_S = (V - V_Z)/R_S*1e+03; # Current through series resistance, mA\n",
"I_Z = I_S - I_L; # Resulting diode current, mA\n",
"delta_I_Z = 51.36 - I_Z; # Change in zener current, mA\n",
"delta_V_Z = delta_I_Z*1e-03*r_Z; # Change in zener voltage, V\n",
"change = delta_V_Z/V_Z*100; # %age change in zener voltage\n",
"print \"(c) The percentage change in the p.d. across the load = %4.2f percent\"%change\n"
],
"language": "python",
"metadata": {},
"outputs": [
{
"output_type": "stream",
"stream": "stdout",
"text": [
"The value of series resistance = 52.78 ohm\n",
"The value of maximum power rating of series resistance = 0.16 W\n",
"(a) The suitable value of R_S should be 54 ohm, 0.25 W\n",
"(b) The value of diode current with load resistance across zener = 51.31 mA\n",
"(c) The percentage change in the p.d. across the load = 0.41 percent\n"
]
}
],
"prompt_number": 1
},
{
"cell_type": "heading",
"level": 2,
"metadata": {},
"source": [
"Example 9.2, Page 279"
]
},
{
"cell_type": "code",
"collapsed": false,
"input": [
"import numpy as np\n",
"\n",
"#Variable declaration\n",
"Diode = np.array([3, 1]); # Declare a diode cell\n",
"Diode_1 = [1, 15, 30, 0.5, 0.007]; # Data for Ist diode\n",
"Diode_2 = [2, 15, 15, 1.3, 0.20]; # Data for 2nd diode\n",
"Diode_3 = [1, 15, 2.5, 5.0, 0.67]; # Data for 3rd diode\n",
"Resistor = np.array([5, 1]) # Declare a resistor cell\n",
"Resistor_1 = [0.25, 0.026]; # Data for Ist resistor\n",
"Resistor_2 = [0.5, 0.038]; # Data for 2nd resistor\n",
"Resistor_3 = [1.0, 0.055]; # Data for 3rd resistor\n",
"Resistor_4 = [2.5, 0.260]; # Data for 4th resistor\n",
"Resistor_5 = [7.5, 0.280]; # Data for 5th resistor\n",
"V = 24; # Input voltage, volt\n",
"\n",
"#Calculations&Results\n",
"V_Z = Diode_1[1]; # Zener voltage for Ist diode, volt\n",
"V_S = V - V_Z; # Voltage drop across series resistor for all the three diodes, volt\n",
"\n",
"#Part (a)\n",
"# Diode 1\n",
"P_Z = Diode_1[3]; # Power rating of Ist diode, W\n",
"I_Z = P_Z/V_Z*1e+03; # Zener current, mA\n",
"R_S = V_S/I_Z*1e+03; # Value of series resistance, ohm\n",
"P_S = V_S**2/R_S; # Power dissipation across series resistor, watt\n",
"print \"Diode 1:\";\n",
"print \"========\";\n",
"print \"The value of series resistance = %3d ohm\"%R_S;\n",
"print \"The value of power rating of series resistance = %3.1f W\"%P_S\n",
"R_S = 270; # Chosen value of series resistor, ohm\n",
"P_S = 0.3; # Chosen value of power rating, ohm\n",
"print \"The suitable value of R_S should be %3d ohm, %3.1f W\"%(R_S, P_S);\n",
"print \"Total unit cost = %5.3f pounds\\n\"%(Diode_1[4]+Resistor_2[1]);\n",
"\n",
"# Diode 2\n",
"print \"Diode 2:\";\n",
"print \"========\";\n",
"P_Z = Diode_2[3]; # Power rating of 2nd diode, W\n",
"I_Z = P_Z/V_Z*1e+03; # Zener current, mA\n",
"R_S = V_S/I_Z*1e+03; # Value of series resistance, ohm\n",
"P_S = V_S**2/R_S; # Power dissipation across series resistor, watt\n",
"print \"The value of series resistance = %5.2f ohm\"%R_S\n",
"print \"The value of power rating of series resistance = %4.2f W\"%P_S\n",
"R_S = 120; # Chosen value of series resistor, ohm\n",
"P_S = 1.0; # Chosen value of power rating, ohm\n",
"print \"The suitable value of R_S should be %3d ohm, %3.1f W\"%(R_S, P_S);\n",
"print \"Total unit cost = %4.2f pounds\"%(Diode_2[4]+Resistor_3[1]);\n",
"\n",
"# Diode 3\n",
"print \"\\nDiode 3:\";\n",
"print \"========\";\n",
"P_Z = Diode_3[3]; # Power rating of 3rd diode, W\n",
"I_Z = P_Z/V_Z*1e+03; # Zener current, mA\n",
"R_S = V_S/I_Z*1e+03; # Value of series resistance, ohm\n",
"P_S = V_S**2/R_S; # Power dissipation across series resistor, watt\n",
"print \"The value of series resistance = %3d ohm\"%R_S;\n",
"print \"The value of power rating of series resistance = %3.1f W\"%P_S\n",
"R_S = 27; # Chosen value of series resistor, ohm\n",
"P_S = 7.5; # Chosen value of power rating, ohm\n",
"print \"The suitable value of R_S should be %3d ohm, %3.1f W\"%(R_S, P_S);\n",
"print \"Total unit cost = %4.2f pounds\"%(Diode_3[4]+Resistor_5[1]);\n",
"\n",
"# Part (b)\n",
"delta_V_Z = (5*15)/100; # Allowable change in V_Z, volt\n",
"delta_I_Z = 30e-03; # Allowable change in zener current, A\n",
"delta_VZ = np.zeros(3);\n",
"delta_VZ_1 = 30e-03*30; # Change in zener voltage dor diode 1, V\n",
"delta_VZ_2 = 30e-03*15; # Change in zener voltage dor diode 2, V\n",
"delta_VZ_3 = 30e-03*2.5; # Change in zener voltage dor diode 3, V\n",
"print \"\\nThe maximum value of zener voltage change = %4.2f V\"%(max(delta_VZ_2, delta_VZ_3));\n",
"print \"To meet the specification at lowest cost, circuit 2 would be adopted\";\n",
"\n"
],
"language": "python",
"metadata": {},
"outputs": [
{
"output_type": "stream",
"stream": "stdout",
"text": [
"Diode 1:\n",
"========\n",
"The value of series resistance = 269 ohm\n",
"The value of power rating of series resistance = 0.3 W\n",
"The suitable value of R_S should be 270 ohm, 0.3 W\n",
"Total unit cost = 0.045 pounds\n",
"\n",
"Diode 2:\n",
"========\n",
"The value of series resistance = 103.85 ohm\n",
"The value of power rating of series resistance = 0.78 W\n",
"The suitable value of R_S should be 120 ohm, 1.0 W\n",
"Total unit cost = 0.26 pounds\n",
"\n",
"Diode 3:\n",
"========\n",
"The value of series resistance = 27 ohm\n",
"The value of power rating of series resistance = 3.0 W\n",
"The suitable value of R_S should be 27 ohm, 7.5 W\n",
"Total unit cost = 0.95 pounds\n",
"\n",
"The maximum value of zener voltage change = 0.45 V\n",
"To meet the specification at lowest cost, circuit 2 would be adopted\n"
]
}
],
"prompt_number": 2
}
],
"metadata": {}
}
]
}