AReS

PART5Semiconductor

Experiment 2 :Characteristic of Zener Diode

Theory

fig5-5

Fig. 5-5Characteristic Curve of Zener Diode

Zener diode is similar to other diodes except it uses reverse yield point. Therefore, the reverse yield point is controlled carefully during the production process and the zener voltage can be any value from 2~3V to over 200V. Fig. 5-5 (a) shows the characteristic curve of zener diode to certain current and voltage. I_ZK is the minimum reverse current when the diode operates within the breakdown region and I_ZM is the maximum reverse current which the diode can endure without exceeding rated power. The incline between I_ZK and I_ZM is known as zener impedance Z_Z. The incline can be calculated by dividing change amount of horizontal axis with that of vertical axis. The changes of voltage, current or other variables can be expressed as Greek character Δ(delta). Therefore, the incline in Fig. 5-5 can be expressed as ΔV/ΔI.

When operating zener diode between I_ZK and I_ZM, the voltage of diode’s both ends becomes comparably regular. This principle is used in the circuit of Fig. 5-5(b). 20~30V of unstabilized DC voltage is impressed to the circuit and reverse bias is applied to the zener diode, and it is assumed that if it is over I_ZK, enough reverse current is supplied so that the diode can be within the coordination area in Fig. 5-5(a). Then, even though the input voltage changes from 20V to 30V, the output voltage will be maintained relatively constant. Therefore, zener diode controls the output voltage and it is put in parallel to the output circuit so it is called a parallel regulator. Note that V_out=V_z In Fig. 5-5 (b), R_s should be chosen properly to maintain zener regulator and to make enough current flow so that needed load current can be supplied. If reverse zener current is operated at I_ZK, the load changes within certain range. If the load changes from 0 to 100mA and I_ZK is 100mA at zener diode, when the voltage of R_s both ends is minimum, the current flowing through R_s will be minimum. Therefore, R_s should be small enough to operate the circuit under all conditions and to supply I_ZK of zener diode and maximum load current of 100mA. Therefore, R_s is decided as below.

R_s=(V_(R_s ) min)/(I_in min+I_ZK )=(V_IN min-V_Z)/(I_L max+I_ZK )=(20V-15V)/(100mA+10mA)=5V/110mA=45.5Ω

When the minimum value of unstable input (V_{R_s} min) is 20V, and the maximum current of 100mA flows at the load, if R_s bigger than 45.5Ω is used, the zener cannot have enough reverse current. Therefore, considering safety factors, it is proper to set up R_s smaller than the calculated value.

Once proper value is set up to zener diode parallel regulator, it should be made safe so that R_s does not exceed the rated power of zener diode when the current bigger than minimum input voltage or maximum load current flows (The current of zener diode increases when the load current decreases). If the input voltage increases from the minimum value of 20V, the zener voltage is maintained relatively constant so the voltage of R_s both ends increases. Similarly, if the load changes so that the current smaller than 100mA flows, the decreases of load current appears through zener diode. Therefore, at the zener diode of parallel regulator, the maximum power dissipation occurs when the input voltage is maximum and the load current is minimum within the change range. Therefore, in the circuit of Fig. 5-4(b), the maximum zener current for R_s of 45.5Ω is calculated as below.

I_Z max= (V_(R_S ) max)/R_S -I_L min⁡

Here, I_L min : minimum load current
L_Z maz : maximum zener current
V_{R_s} max is from 30V to 15V, and I_L min is 0.

I_Z max= (30V-15V)/45.5Ω-0mA=330mA ⁡

Maximum power dissipated at the zener diode is same as the multiplication of zener voltage and zener current.

P_Z=V_Z∙I_Z ⁡

The maximum power dissipated at the zener diode occurs when I_Z is maximum. Therefore, P_Z=15V×330mA=4.95W.

Experiment Process

fig5-6

Fig. 5-6Zener Diode Characteristic

tab1

Experiment 5-2.1 6.1V Zener Diode Characteristic Measurement
(In Circuit-2 of M-05, compose a circuit as in Fig. 5-6(a), (b).)

