![ESPE-DEEE ELÉCTRONICA I 3
Parameters of the zener diode
Voltage Zener Nominal (VZ):
As the name implies, this is the voltage at which the zener
diode is turned on in reverse polarization and under normal
temperature conditions. The zener come for voltages between
1.8V and 200V. This parameter is used as a reference to buy the
zener diode.
Tolerance:
Similar to the one used for resistors, it indicates the range of
error that can be expected in the nominal zener voltage,
tolerances of 20%, 10%, 5% and 1% are common (eg a zener
of 10V / 20% can have a zener voltage between 8V and 12V).
Obviously at lower tolerance higher cost.
Minimum Zener Intensity:
Unlike the common diode, the zener apart from needing a
voltage greater than the breaking to operate, needs a minimum
current of ignition. Due to the difficulty in obtaining this value
it is always considered to have a value of 5mA.
Maximum Zener Intensity (IZ MAX):
It is the maximum intensity that the zener supports in reverse
polarization. This parameter is very important since there will
be times when the load is disconnected, so the charge current
will pass to the zener and if it is too high, the zener will burn.
Maximum Dissipated Power (PZ):
This parameter is more commonly used than the maximu m
zener intensity and specifies the maximum power that can
dissipate the zener packing in the form of heat.The zener come
in powers between 0.25W to 50W. This is the second parameter
that is used as reference to buy the zener diode. If the calculated
power is very high you can use zener diodes in parallel in order
to divide the total current, getting less power dissipation per
zener.
B. SAMPLE DESING
CIRCUIT I
Figure 5 Circuit one
To find each of the voltages and currents of a variable load
resistor, a circuit analysis must be performed.
When having an input voltage of 12 V the Zenner diode lead.
To obtain the resistance current of 33 Ω you have to:
𝐼 𝑅 = 𝐼 𝐿 + 𝐼 𝑍
𝐼 𝑅 =
𝑉𝐴 − 𝑉𝐵
𝑅
=
12 − 5.6
33
= 𝟎. 𝟏𝟗𝟒[𝐀]
To know the minimum load resistance, the following formula
is used:
𝑅 𝐿𝑚𝑖𝑛 =
𝑉𝑍
𝐼 𝐿𝑀𝐴𝑋
Taking as data the voltage and the max current of the Zenner
diode that are 5.6 V and 100mA respectively, it can be
concluded that:
𝐼 𝑍𝑚𝑖𝑛 = 10 𝑚𝐴
Therefore, to obtain the 𝐼 𝐿𝑚𝑖𝑛, it is cleared from the first
equation obtaining:
𝐼 𝐿𝑚𝑖𝑛 = 𝐼 𝑅 − 𝐼 𝑍𝑀𝐴𝑋
𝐼 𝐿𝑚𝑖𝑛 = 0.194 − 0.100 = 𝟗𝟒[𝒎𝑨]
Thus:
𝑅 𝐿𝑚𝐴𝑋 =
𝑉𝑍
𝐼 𝐿𝑚𝑖𝑛
𝑅 𝐿𝑚𝐴𝑋 =
5.6
94
= 𝟓𝟗. 𝟓𝟕Ω
And for 𝑅 𝐿𝑚𝑖𝑛 you have to:
𝐼 𝐿𝑀𝐴𝑋 = 𝐼 𝑅 − 𝐼 𝑍𝑚𝑖𝑛
𝐼 𝐿𝑚𝑖𝑛 = 0.194 − 0.010 = 𝟏𝟖𝟒[𝒎𝑨]
Thus:
𝑅 𝐿𝑚𝑖𝑛 =
𝑉𝑍
𝐼 𝐿𝑀𝐴𝑋
𝑅 𝐿𝑚𝑖𝑛 =
5.6
184
= 𝟑𝟎. 𝟒𝟑Ω
C. CIRCUIT II
Figure 6 Circuit two
For the second circuit developed in practice we have a variable
source with a resistance of 220 Ω to 5 W a diode of 5.6 V and
172.8 mA as max current, finally a load resistance of 1.2 k Ω:
It has to:](https://image.slidesharecdn.com/informe4-171214041727/85/Informe-4-3-320.jpg)
![ESPE-DEEE ELÉCTRONICA I 4
𝐼 𝑅 = 𝐼 𝐿 + 𝐼 𝑍
𝐼 𝐿 =
𝑉𝑍
𝑅
=
5.6
1200
= 𝟒. 𝟔𝟕 [𝐦𝐀]
To know the current of the minimum 220 Ω resistance the
following formula is used:
𝐼 𝑅𝑚𝑖𝑛 = 𝐼 𝑍𝑚𝑖𝑛 + 𝐼 𝐿
𝐼 𝑅𝑚𝑖𝑛 = 0.01 + 0.00467 = 𝟏𝟒. 𝟔𝟕[𝒎𝑨]
Thus:
𝑉𝑖𝑛𝑚𝑖𝑛 = 𝑅 ∗ 𝐼 𝑅𝑚𝑖𝑛 + 𝑉𝑍
𝑉𝑖𝑛𝑚𝑖𝑛 = 220(0.01467) + 5.6 = 𝟖. 𝟖𝟑 [𝑽]
To find the maximum input voltage you must find the max
current of the 220 Ω resistor:
𝐼 𝑅𝑀𝐴𝑋 = 𝐼 𝐿 + 𝐼 𝑍𝑀𝐴𝑋
𝐼 𝑅𝑀𝐴𝑋 = 0.00467 + 0.1728 = 𝟏𝟕𝟕. 𝟒𝟕[𝒎𝑨]
Thus:
𝑉𝑖𝑛𝑀 𝐴𝑋 = 𝑅 ∗ 𝐼 𝑅𝑀𝐴𝑋 + 𝑉𝑍
𝑉𝑖𝑛𝑀𝐴𝑋 = 220(0.17747) + 5.6 = 𝟒𝟒. 𝟔𝟒 [𝑽]
D. Measurements
Table 1 Data obtained in laboratory
𝑅 𝐿 𝑉𝐿 𝐼 𝑍
31 Ω 5,7[v] 61,1[mA]
47 Ω 6,17[v] 108,3[mA]
62 Ω 6,32[v] 136[mA]
100 Ω 6,48[v] 167,1[mA]
147 Ω 6,55[v] 186,5[mA]
200 Ω 6,6[v] 195,1[mA]
Figure 7 Graphic of I-V of circuit one
Table 2 Data obtained in laboratory
𝑉𝑖𝑛 𝑉𝐿 𝐼 𝑍
3,12[V] 2,63[V] 0[mA]
6,1[V] 5,11[V] 0,14[mA]
8,85[V] 5,64[V] 9,52[mA]
