Diode characteristics and applications

In almost all electronic circuits, it is necessary to use semiconductor diode, which in many circuits play an important role, it is the birth of one of the first semiconductor device, its applications are very extensive.

Diode Diode works works

Crystal diode as a p-type semiconductor and n-type semiconductor pn junction formed in its interface on both sides of the formation of space charge layer, and built self-built electric field. Crystal diode as a p-type semiconductor and n-type semiconductor pn junction formed in its interface on both sides of the formation of space charge layer,
and built self-built electric field. When there is no applied voltage, due to set out on both sides of pn junction Concentration difference caused by the proliferation of current and self-built electric field induced drift currents are equal but in the power balance. When there is no applied voltage, due to pn junction on both sides of carrier concentration caused by the proliferation of poor self-built electric current and the drift caused by electric currents are equal and in balance.

While it has a positive voltage bias, the external electric field and self-built electric field between the role of suppressing consumption so that carrier diffusion current increases caused by the forward current. While it has a positive voltage bias, the external electric field and self-built electric field between the role of suppressing consumption so that carrier diffusion current increases caused by the forward current.

When there has been speculation reverse voltage bias, the external electric field and self-built electric field to further strengthen, the formation of certain reverse voltage range has nothing to do with the reverse-bias voltage value of reverse saturation current I0. When there has been speculation reverse voltage bias, the external electric field and self-built electric field to further strengthen, the formation of certain reverse voltage range has nothing to do with the reverse-bias voltage value of reverse saturation current I0.

When the applied reverse voltage of a high to a certain extent, pn junction space-charge layer electric field strength to reach the critical values of carrier multiplication process, producing a large number of electron-hole pairs produced a great reverse breakdown current value , called the diode breakdown phenomenon. When the applied reverse voltage of a high to a certain extent, pn junction space-charge layer electric field strength to reach the critical values of carrier multiplication process, producing a large number of electron-hole pairs produced a great reverse breakdown current value, called the diode breakdown phenomenon.

Types of Diode Diode type

There are many types of diodes, in accordance with the semiconductor material used can be divided into germanium diode (Ge tube) and silicon diode (Si tube). There are many types of diodes, in accordance with the semiconductor material used can be divided into germanium diode (Ge tube) and silicon diode (Si tube). According to their different uses can be divided into detection diode, rectifier diodes, zener diode, switching diode. According to their different uses can be divided into detection diode, rectifier diodes, Zener Diodes, Switching Diodes, etc .. in accordance with the die structure, and can be divided into point-contact diode, surface-contact diodes and planar diode. In accordance with the die structure, and can be divided into point-contact diode, surface-contact diodes and planar diode. Point-contact diode is to use a very thin metal wire down on clean semiconductor wafer surface electrified with pulse current , so Touch wire at one end and the chip firmly sintered together to form a "PN junction." Point-contact diode is to use a very thin metal wire down on clean semiconductor wafer surface electrified with pulse current, so that one end of the wire touch with the chip firmly sintered together to form a "PN junction." Because it is point contact, only allows a smaller current (no more than tens of mA), applicable to high-frequency low current circuits, such as the radio detection and so on. Because it is point contact, only allows a smaller current (no more than tens of mA), applicable to high-frequency low current circuits, such as the radio detection and so on.

Surface-contact diode "PN junction," the larger, allows a larger current (a few to dozens of An An), mainly used to transform alternating current into direct current "rectifier" circuit. Surface-contact diode "PN junction," the larger, allows a larger current (a few to dozens of An An), mainly used to transform alternating current into direct current "rectifier" circuit.

Planar diode is a specially designed silicon diode, not only through the strong current, and the performance is stable and reliable, used for switching, pulse and high frequency circuits. Planar diode is a specially designed silicon diode, not only through the strong current, and the performance is stable and reliable, used for switching, pulse and high frequency circuits.