When D1=Zener Diode 6.1V, R1= 1kΩ

1.Connection(Circuit-2 of M-05, Fig. 5-6(a))

1.Circuit Connection

Connect between 2c terminal and 2i terminal of Circuit-2 with yellow line, and between 2e terminal and 2k terminal with yellow line.

2.Power Connection

Connect between V1 terminal of Variable Power on M04 board and 2a(+) terminal of Sig Input & DC Input of Circuit-2 with red line, and between com terminal and 2b(-) terminal with black line.

3.Measuring Instrument Connection

Voltmeter Connection

Voltage Measurement between resistance R3, R4, R5, R6: Connect between 2k terminal of R3 and High terminal of Multimeter on the front panel with red line, and between 2q terminal and Low terminal with black line.

2.Wiring Diagram

flash

3.Measurement

1Choose dmm at the left menu of Touch LCD panel and choose dcv.
2Choose quick launch at the bottom of Touch LCD panel and click Variable Power then 3 CH DC screen appears.
3Click arrow rightat the right of 00.0V in DC Voltage V1 indication window to set up the input voltage as 6V and click on and record the voltage value of R3’s both ends indicated at DMM in the relevant column of table 5-3.

Voltage of R3’s Both Ends in Case of 6V Input

For the voltage of R4’s both ends, move the connection line of 2l to 2l and record the voltage value indicated at DMM in the relevant column of table 5-3.

For the voltage of R5’s both ends, move the connection line of 2m to 2m and record the voltage value indicated at DMM in the relevant column of table 5-3.

For the voltage of R6’s both ends, move the connection line of 2n to 2n and record the voltage value indicated at DMM in the relevant column of table 5-3.

Voltage of R6’s Both Ends in Case of 6V Input
4Click arrow right at the right of 06.0V inDC Voltage V1 indication window to set up the input voltage as 8V, 10V, 12V, 14V, 16V and execute Measurement 3) process and record the measured value in the relevant column of table 5-3.
5After the measurement, click on red to cut off the output.

When D1=Zener Diode 6.1V, R1= 220Ω

1.Connection(Circuit-2 of M-05, Fig. 5-6(b))

1.Circuit Connection

Connect between 2f terminal and 2i terminal of Circuit-2 with yellow line, and between 2h terminal and 2k terminal with yellow line.

2.Power connection is same as [When D1, R1= 1kΩ]>Connection>Power Connection.

3.Measuring instrument connection is same as [When D1, R1= 1kΩ]>Connection>Measuring Instrument Connection.

2.Wiring Diagram

flash

3.Measurement

1Execute same as [When D1, R1= 1kΩ]>Measurement and record in the relevant column of table 5-3.

Voltage of R3’s Both Ends in Case of 6V Input

Voltage of R6’s Both Ends in Case of 6V Input
2After the measurement, click on red to cut off the output.

4.Calculation

1. In the circuit of Fig. 5-6(a) (b), calculate the load current (IL) flowing on the load R3 and the zener current(IZ) flowing on the zener diode.

tab2

Experiment 5-2.2 Zener Diode Characteristic Measurement
(In Circuit-2 of M-05, compose a circuit as in Fig. 5-6(a), (b).)

When D2=Zener Diode 9.1V, R1= 1kΩ

1.Connection(Circuit-2 of M-05, Fig. 5-6(a))

1.Circuit Connection

Connect between 2c terminal and 2j terminal of Circuit-2 with yellow line, and between 2e terminal and 2k terminal with yellow line.

2.Power Connection

Connect between V3 terminal of Variable Power on M04 board and 2a(+) terminal of Sig Input & DC Input of Circuit-2 with red line, and between com terminal and 2b(-) terminal with black line.

3.Measuring Instrument Connection

Voltmeter Connection

Voltage Measurement between resistance R3: Connect between 2k terminal of R3 and High terminal of Multimeter on the front panel with red line, and between 2q terminal and Low terminal with black line.