10,2[V] 5,65[V] 15,53[mA]
14,8[V] 5,79[V] 35,63[mA]
6,9[V] 5,84[V] 44,7[mA]
20,1[V] 5,92[V] 58,5[mA]
23,7[V] 6[V] 74,4[mA]
0
50
100
150
200
250
5.6 5.8 6 6.2 6.4 6.6 6.8
I-V Circuitone
0
20
40
60
80
0 2 4 6 8
I-V Circuittwo
Figure 8 Graphic of I-V of circuit two](https://image.slidesharecdn.com/informe4-171214041727/85/Informe-4-4-320.jpg)
Informe 4
- 1. ESPE-DEEE ELÉCTRONICA I 1 Abstract— This document is made for the description and justification of the practice in the electronic laboratories of the University of the Armed Forces "ESPE" by the authors of the same, in which different measurements were made and the calculations of their respective errors are described. one of the semiconductor devices that play a vital role in electronicsystems, with features that closely resemble those of a switch that will be found in a wide range of applications, ranging from the simple to the more complex, worked with a Zener diode, first, the voltage was varied in a circuit, to find the breakdown voltage or Zener operation, these values were found experimentally, latera second circuit was configured in which the load resistance was varied to obtain a second characteristic curve of this diode. Index Terms— Diode Zener I. INTRODUCIÓN his document describes a diode that is an electronic component of two terminals that allows thecirculation of theelectric current through it in a single direction. Simplified, the characteristic curve of a diode (IV) consists of two regions: below a certain potential difference, it behaves as an open circuit (does not conduct) and higher as a closed circuit with a very small electrical resistance. Due to this behavior, they are generally called rectifiers, since they are devices capable of suppressingthenegative part of any signal, as an initial step to convert an alternating current into direct current, in our practice we have the Zener diode which is a device, designed to work In areas of rupture, this, unlike a common diode, is used inversely polarized (cathode-anode), although if it is directly polarized (anode-cathode), it works like a common diode. The advantage of the Zener is that when used in reverse bias, it functions as a voltage rectifier. II. METHODS AND MATERIALS A. THEORETICAL FRAMEWORK Zener diode A Zener diode is different; It is a silicon diode that has been designed to work in the rupture zone. Taking advantage of this effect, which consists of maintaining a constant voltage between its terminals regardless of the magnitude of the circulating current, Clarence Zener invented the Zener diode. The zener diode is a special type of diode that inversely polarized allows the current to flow against the arrow that represents it schematically while maintaining a constant voltage between its terminals; if it is directly polarized, it will behave like a common rectifier diode. Sometimes called an avalanche diode, the Zener diode is the essential part of the voltage regulators; These are circuits that keep the voltage almost constant,regardless of whether there are large variations in the network voltage and load resistance. Figure 1 Schematic symbol of the Zener diode Characteristics In direct polarization behaves like a common diode. When thediode is polarized inversely, a small current flows through it, called saturation current Is, this current remains relatively constant while increasing theinverse voltage until thevalue of it reaches Vz, called Zener voltage (which is not the voltage of zener break), for which the diode enters the collapse region. The current begins to increase rapidly due to the avalanche effect. After the break, the current increases keeping the voltage approximately constant at the value VBR = Vz. It is used as voltage regulator. The voltage is relatively insensitive to variations in the power or load current. Figure 2 Current-voltage curve Practice Report Nº 4 Zener diode (November 2017) First author Marjorie Mullo, Second author Diana Sandoval, and Third author David Tobar T
