Marking of zener diodes in a glass case imported. Zener diode. Operating principle. Marking
The Color and Code program has an extensive service and allows solving a complex of tasks of various nature in one application: finding the nominal or type of radio components by code or color marking, determining the electrical parameters of the radio components; perform radio engineering calculations; find the type and select the desired size of the radio components; select analogs of radio components; study the destination of the legs of the microcircuits.
Description of the program Color and Code
The program has the ability to determine the parameters of a large range of radio components such as varicaps, transistors, capacitors, diodes, zener diodes, resistors, inductances and chip components, both by code color and color marking.
Color marking resistors
Code and color marking of transistors
You can determine the type of transistor by two and four colored points. There is also a function of the definition of graphic symbols, horizontal and vertical designation, mixed and non-standard.
Marking of diodes, zener diodes, varicaps
Diodes, zener diodes, varicaps are determined by colored rings from 1 to 3 rings.
Zener diode is also called the reference diode. Zener diodes are designed to stabilize the output voltage when the input oscillates or when the load value changes (rice 1 ).
Fig. 1 - Functional diagram of the stabilitron
For example, if the load needs to get 5 V, and the voltage of the power source fluctuates within 9 V. Zener diodes are used to reduce and stabilize the voltage supplied from the power source to the required 5 V. Of course, it is possible to use voltage stabilizers, in this case, or. However, their use is not always justified, therefore, in some cases they use zener diodes.
Outwardly, they look like diodes and have the form shown inrice 2 .
Fig. 2 - Appearance of zener diodes
The designation of the zener diodes in the diagrams is given inrice 3 .
The principle of the Zener diode
Now let's see how the zener diode stabilizes the voltage.
The main characteristic of the Zener diode, however, as well as the diode, is the current-voltage characteristic (IVC). It shows the dependence of the magnitude of the current flowing through the Zener diode on the magnitude of the voltage applied to it (rice 4 ).
The IVC of the zener diode has two branches.
Fig. 4 - Zener voltage characteristic
The direct branch of the Zener diode practically does not differ from the direct branches of ordinary diodes and for the latter it will also be working.
The normal operation of the Zener diode is when it is under reverse voltage. Therefore, for him, the working branch will be a reverse branch. It is located almost parallel to the axis of the reverse currents. There are two points on this characteristic curve:1 and2 (rice 4 ), between them is the working area of the Zener diode.
At a certain value of reverse voltageU st electrical breakdown occursp — n Zener diode transition and through nago flows already significant current. However, when changing over a wide range of current fromImin beforeImax voltage drop on zener diodeU st practically does not change (rice 4 ). Thanks to this property voltage stabilization is carried out.
If the current flowing through the zener diode exceeds the valueImax then the semiconductor structure will overheat, thermal breakdown will occur and the zener diode will fail.
To power supplyType zener diode connects through current limiting resistorRogr , which serves to limit the current flowing through the Zener diode, and also together with it forms a voltage divider (rice 5 ).
Fig. 5 - Zener diode switching circuit
Note, unlike the diode, the zener diode is connected in the opposite direction, i.e. the “+” of the power supply is fed to the cathode, and the “-” to the anode.
Parallel to the pins of the Zener diode connects the loadR n , at the terminals of which it is required to maintain a stable voltage.
The process of voltage stabilization is as follows. Increasing the supply voltage increases the total current of the circuit.I and therefore the currentIst flowing through a zener diodeVd and also increases the voltage drop across the current-limiting resistorR ogre . In this case, the voltage at the Zener diode and, accordingly, at the load remains almost unchanged.
When the load resistance changes, the total current is redistributed.I between the Zener diode and the load, and the magnitude of the voltage on them practically does not change.
If the voltage on the load is greater than the stabilization voltage of the Zener diode, then several series-connected Zener diodes are used. For example, if you need to get 10 V of stable voltage, then in the absence of the required Zener diode, you can turn on two Zener diodes in series of 5 V (rice 6 ).