2.Wiring Diagram

flash

3.Measurement

1Execute same as [When D1, R1= 1kΩ]>Measurement 1)~4) process and record in the relevant column of table 5-4

Voltage of R3’s Both Ends in Case of 16V Input

Voltage of R6’s Both Ends in Case of 16V Input
2After the measurement, click on red to cut off the output.

When D2=Zener Diode 9.1V, R1= 220Ω

1.Connection(Circuit-2 of M-05, Fig. 5-5(b))

1.Circuit Connection

Connect between 2f terminal and 2j terminal of Circuit-2 with yellow line, and between 2h terminal and 2k terminal with yellow line

2.Power connection is same as [When D1, R1= 1kΩ]>Connection>Power Connection.

3.Measuring instrument connection is same as [When D1, R1= 1kΩ]>Connection>Measuring Instrument Connection

2.Wiring Diagram

flash

3.Measurement

1Execute same as [When D1, R1= 1kΩ]>Measurement 1)~4) process and record in the relevant column of table 5-4

Voltage of R3’s Both Ends in Case of 16V Input

Voltage of R6’s Both Ends in Case of 16V Input
2After the measurement, click on red to cut off the output.

4.Calculation

1. In the circuit of Fig. 5-5(a) (b), calculate the load current (I_L) flowing on the load R3 and the zener current(I_Z) flowing on the zener diode.

Experiment Result Report

result
Title	Characteristic of Zener Diode	Date
Department		Id Number		Name

1. Experiment Result Table

Table 5-3 Zener Diode 6.1V Circuit

result_table
Input Load Input Voltage	R1 : 1㏀				R2 : 220Ω
Input Load Input Voltage	R3 1㏀	R4 470Ω	R5 220Ω	R6 100Ω	R3 1㏀	R4 470Ω	R5 220Ω	R6 100Ω
6V
8V
10V
12V
14V
16V

Table 5-4 Zener Diode 9.1V Circuit

result_table
Input Load Input Voltage	R1 : 1㏀				R2 : 220Ω
Input Load Input Voltage	R3 1㏀	R4 470Ω	R5 220Ω	R6 100Ω	R3 1㏀	R4 470Ω	R5 220Ω	R6 100Ω
6V
8V
10V
12V
14V
16V

2. Review and Explanation

1) In the circuit of Fig. 5-5(a) (b), calculate the load current (I_L) flowing on the load and the zener current(I_Z) flowing on the zener diode with the formula below and record it in the table.

- 1st step: Calculate series current. I_s=(V-V_Z)/R_S
- 2nd step: Judge load voltage. V_L=V_Z
- 3rd step: Calculate load current. I_L=V_L/R_Lc
- 4th step: Calculate zener current. I_Z=I_S-I_L

R_s: Series Resistance
V_L: Load Voltage
V_Z: Zener Voltage
I_Z: Zener Current
I_s: Series Resistance Current
I_L: Load Resistance Current

Table Zener Diode 6.1V Circuit

result_table
Input Voltage V	Vs	I_s	V_L=V_Z	I_L	I_Z
	When R1=Rs 1kΩ	I_S=V_S/R_S	When R3=RL 1kΩ	I_L=V_L/R_L	I_Z=I_S-I_L
	Vs=V-V_L	I_S=V_S/R_S	Measured Value	I_L=V_L/R_L	I_Z=I_S-I_L
6V
8V
10V
12V
14V
16V
Input Voltage V(V)	Vs(V)	I_s(mA)	V_L=V_Z	I_L(mA)	I_Z(mA)
	When R2=Rs 220Ω	I_S=V_S/R_S	When R3=RL 1kΩ	I_L=V_L/R_L	I_Z=I_S-I_L
	Vs=V-V_L	I_S=V_S/R_S	Measured Value	I_L=V_L/R_L	I_Z=I_S-I_L
6V
8V
10V
12V
14V
16V