- 2. ESPE-DEEE ELÉCTRONICA I 2 Zener effect When the diode is reverse polarized, a small current flows through it, called saturation current Is, this current remains relatively constant while increasing the inverse voltage until the value of this reaches Vz, called Zener voltage (which is not the breaking voltage zener), for which the diode enters the collapse region. The current begins to increase rapidly due to the avalanche effect. In this region, small voltage changes produce large current changes.The zener diode keeps the voltage practically constant between its ends for a wide range of inverse current. Obviously, there is a drastic change in the effective resistance of the PN junction. Figure 3 Current-voltage characteristic of the Zener diode If the reverse voltage is decreased,the saturation current Is will be restored, when the reverse voltage is less than the zener voltage. The diode can change from one zone to the other in both directions without the diode being damaged, this is what differentiates it from a junction diode like the one we studied in the previous practice and is what gives the zener diode its special feature The progressive increase of the reverse polarization increases the current level and should not exceed a certain voltage level specified by the manufacturer, otherwise the diode would be damaged, and we should always take into account the maximum power that the diode can dissipate. Always work in the security region. Functioning Zener reverse polarized With small voltage values, the inverse saturation current is practically stable and negligible for practical purposes.If the elbow or rotation voltage continues to increase, where the current increases are considerable compared to the voltage increases. When this area is exceeded at small voltage increments, high increases in the Iz current correspond.Reached the previous circumstance, we will find ourselves in the region of effective work of the zener. We must make certain considerations at this time. It must be ensured that in working mode, the diode is crossed by at least one reverse current Iz expressed by the manufacturer to exclude the turning region from normal operation. Iz max must not be exceeded in any case to ensure the survival of the component. These two values of Iz are associated with a pair of voltage values, Vz; approximately the average value of themrepresents the nominal voltage of the zener Vz nom It is usually expressed in the characteristics a tolerance percentage on the nominal voltage. The power dissipated in each moment, Pz will be expressed by the product of the instantaneous values of Vz and Iz The values of Iz min and Iz max with their associated Vz values represent the region of work At this time we are able to ensure that in the region of work, the zener is able to maintain a considerably stable voltage at its ends. Figure 4 Voltage-current characteristic of the Zener diode The zener as voltage regulator: In many circumstances the voltage applied to a load may suffer undesirable variations that alter the normal operation of the load. These variations are usually caused by: A variation of the load resistance, which carries a variation of the load intensity. Variations of the power supply itself. If we choose a zener diode of nominal voltage equal to the one that is necessary to apply to the load and we are able to make it work in its working region, we will get a voltage with hardly any variations.