Diode electrical properties Conductive characteristics of diode

The most important characteristics of diode is a one-way conductivity. The most important characteristics of diode is a one-way conductivity. In the circuit, current flows only from the positive diode, negative outflow. In the circuit, current flows only from the positive diode, negative outflow. The following simple experiment shows the forward diode characteristics and reverse characteristics. The following simple experiment shows the forward diode characteristics and reverse characteristics.

1, positive characteristics of 1, positive characteristics of

In electronic circuits, the diode cathode connected to the high potential side connected to the low potential negative side diode will turn, this connection method, known as forward bias. In electronic circuits, the diode cathode connected to the high potential side connected to the low potential negative side diode will turn, this connection method, known as forward bias. Must make it clear that when added to the diode forward voltage is very small at both ends, diode is still can not lead pass, flow through the diode forward current is very weak. Have to say that, when added to the diode forward voltage is very small at both ends, diodes still can not turn, flows through the diode forward current is very weak. Only when the forward voltage reaches a certain value (this value is called "threshold voltage", germanium tubes is about 0.2V, silicon tube of about 0.6V) after the diode in order to directly guide them pass. Only when the forward voltage reaches a certain value (this is called the "threshold voltage", germanium tubes is about 0.2V, silicon tube of about 0.6V) after the diode in order to directly guide them pass. After the diode turn-on at both ends voltage remained essentially unchanged (germanium tubes is about 0.3V, silicon tube of about 0.7V), known as the diode's "forward voltage drop." After the turn-on voltage across the diode remained essentially unchanged (germanium tubes is about 0.3V, silicon tube of about 0.7V), known as the diode's "forward voltage drop."

2, the reverse features 2, reverse characteristics

In electronic circuits, the diode cathode connected to the low potential side, the negative electrode connected to the high potential side, this time almost no diode current flows through, this time diode is cut-off state, such a connection is called reverse bias. In electronic circuits, the diode cathode connected to the low potential side, the negative electrode connected to the high potential side, this time almost no diode current flows through, this time diode is cut-off state, such a connection is called reverse bias. diode is reverse biased, we still have a weak reverse current flow through the diode, known as leakage current. Diode is reverse biased, we still have a weak reverse current flow through the diode, known as leakage current. When the reverse voltage across the diode increases to a certain value, the reverse current will rapidly increase, diodes will lose one-way conductive features, this state is called the breakdown diode. When the reverse voltage across the diode increases to a certain value, the reverse current will rapidly increase, diodes will lose one-way electrical properties, this state is called the breakdown diode.

The main parameters of diode The main parameters of diode

Diode is used to indicate the performance good or bad and scope of application of technical indicators, known as the diode parameters. Diode is used to indicate the performance good or bad and scope of application of technical indicators, known as the diode parameters. Different types of diodes have different parameters. Different types of diodes have different parameters. For starters, we must understand the following main parameters: For starters, we must understand the following main parameters:

1, rated operating current of positive 1, rated operating current forward

Refers to the diode allows the long-term continuous work, the maximum forward current value. Refers to the diode allows the long-term continuous work, the maximum forward current value. Because the current through the tube when you will die of fever, increase in temperature, temperatures in excess of the permissible limits (silicon tube of about 140, germanium tube 90 or so) when the , it will cause overheating and damage the die. Because the current through the tube when you will die of fever, increase in temperature, temperatures in excess of the permissible limits (silicon tube of about 140, germanium tube 90 or so), they will make the die overheating damage. Therefore, the diodes used Do not exceed rated diode forward current value of work. Therefore, the diodes use should not exceed the forward diode rated operating current value. For example, the commonly used IN4001-4007-type germanium diode forward the work of the rated current of 1A. For example, the commonly used IN4001-4007-type germanium diode forward the work of the rated current of 1A.