Table Zener Diode 9.1V Circuit

result_table
Input Voltage V	Vs	I_s	V_L=V_Z	I_L	I_Z
	When R1=Rs 1kΩ	I_S=V_S/R_S	When R3=R_L 1kΩ	I_L=V_L/R_L	I_Z=I_S-I_L
	Vs=V-V_L	I_S=V_S/R_S	Measured Value	I_L=V_L/R_L	I_Z=I_S-I_L
6V
8V
10V
12V
14V
16V
Input Voltage V	Vs(V)	I_s(mA)	V_L=V_Z	I_L(mA)	I_Z(mA)
	When R2=Rs 220Ω	I_S=V_S/R_S	When R3=R_L 1kΩ	I_L=V_L/R_L	I_Z=I_S-I_L
	Vs=V-V_L	I_S=V_S/R_S	Measured Value	I_L=V_L/R_L	I_Z=I_S-I_L
6V
8V
10V
12V
14V
16V

2) After the experiment, draw the characteristic curve on Graph 5-1 and 5-2

Red Full Line : V_S to V_L Voltage Characteristic when R1=R_S 1kΩ, R3=R_L 1kΩ
Blue Full Line : V_S to V_L Voltage Characteristic when R1=R_S 220Ω, R3=R_L 1kΩ
Red Dotted Line : V_S to V_L Voltage Characteristic when R1=R_S 1kΩ, R3=R_L 1kΩ
Blue Dotted Line : V_S to V_L Voltage Characteristic when R1=R_S 220Ω, R3=R_L 1kΩ

section paper

Graph 5-1 (Zener Diode 6.1V Circuit, Characteristic Curve of V_S to V_L and V_S to I_L)

section paper

Graph 5-2 (Zener Diode 9.1V Circuit, Characteristic Curve of V_S to V_L and V_S to I_L)

PART5Semiconductor

Experiment 2 :Characteristic of Zener Diode

Theory

Experiment Process

Experiment 5-2.1 6.1V Zener Diode Characteristic Measurement (In Circuit-2 of M-05, compose a circuit as in Fig. 5-6(a), (b).)

1.Connection(Circuit-2 of M-05, Fig. 5-6(a))

1.Circuit Connection

2.Power Connection

3.Measuring Instrument Connection

2.Wiring Diagram

flash

3.Measurement

1.Connection(Circuit-2 of M-05, Fig. 5-6(b))

1.Circuit Connection

2.Power connection is same as [When D1, R1= 1kΩ]>Connection>Power Connection.

3.Measuring instrument connection is same as [When D1, R1= 1kΩ]>Connection>Measuring Instrument Connection.

2.Wiring Diagram

flash

3.Measurement

4.Calculation

Experiment 5-2.2 Zener Diode Characteristic Measurement (In Circuit-2 of M-05, compose a circuit as in Fig. 5-6(a), (b).)

1.Connection(Circuit-2 of M-05, Fig. 5-6(a))

1.Circuit Connection

2.Power Connection

3.Measuring Instrument Connection

2.Wiring Diagram

flash

3.Measurement

1.Connection(Circuit-2 of M-05, Fig. 5-5(b))

1.Circuit Connection

2.Power connection is same as [When D1, R1= 1kΩ]>Connection>Power Connection.

3.Measuring instrument connection is same as [When D1, R1= 1kΩ]>Connection>Measuring Instrument Connection

2.Wiring Diagram

flash

3.Measurement

4.Calculation

Experiment Result Report

1. Experiment Result Table

2. Review and Explanation

1) In the circuit of Fig. 5-5(a) (b), calculate the load current (IL) flowing on the load and the zener current(IZ) flowing on the zener diode with the formula below and record it in the table.

2) After the experiment, draw the characteristic curve on Graph 5-1 and 5-2

3) In the characteristic curve of Graph 5-1 and 5-2, interpret the characteristic of zener diode.

3. Discuss the experiment result.

Experiment 5-2.1 6.1V Zener Diode Characteristic Measurement
(In Circuit-2 of M-05, compose a circuit as in Fig. 5-6(a), (b).)

Experiment 5-2.2 Zener Diode Characteristic Measurement
(In Circuit-2 of M-05, compose a circuit as in Fig. 5-6(a), (b).)

1) In the circuit of Fig. 5-5(a) (b), calculate the load current (I_L) flowing on the load and the zener current(I_Z) flowing on the zener diode with the formula below and record it in the table.