- 3. ESPE-DEEE ELÉCTRONICA I 3 Parameters of the zener diode Voltage Zener Nominal (VZ): As the name implies, this is the voltage at which the zener diode is turned on in reverse polarization and under normal temperature conditions. The zener come for voltages between 1.8V and 200V. This parameter is used as a reference to buy the zener diode. Tolerance: Similar to the one used for resistors, it indicates the range of error that can be expected in the nominal zener voltage, tolerances of 20%, 10%, 5% and 1% are common (eg a zener of 10V / 20% can have a zener voltage between 8V and 12V). Obviously at lower tolerance higher cost. Minimum Zener Intensity: Unlike the common diode, the zener apart from needing a voltage greater than the breaking to operate, needs a minimum current of ignition. Due to the difficulty in obtaining this value it is always considered to have a value of 5mA. Maximum Zener Intensity (IZ MAX): It is the maximum intensity that the zener supports in reverse polarization. This parameter is very important since there will be times when the load is disconnected, so the charge current will pass to the zener and if it is too high, the zener will burn. Maximum Dissipated Power (PZ): This parameter is more commonly used than the maximu m zener intensity and specifies the maximum power that can dissipate the zener packing in the form of heat.The zener come in powers between 0.25W to 50W. This is the second parameter that is used as reference to buy the zener diode. If the calculated power is very high you can use zener diodes in parallel in order to divide the total current, getting less power dissipation per zener. B. SAMPLE DESING CIRCUIT I Figure 5 Circuit one To find each of the voltages and currents of a variable load resistor, a circuit analysis must be performed. When having an input voltage of 12 V the Zenner diode lead. To obtain the resistance current of 33 Ω you have to: 𝐼 𝑅 = 𝐼 𝐿 + 𝐼 𝑍 𝐼 𝑅 = 𝑉𝐴 − 𝑉𝐵 𝑅 = 12 − 5.6 33 = 𝟎. 