Fig. 6 - Series connection of zener diodes
Also, Zener diodes are successfully used in automation systems as sensors that react to voltage changes. For example, if the voltage exceeds a certain value, the zener diode will open and a current will flow through the relay coil. As a result, the relay will work and give a command to other devices or it will simply signal that a certain voltage level has been exceeded.
In addition to the stabilization of the constant voltage, with the help of zener diodes it is possible to stabilize the alternating voltage. For this useconsecutive counter the inclusion of two zener diodes (rice 7 ).
Fig. 7 - Zener diode switching circuit for alternating voltage
Only the output will not be an ideal sine wave, but with cut off tops, i.e. the voltage shape will be close to the trapezoidrice 8, 9 ).
Fig. 8 - Oscillogram of input voltage
Fig. 9 - Oscillogram of voltage at the zener
Apply several ways of marking zener diodes. Zener in glass case, with flexible outputs, are marked in the most understandable way. As a rule, numbers separated by the Latin letter “V” are put on the case. For example,4 V 7 indicates that the stabilization voltage is 4.7 V;9 V 1 - 9.1 V and so on (rice 10 ).
Fig. 10 - Marking of zener diodes in glass housings
Zener diodes in a plastic case are labeled in the form of numbers and letters. By themselves, these numbers do not say anything, however, with the help of datasheet they can be easily deciphered. For example, the designation 1N5349B means that the stabilization voltage is 12 V (rice eleven ). In addition to voltage, this marking takes into account other parameters of the Zener diode.
Fig. 10 - Zener diode marking in plastic cases
A black or gray ring deposited on the housing of the zener diode denotes its cathode (rice 12 ).
Fig. 12 -
Marking smd zener diodes
Color rings are used as marking smd zener diodes. Similar marking is also used for Soviet non-smd zener diodes. In imported Zener diodes, a color ring is applied on the cathode side (rice 13 ). For decoding color rings use datasheet or online decryptors.
Fig. 13 - SMD stabilitron in glass case
Still made smd zener diodes with three conclusions (rice 14 ). One of them is not involved. These findings can be determined using a multimeter.
Fig. 14 - SMD Zener diode with three pins
In the absence of a reference book, datasheet, or fuzzy marking, the nominal voltage of the zener diode can be determined empirically. First, using a multimeter, you need to find out the appropriate conclusions and connect a Zener diode through a current-limiting resistor (see fig. 5 ). Then apply voltage from an adjustable power source. Smoothly changing the supplied voltage, you need to monitor the voltage change at the Zener diode. If the voltage at the zener diode does not change when the voltage of the power source changes, then this will be its stabilization voltage.
The outputs of the Zener diode are determined in the same way as. The multimeter should be set to the dialing mode and touch the appropriate pins to the probes (rice 15, 16 ).
Fig. 15 - Forward voltage
Fig. 16 - Reverse voltage
Under the action of the flowing current through the Zener diode it heats up. Released heat is dissipated into the surrounding space. The more the Zener diode is able to dissipate heat without overheating, the higher its dissipation power and the more current can be passed through it. As a rule, the larger the dimensions of the zener diode, the greater its power dissipation (rice 17 ).
Fig. 17 - power dissipation zener diodes
The marking of the diodes is a brief graphical symbol of the element on which the body is applied. The element base is currently so diverse, the cuts differ quite substantially. It is difficult to identify a diode: zener diode, tunnel, Gunn. Released varieties resembling a discharge lamp. LEDs are lit, adding to the confusion.
Perhaps, the section is called somewhat trivial, it was necessary to distinguish the usual diodes from the outdated vacuum tubes, the most modern SMD modifications. Ordinary semiconductor diodes - the simplest grief amateur radio.The side of the cylindrical body with a disk base, the legs contain an easily visible inscription painted with paint.
Semiconductor resistors. Distinguish with the naked eye?
The hull color does not matter, the size indirectly indicates the power dissipation. Powerful diodes often have a thread for a radiator mount. The result of the calculation of the thermal regime shows the lack of its own capabilities of the case, the cooling system is complemented by a mounted element. Today, power consumption is falling, reducing the linear dimensions of the instrument cases. The above allowed the use of glass. New body material is cheaper, more durable, safer.