2, the maximum reverse voltage 2, the maximum reverse voltage

Added to the diode reverse voltage across the high-to a certain value, will be tube breakdown, loss of one-way conductivity. Added to the diode reverse voltage across the high-to a certain value, will be tube breakdown, loss of one-way conductivity. In order to ensure the safe use of work provides for a maximum reverse voltage. In order to ensure safe, provides for a maximum reverse voltage value. For example, IN4001 diode reverse voltage of 50V, IN4007 reverse voltage of 1000V. For example, IN4001 diode reverse voltage of 50V, IN4007 reverse voltage of 1000V.

3, reverse current 3, reverse current

Diode reverse current is the specified temperature and the maximum reverse voltage under the action of the reverse current flow through the diode. Diode reverse current is the specified temperature and the maximum reverse voltage under the action of the reverse current flow through the diode. Reverse current the smaller the pipe the better the conductivity in one direction. Reverse current smaller the tube the better the conductivity in one direction. It is noteworthy that the reverse current has a close relationship with the temperature around the temperature is increased by 10, double the reverse current increases. It is noteworthy that the reverse current has a close relationship with the temperature around the temperature is increased by 10, double the reverse current increases. For example, 2AP1-type germanium diodes, at 25, when the reverse current if it is 250uA, the temperature rises to 35, reverse current will increase to 500uA, and so on, at 75, it has reached the reverse current of 8mA, not only lost the one-way electrical properties, but also so that the tube overheating damage. For example, 2AP1-type germanium diodes, at 25, when the reverse current if it is 250uA, the temperature rises to 35, reverse current will rise to 500uA, and so on, at 75, it has reached the reverse current of 8mA, not only lost its one-way electrical properties, but also to make the tube overheating damage. Again, 2CP10 silicon diodes 25 when the reverse current of only 5uA, the temperature rises to 75, the reverse current is nothing but 160uA. Again, 2CP10 silicon diodes 25 when the reverse current of only 5uA, the temperature rises to 75, the reverse current is nothing but 160uA. So silicon diodes at high temperatures than germanium diodes have a good stability. Therefore, silicon diodes at high temperatures than germanium diode has a good stability.

The quality of test diodes The quality of test diodes

Beginners in amateur conditions, you can use the multimeter diode test the performance of good or bad. Beginners in amateur conditions, you can use the multimeter diode test the performance of good or bad. Multimeter before the test should first change-over switch appropriated for Ohm file RX1K stalls (be careful not to use RX1 file, so as not to burn too much current diode) , and then red, black and two tables pen a short circuit to zero ohms. Before the test should first switch multimeter appropriated for Ohm file RX1K stalls (be careful not to use RX1 file, so as not to burn too much current diode), then red, black and two tables pen a short circuit to zero ohms.

1, positive characteristics of test 1, Forward Characteristics Test

The multimeter pen black table (table cathode) take the touch diode cathode, and red table pen (table negative) take the touch diode cathode. The multimeter pen black table (table cathode) take the touch diode cathode, and red table pen (table negative) take the touch diode cathode. not placed a value of 0 if it stopped in the middle of the scale plate, when the resistance value is the diode forward resistance, positive resistance in general the smaller the better. If the 表针 it is not placed in the value of 0 scale plate parked in the middle, when the resistance is the diode forward resistance, positive resistance in general the smaller the better. If the forward resistance of 0 value, indicating short-circuit damage to the die If the forward resistance value close to infinity, indicating the die circuit. If the forward resistance of 0 value, indicating short-circuit damage to die, if the forward resistance value close to infinity, indicating the die circuit. Short-circuit and open circuit of the tube can not be used. Short-circuit and open circuit of the tube can not be used.

2, reverse property test 2, reverse Characteristics Test

To 10000 and the table red table touch pen take the diode cathode, black table touch pen take the diode cathode, if refers to the value of infinity or near infinity value, the tube is qualified. To 10000 and the table red table touch pen take the diode cathode, black table touch pen take the diode cathode, if refers to the value of infinity or near infinity value, the tube is qualified.