# Chapter 8: Voltage Regulation¶

## Example 8.1, Page 263¶

In [2]:
#Variable declaration
R1=5000;           #In Ohm
R2=20000.;           #In Ohm
R3=10000;           #In Ohm
Vz=3.9;         #In V

#Calculations&Results
Vl=Vz*(R2+R3)/R3;
print "Output Load Voltage Vl is = %.2f V\n"%Vl;
Iz=(Vl-Vz)/R1*10**3;
print "Output Zener Current Iz is = %.2f mA \n"%Iz

Output Load Voltage Vl is = 11.70 V

Output Zener Current Iz is = 1.56 mA



## Example 8.2, Page 264¶

In [3]:
#Variable declaration
Vl=11.7;            #in V
Rl=20;           #in Ohm

#Calculations&Results
Il=Vl/Rl;
print "Output Load Current Il is = %.3f A \n"%Il;
Vc=20; Ve=11.7;     #in V
Vce=Vc-Ve;
print "Output Load Voltage Vce is = %.2f V\n"%Vce;
Pd=Il*Vce;
print "Power dissiption Pd is = %.2f W \n"%Pd;
Ib=0.020;                   #in Amp
B=Il/Ib;
print "Beta is = %.2f  \n"%B;
Pl=Il*Vl;
print "Power dissiption across load ,Pl is = %.3f W \n"%Pl;
Vin=20;             #in V
Pin=Il*Vin;         #Iin=Il
print "Input Power dissiption ,Pin is = %.2f W \n"%Pin;
n=Pl/Pin;
print "Efficiency   is = %.3f or %.1f  percent \n"%(n,n*100);

Output Load Current Il is = 0.585 A

Output Load Voltage Vce is = 8.30 V

Power dissiption Pd is = 4.86 W

Beta is = 29.25

Power dissiption across load ,Pl is = 6.844 W

Input Power dissiption ,Pin is = 11.70 W

Efficiency   is = 0.585 or 58.5  percent



## Example 8.3, Page 272¶

In [5]:
#Variable declaration
Vm=1.25;            #in V
Vout=15;            #in V
R1=240;           #in Ohm

#Calculations
R2=R1*((Vout/Vm)-1)*10**-3;

#Result
print "Value for R2 is = %.2f kOhm\n"%R2

Value for R2 is = 2.64 kOhm



## Example 8.4, Page 279¶

In [8]:
#Variable declaration
Vref=7.15;            #in V
Vout=12;            #in V
Ilimit=0.050;           #in Amp
R2=10000;           #in Ohm

#Calculations&Results
R1=Vout*R2/Vref-R2;
print "Value of R1 is = %.2f Ohm\n"%R1;
Vsense=0.65;            #in V
Rsc=Vsense/Ilimit;
print "Value of current sense resistor is = %.f Ohm\n"%Rsc; # Result
R3=R1*R2/(R1+R2);
print "Value of minimum drift resistor is = %.f Ohm\n"%R3;

Value of R1 is = 6783.22 Ohm

Value of current sense resistor is = 13 Ohm

Value of minimum drift resistor is = 4042 Ohm



## Example 8.5, Page 279¶

In [9]:
#Variable declaration
Vref=7.15;            #in V
Vout=5;            #in V

#Calculations&Results
#(R1b+R2)/R2=Vref/Vout;
print "For maximum case (R1b+R2)/R2 is = %.2f \n"%(Vref/Vout);
R2=1;              # In Ohm (Assumption)
R1b=Vref/Vout-1;
print "For R2=1 Ohm R1b:R2 is = %.2f:%.0f \n"%(R1b,R2);
Voutm=2;           # in V
print "For maximum case (R1a+R1b+R2)/R2 is = %.3f \n"%(Vref/Voutm);
R1a=Vref/Voutm-1-0.43;
print "For R2=1 Ohm R1b:R2 is = %.3f:%.0f \n"%(R1a,R2);
R1a=10000;          #in Ohm        (Assumption)
R2=R1a/2.145;
print "Value of R2 is = %.f Ohm\n"%R2;
#Similarly
R1b=R2*0.43;
print "Value of R1b is = %.f Ohm\n"%R1b;
#Ilimit=Vsense/rsc;
Vsense=0.65;            #in V
Ilimit=1;           #in Amp
Rsc=Vsense/Ilimit;
print "Value of current sense resistor is = %.f Ohm\n"%Rsc;
R1=6000;                #in Ohm
R3=R1*R2/(R1+R2);
print "Value of minimum drift resistor is = %.f Ohm\n"%R3;
Ic=1;               #in Amp
Ib=0.150;           #in Amp
B=Ic/Ib;
print "Value of B minimum  = %.2f \n"%B;

For maximum case (R1b+R2)/R2 is = 1.43

For R2=1 Ohm R1b:R2 is = 0.43:1

For maximum case (R1a+R1b+R2)/R2 is = 3.575

For R2=1 Ohm R1b:R2 is = 2.145:1

Value of R2 is = 4662 Ohm

Value of R1b is = 2005 Ohm

Value of current sense resistor is = 1 Ohm

Value of minimum drift resistor is = 2624 Ohm

Value of B minimum  = 6.67



## Example 8.6, Page 288¶

In [13]:
#Variable declaration
Vout=12;            #in V
R2=10000;          #in Ohm        (Assumption)

#Calculations&Results
R1=R2*(Vout-1)*10**-3;
print "Value of R1 is = %.f kOhm\n"%R1;
Isw=0.75;               #in Amp
R3=0.11/Isw;
print "Value of R3 is = %.2f Ohm\n"%R3;
Iout=0.200;         #in Amp
Df=0.2;
delI =2*Iout*Df;
print "Value of del I is = %.3f Amp\n"%delI;
F=50000;           #in Hz
Vin=20;         #in V
L1=Vout*(Vin-Vout)/(delI*Vin*F);
print "Value of L1 is = %.4f H\n"%L1;
Vripple=0.040;      #in V
C2=Vout*(Vin-Vout)/(8*F**2*Vin*Vripple*L1)*10**6;
print "Value of C2 is = %.f uF\n"%C2;
#C2 is ste a standard of 33microF or 47microF

Value of R1 is = 110 kOhm

Value of R3 is = 0.15 Ohm

Value of del I is = 0.080 Amp

Value of L1 is = 0.0012 H

Value of C2 is = 5 uF



## Example 8.7, Page 296¶

In [15]:
#Variable declaration
Tj=150.;           # in degree C
Ta=40;           # in degree C
Qjc=3.0;          # in  C/W
Qcs=1.6;          # in  C/W
PD=6;           #in W

#Calculations
Qsa=(Tj-Ta)/PD - Qjc-Qcs;

#Result
print "Value of Qsa = %.2f C/W\n"%Qsa;

Value of Qsa = 13.73 C/W