- The first place is taken by the letter or number, briefly describing the material of the element:
- G (1) - compounds of germanium.
- K (2) - silicon compounds.
- And (3) - gallium arsenide.
- And (4) is an indium compound.
- The second letter in our case is D. Rectifying diode, or pulsed.
- The third place was chosen by the figure characterizing the applicability of the diode:
- Low frequency, current below 0.3 A.
- Low-frequency, current 0.3 - 10 A.
- Not used.
- Pulsed, recovery time over 500 ns.
- Pulsed, recovery time 150 - 500 ns.
- The same, the recovery time is 30 - 150 ns.
- Same time recovery 5 - 30 ns.
- However, the recovery time is 1–5 ns.
- Pulsed, the lifetime of non-core carriers is below 1 ns.
- The development number is composed of two digits, it may be absent altogether. A par below 10 is padded to the left with a zero. For example, 07.
- The group number is denoted by a letter; it defines the differences of properties, parameters. The letter is often the key, it can indicate the operating voltage, direct current, and much more.
In addition to labeling, reference books provide graphs by which you can solve the problem of selecting the operating point of a radio element. Information on production technology, case material, mass may be indicated. Information helps the hardware designer, lovers of practical meaning is not.
Import notation systems differ from domestic ones, they are well standardized. Therefore, using special tables, it is sufficient to simply find suitable analogues.
Every amateur radio operator knows the difficulty of identifying diodes surrounded by a glass case. On one person. At times, the manufacturer bothers to put clear marks, colored rings.According to the notation, three signs are introduced:
- Marks of areas of the cathode, anode.
- Body color, replaced by a color dot.
According to the state of affairs, at first glance we distinguish the types of diodes:
- The D9 family is marked with one or two colored rings of the anode area.
- Diodes KD102 in the area of the anode are indicated by a colored dot. The case is transparent.
- KD103 have a color-supplementing case, excluding 2D103A, indicated by the white point of the anode area.
- Families KD226, 243 are marked with a ring of the cathode region. Other labels are not provided.
- Two colored rings in the cathode area can be seen in the KD247 family.
- Diodes KD410 indicated by a point in the anode.
There are other clearly distinguishable labels. A more detailed classification will find, having studied the edition Kashkarov AP By marking radio elements. Beginners are concerned with the issue of determining the location of the cathode and the anode.
- You see: one side of the cylinder is provided with a dark stripe - a cathode was found. Colored may be part of the marking discussed today.
- Knowing how to exploit a multimeter, the anode is easy to find. Electrode, where we attach the red probe to open the valve (hear the bell).
- The new diode is equipped with an anode tendril longer than the cathode.
- We look through a magnifying glass through the glass case of the LED: a metal anode resembles a spearhead, smaller than the cathode.
- Old diodes contained arrow markings. The tip is a cathode. Allows you to determine the direction of inclusion visually. Modern radio installers have to train ingenuity, visual acuity, accuracy of manipulation.
Foreign products received a different designation system. Choosing an analogue, use special correspondence tables. The rest of the import base differs little from the domestic one. Marking is carried out according to the standards of JEDEC (USA), the European system (PRO ELECTRON). Colorful color code decoding tables are widely represented by network sources.
In the SMD version, the diode package is sometimes so small that there is no marking at all. Characteristics of devices depend a little on dimensions. The latter strongly affect the power dissipation. The greater the current passes through the circuit, the diode must be larger in size, which dissipates the arising (Joule-Lenz law) heat. According to the written SMD diode marking can be:
- Lack of marking.
SMD elements in the total volume of electronics occupy about 80% of the volume. Surface mounting. The invented method of electrical connection is the most convenient automated assembly lines. The marking of the SMD diode may not coincide with the filling of the case. With a large volume of production, manufacturers begin to cheat, put inside not at all what is caused by the symbol. From a large number of standards that are not consistent with one another, there is confusion about the use of microcircuit pins (for diodes, microassemblies).
