1. Study of Voltage Regulator
LAB:- CEII (SEM V EXTC)

2. Aim and Apparatus
Aim : Design and study of voltage regulator Apparatus : IC 723, Resistors, Capacitors, Unregulated Power supply, Multimeter.
fig 1
LAB:- CEII (SEM V EXTC)

3. Theory
IC 723 has unregulated dc supply at input between 11.5 V to 40 V. It can withstand maximum load current of 150 mA. Internal power dissipation is about 800 mW. It has low temperature and high ripple rejection. The output voltage can be adjusted between 2 V to 37 V. The pin configuration of IC 723 is shown in fig 1.
Reference :
LAB:- CEII (SEM V EXTC)

4. The maximum ratings of IC 723 is shown in fig 3:
The functional block diagram of IC 723 consists of a reference generating block. The main function of this block is to generate a fixed reference voltage internally with the help of zener diode. The error amplifier is a high gain differential amplifier with two inputs. The non- inverting terminal is connected to the internally generated reference voltage. The inverting terminal is connected to full regulated output voltage. The series pass transistor is driven by the error amplifier. This transistor acts as a variable resistor and regulates the output voltage. The circuitry to limit the current is used to stop the flow of excess current passing through the circuit. The frequency compensation terminal is used to decide the frequency response of the error amplifier. The simplified internal structure of IC 723 is shown in fig 2:
The maximum ratings of IC 723 is shown in fig 3:
Reference :
fig 2
Sr No
Parameter
Maximum value 1
Pulsed Voltage
50 V 2
Continuous Voltage
40 V 3
Input Output Voltage Differential 4
Maximum Amplifier Input Voltage-Either Input
8.5 V 5
Maximum Amplifier Input Voltage-Differential
5 V 6
Internal Power Dissipation
660 mW 7
Output Current
150 mA
fig 3
LAB:- CEII (SEM V EXTC)

5. Design Problem
Question:-Design a voltage regulator IC 723 for following specifications: V0=5V ; I0=100mA; Vin= 15±20%; ISC= 150mA; Vsense=0.7V
Solution: Rsc= 𝑉𝑠𝑒𝑛𝑠𝑒 𝐼𝑠𝑐 =?
Neglecting input bias current
R1= 𝑉𝑟𝑒𝑓−𝑉𝑜 𝐼𝑜 =?
VO= Vf+ 𝑅2 𝑅1+𝑅2
R2=?
R3=R1//R2=?
LAB:- CEII (SEM V EXTC)

6. Input Unregulated Voltage (V) Regulated Output Voltage (V)
Procedure: )Design the given problem and connect the circuit. 2)Apply unregulated input voltage at pin )Check the output at pin 2 using the multimeter. 4)Note the output and vary the input voltage. 5)Repeat steps 2 to 4 till Vcc=25V.
Observation:
Result :
The regulator output is constant at 5.07 over range of inputs of 15-25V using IC723.
Input Unregulated Voltage (V)
Regulated Output Voltage (V)
LAB:- CEII (SEM V EXTC)

7. References Internet and Books by Sergio Franco and Ramakant Gaykwad
LAB:- CEII (SEM V EXTC)