𝟏𝟗𝟒[𝐀] To know the minimum load resistance, the following formula is used: 𝑅 𝐿𝑚𝑖𝑛 = 𝑉𝑍 𝐼 𝐿𝑀𝐴𝑋 Taking as data the voltage and the max current of the Zenner diode that are 5.6 V and 100mA respectively, it can be concluded that: 𝐼 𝑍𝑚𝑖𝑛 = 10 𝑚𝐴 Therefore, to obtain the 𝐼 𝐿𝑚𝑖𝑛, it is cleared from the first equation obtaining: 𝐼 𝐿𝑚𝑖𝑛 = 𝐼 𝑅 − 𝐼 𝑍𝑀𝐴𝑋 𝐼 𝐿𝑚𝑖𝑛 = 0.194 − 0.100 = 𝟗𝟒[𝒎𝑨] Thus: 𝑅 𝐿𝑚𝐴𝑋 = 𝑉𝑍 𝐼 𝐿𝑚𝑖𝑛 𝑅 𝐿𝑚𝐴𝑋 = 5.6 94 = 𝟓𝟗. 𝟓𝟕Ω And for 𝑅 𝐿𝑚𝑖𝑛 you have to: 𝐼 𝐿𝑀𝐴𝑋 = 𝐼 𝑅 − 𝐼 𝑍𝑚𝑖𝑛 𝐼 𝐿𝑚𝑖𝑛 = 0.194 − 0.010 = 𝟏𝟖𝟒[𝒎𝑨] Thus: 𝑅 𝐿𝑚𝑖𝑛 = 𝑉𝑍 𝐼 𝐿𝑀𝐴𝑋 𝑅 𝐿𝑚𝑖𝑛 = 5.6 184 = 𝟑𝟎. 𝟒𝟑Ω C. CIRCUIT II Figure 6 Circuit two For the second circuit developed in practice we have a variable source with a resistance of 220 Ω to 5 W a diode of 5.6 V and 172.8 mA as max current, finally a load resistance of 1.2 k Ω: It has to:
- 4. ESPE-DEEE ELÉCTRONICA I 4 𝐼 𝑅 = 𝐼 𝐿 + 𝐼 𝑍 𝐼 𝐿 = 𝑉𝑍 𝑅 = 5.6 1200 = 𝟒. 𝟔𝟕 [𝐦𝐀] To know the current of the minimum 220 Ω resistance the following formula is used: 𝐼 𝑅𝑚𝑖𝑛 = 𝐼 𝑍𝑚𝑖𝑛 + 𝐼 𝐿 𝐼 𝑅𝑚𝑖𝑛 = 0.01 + 0.00467 = 𝟏𝟒. 𝟔𝟕[𝒎𝑨] Thus: 𝑉𝑖𝑛𝑚𝑖𝑛 = 𝑅 ∗ 𝐼 𝑅𝑚𝑖𝑛 + 𝑉𝑍 𝑉𝑖𝑛𝑚𝑖𝑛 = 220(0.01467) + 5.6 = 𝟖. 𝟖𝟑 [𝑽] To find the maximum input voltage you must find the max current of the 220 Ω resistor: 𝐼 𝑅𝑀𝐴𝑋 = 𝐼 𝐿 + 𝐼 𝑍𝑀𝐴𝑋 𝐼 𝑅𝑀𝐴𝑋 = 0.00467 + 0.1728 = 𝟏𝟕𝟕. 𝟒𝟕[𝒎𝑨] Thus: 𝑉𝑖𝑛𝑀 𝐴𝑋 = 𝑅 ∗ 𝐼 𝑅𝑀𝐴𝑋 + 𝑉𝑍 𝑉𝑖𝑛𝑀𝐴𝑋 = 220(0.17747) + 5.6 = 𝟒𝟒. 𝟔𝟒 [𝑽] D. Measurements Table 1 Data obtained in laboratory 𝑅 𝐿 𝑉𝐿 𝐼 𝑍 31 Ω 5,7[v] 61,1[mA] 47 Ω 6,17[v] 108,3[mA] 62 Ω 6,32[v] 136[mA] 100 Ω 6,48[v] 167,1[mA] 147 Ω 6,55[v] 186,5[mA] 200 Ω 6,6[v] 195,1[mA] Figure 7 Graphic of I-V of circuit one Table 2 Data obtained in laboratory 𝑉𝑖𝑛 𝑉𝐿 𝐼 𝑍 3,12[V] 2,63[V] 0[mA] 6,1[V] 5,11[V] 0,14[mA] 8,85[V] 5,64[V] 9,52[mA] 10,2[V] 5,65[V] 15,53[mA] 14,8[V] 5,79[V] 35,63[mA] 6,9[V] 5,84[V] 44,7[mA] 20,1[V] 5,92[V] 58,5[mA] 23,7[V] 6[V] 74,4[mA] 0 50 100 150 200 250 5.6 5.8 6 6.2 6.4 6.6 6.8 I-V Circuitone 0 20 40 60 80 0 2 4 6 8 I-V Circuittwo Figure 8 Graphic of I-V of circuit two