Marking may include 4 digits indicating the size of the enclosure. They do not directly correspond to the dimensions, ask for more details in the GOST R1-12-0.062, GOST R1-12-0.125. For lovers who cannot afford to get regulations, it is easier to use reference tables. We keep in mind a fact: SMD cases from company to company may differ in trifles. As each manufacturer podgadvaet element base for their own products. Samsung has one distance from the motherboard of the washing machine, LG another. Dimensions of SMD packages will require different conditions of heat removal,other requirements are met.
Therefore, acquiring, according to the digits of the directory element, make additional measurements, if it is important. For example, in the case of home appliances repair. Otherwise, the purchased diodes may not get up at their destination. SMD lovers are not contacted due to the seeming complexity of installation, but for wizards this is common, since microelectronics is impossible without such a successful technology.
When choosing a diode, it is worth keeping in mind a fact: many cases can be essentially the same, but labeled differently. Some designations are completely devoid of numbers. Convenient to use search engines. The given cross table of correspondence of standard sizes is taken from the site selixgroup.spb.ru.
SMD diodes are often available in the SOD123 package. If there is a strip of any color or embossing on one end, this is the cathode (the place where you need to apply negative polarity in order to open the pn-junction). If only on the case there are inscriptions, then this is the designation of the case. If lines over one - characterizing the shell larger.
Item type and manufacturer
It is clear that the type of body for the designer is a minor thing.Some heat will dissipate through the surface of the element. From this point of view, it is necessary to consider a diode. The rest is important characteristics:
- Operating and reverse voltage.
- The maximum allowable current through the p-n-junction.
- Power dissipation, etc.
These parameters for semiconductor diodes are indicated by reference books. Marking helps to find the right among the mountains of waste paper. In the case of an SMD element, the situation is much more complicated. There is no uniform notation. And at the same time it is easier - the parameters from one diode to another do not change too much. Differ by and large power dissipation, operating voltage. Each SMD element is marked with a sequence of 8 letters and numbers, and some of the familiarity may not be used at all. This is the case with veterans of the industry, the giants of the electronics industry:
- Motorola (2).
- Texas Instruments.
- Now converted and partially sold by Siemens (2).
- Maxim Integrated Product.
The mentioned manufacturers are sometimes marked with two letters MO, TI, SI, MX. In addition, a couple of letters addresses:
- AD - Analog Devices;
- HP - Hewlett-Packard;
- NS - National Semiconductors;
- PC, PS - Philips Components, Semiconductors, respectively;
- SE - Seiko Instruments.
Of course, the appearance of the case does not always allow to determine the manufacturer, then in the search engine you need to immediately type the alphanumeric sequence.Other examples are noted: the NXP diode assembly in the SOD123W package does not carry any information other than the indicated line above. The manufacturer considers the information provided sufficient. Because SOD in itself is decrypted as a small outline diode. Others will find on the official website of the company (nxp.com/documents/outline_drawing/SOD123W.pdf).
Print space is limited, and this simplification is explained. The manufacturer is trying to minimally impede the performance of marking. Often used laser or screen printing. This will allow you to fit 8 characters in an area of only 4 square millimeters (A. Kashkarov, "Labeling of radio elements"). In addition to those indicated for diodes, the following types of enclosures are used:
- Cylindrical glass MELF (Mini MELF).
- SMA, SMB, SMC.
To top it off, the same alphanumeric code sometimes corresponds to different elements. In this case, it is necessary to analyze the electrical circuit. Depending on the purpose of the diode, operating current, voltage, and some other parameters are assumed. According to the catalogs, it is recommended to try to identify the manufacturer, since the parameters are not significant, making it difficult to correctly identify the product.
In addition to the above, there are other information at times.Batch number, release date. Such measures are being taken, making it possible to track new product modifications. The design department issues corrective documentation with a number, date is present. And if the assembly workshop feature needs to be taken into account, practicing the changes made, the masters should read the markings.
If we assemble the equipment according to the new drawings (electrical circuits), using old parts, we will not get what was expected. Simply put, the product will go into failure, it is gratifying if this is a reversible process. Nothing will burn. But even in this case, the head of the workshop will certainly get a hat, the goods will have to be redone in terms of the unaccounted factor.
In addition to the diodes
On the basis of p-n-junctions created a billion modifications of the diodes. These include varicaps, zener diodes and even thyristors. Each family has its own characteristics, with diodes a lot of similarities. We see three global views:
- the outdated element base of today is of a relatively large size, clearly distinguishable markings formed by standard letters, numbers;
- glass cases with color symbols;
- SMD elements.
Analogs are selected on the basis of the conditions specified above: power dissipation, limiting voltage, current flow.
Any electronic circuit, regardless of the purpose, contains a large number of elements that regulate and control the flow of electric current through the wires. It is voltage regulation that plays an important role in the work of most modules, because a stable and long circuit operation depends on this parameter.
To stabilize the input voltage to the circuit, a special module was developed, which is literally the most important part of many devices. Import and domestic Zener diodes are used in circuits with different parameters, so there is a different marking of diodes on the body, which helps to determine and choose the right option.
A little more about the module and how it works
This is a semiconductor diode, which has the ability to produce a certain voltage value regardless of the current applied to it. This statement is not completely true for absolutely all options, because different models have different characteristics.If you apply a very strong current to an SMD module (or any other type) that is not designed for this, it will simply burn out. Therefore, the connection is made after installing the current-limiting resistor as a fuse, the value of the output current of which is equal to the maximum possible value of the input current to the stabilizer.
It is very similar to an ordinary semiconductor diode, but has a distinctive feature - its connection is the opposite. That is, the minus from the power source is fed to the anode of the Zener diode, and plus - to the cathode. Thus, the effect of the reverse branch is created, which provides its properties.
A similar module is a stabistor - it connects directly, without a fuse. It is used in cases when the input electricity parameters are precisely known and do not fluctuate, and the exact value is also obtained at the output.
Specifying Passport Specifications
They are the main indicators of domestic and imported Zener diodes, which must be guided in the selection of the Zener diode for a specific electronic circuit.
- UCT - indicates which nominal value the module is able to stabilize.
- ΔUCT - used to indicate the range of possible deviation of the incoming current as safe depreciation.
- ICT - parameters of the current that can flow when a rated voltage is applied to the module.
- ICT.MIN - shows the smallest value that can flow through the stabilizer. In this case, the flow voltage through the diode will be in the range UCT ± ΔUCT.
- ICT.MAX - the module is not able to withstand a higher voltage than this value.
The photo below shows the classic version. Please note that right on the housing shows where it has an anode and a cathode. A black (rarely gray) strip is drawn in a circle, which is located on the cathode side. The opposite side is the anode. This method is used for both domestic and imported diodes.
Additional marking of glass models
Diodes in glass cases have their own designations, which will be discussed later. They are so simple (unlike the options with plastic cases) that they are memorized almost immediately by heart, there is no need to use the reference book every time.
Color marking is used for plastic diodes, for example, for SOT-23. The solid module case has two flexible leads. On the case itself, next to the strip described above, several numbers are separated in the same color, separated by a Latin letter. Typically, the record has the form 1V3, 9V0, and so on, the variety allows you to choose any parameters by designation, as in SMD.
What does this code mark mean? It shows the stabilization voltage for which this element is designed. For example, 1V3 shows us that this value is 1.3 V, while the second option is 9 volts. Usually, the larger the body itself, the greater the stabilizing property it possesses. The photo below shows a Zener diode in a glass case with a 5.1 V cathode marking.
Proper selection of the parameters of the Zener diode will allow to obtain a stable current, which is fed from it to the circuit. Be sure to select such fuse parameters using the appropriate guide so that the input voltage does not spoil the part, it is desirable for it to be approximately in the middle of the UCT ± ΔUCT range.