What are the parameters of a rectifier diode?

From commonly usedRectifier diodesA7 look at the parameters:

Form factor: SOD-123FL

Forward average current: 1A

Reverse repetition peak voltage: 1000V

Forward (non-repeating) inrush current.

25A Forward Peak Voltage:

Reverse leakage current: 5UA, 50UA

Junction temperature. - 55°c to + 150°c

Storage temperature: -55°C to +150°C visible, rectifier diode parameters are: forward average current, reverse repetitive peak voltage, forward inrush current, forward peak voltage, reverse leakage current, package form, junction temperature, etc.

A7 diode package.

A7 diode.

1. Maximum rectifier current:

It refers to the maximum forward current value that is allowed to pass through the MDD diode when it works continuously for a long time, and its value is the same as the PN junction.

area and external heat dissipation conditions. This is because the current passing through the tube heats up the die.

When the temperature rises and the temperature exceeds the allowable limit (about 141 for silicon tubes and 90 for germanium tubes), the die will overheat and be damaged. Therefore, under the specified heat dissipation conditions, the maximum rectification current value of the MDD diode should not be exceeded in the use of the MDD diode. For example, the commonly used IN4001 4007 germanium diode is rated for forward operation of 1A.

2. Maximum reverse working voltage:

When the reverse voltage applied to both ends of the MDD diode reaches a certain value, the tube will break down and lose its unidirectional conductivity. In order to ensure safe use, the maximum reverse operating voltage value is specified. For example, the reverse withstand voltage of the IN4001 diode is 50V, and the reverse withstand voltage of the In4007 is 1000V.

3. Reverse current:

Reverse current refers to the reverse current that flows through the MDD diode under the action of the specified temperature and the maximum reverse voltage. The smaller the reverse current, the better the unidirectional conductivity of the tube. It is important to note that the reverse current is closely related to temperature, and that the reverse current doubles for every 10 increases in temperature.

For example, if the reverse current of the 2AP1 germanium MDD diode is 250UA at 25, the temperature rises to 35, the reverse current will rise to 500UA, and so on, at 75, its reverse current has reached 8MA, which not only loses the unidirectional conductive characteristics, but also overheats the tube and damages. For another example, the reverse current of the 2CP10 silicon MDD diode is only 5UA at 25, and the reverse current is only 160UA when the temperature rises to 75. Therefore, silicon MDD diodes have better stability than germanium MDD diodes at high temperatures.

Rectifier diodes

The reverse recovery time is the time interval between the current passing through the zero point from the forward direction to the specified low value. It is an important technical index to measure the performance of high-frequency freewheeling and rectifier devices.

The normal fast MDD ultra-fast recovery diode will reflect the recovery time parameter, the unit is nanometer (ns), the faster the recovery time, the better, and the higher the efficiency.

Rectifier diodes are unidirectional and are mainly used in circuits such as rectification, voltage regulation, and mixing. This article introduces the parameters and selection principles of rectifier diodes and regulated rectifier diodes.

The main parameters are: the maximum permissible reverse voltage applied at both ends of the rectifier diode. If this value is higher, the reverse current (IR) increases dramatically, and the unidirectional conductivity of the rectifier diode is destroyed, causing reverse breakdown.

Usually half of the reverse breakdown voltage (VB) is taken as (VR). For example, the VR of 1N4001 is 50V, and the VR of 1N4007 is 1ooov.

The choice of rectifier diode mainly depends on the required withstand voltage and current, in addition to the package shape, the most important thing is the withstand voltage and current of the rectifier diode.

If it is within 1A, the 1N400X series can be selected, including 1NN4002 and 1N4007, and the rectifier diodes with withstand voltages of 30V, 50V, 100V, 200V, 400V, 600V, 800V, and 1000V are selected.

If the current is greater than 1A but not more than 3A, the 1N580X series can be selected, including 1N N N5402 1N5408, and the withstand voltage is 50V, 100V, 200V, 300V, 400V, 500V, 600V, 800V, and 1000V respectively.

If the current is more than 3A, a Schottky diode with a high current (the maximum current is more than 100A.) There are too many specific models of Schottky diodes to list them one by one).

Forward rectification current, reverse maximum withstand voltage, frequency (mainly for high-frequency rectification), heat dissipation conditions, package form.

Selection of rectifier diode.

Rectifier diodes are generally planar silicon diodes, which are used in various power supply rectifier circuits.

When selecting a rectifier diode, the parameters such as the maximum rectifier current, the maximum reverse working current, the cut-off frequency and the reverse recovery time should be considered.

A rectifier diode used in a common series regulated power supply circuit.

(1) Maximum average rectification current if: refers to the maximum forward average current allowed to pass through the diode when it is working for a long time. This current is determined by the junction area of the p-n junction and the heat dissipation conditions.

When using, it should be noted that the average current through the diode should not be greater than this value, and the heat dissipation conditions should be met. For example, the 1N4000 series diode has an IF of 1A.

2) Maximum reverse working voltage vr: refers to the maximum reverse voltage that can be applied at both ends of the diode. If this value is higher, the reverse current (IR) increases dramatically, and the unidirectional conductivity of the diode is destroyed, causing a reverse breakdown.

Usually half of the reverse breakdown voltage (VB) is taken as (VR). For example, the VR of 1N4001 is 50V, 1N4002-1N4006 are 100V, 200V, 400V, 600V, and 800V, respectively, and the VR of 1N4007 is 1000V

3) Maximum reverse current IR: It is the reverse current that the diode is allowed to flow through at the highest reverse working voltage, and this parameter reflects the unidirectional electrical conductivity of the diode. Therefore, the lower the current value, the better the quality of the diode.

4) Breakdown voltage vb: refers to the voltage value at the sharp bending point of the reverse volt-ampere characteristic curve of the diode. When the reverse is a soft characteristic, it refers to the voltage value under a given reverse leakage current.

5) Maximum working frequency fm: It is the highest working frequency of the diode under normal conditions. It is mainly determined by the junction capacitance and diffusion capacitance of the PN junction, and if the operating frequency exceeds FM, the unidirectional conductivity of the diode will not be well reflected.

For example, the FM of the 1N4000 series diode is 3kHz. Fast recovery diodes are also used for the rectification of alternating currents with higher frequencies, e.g. in switching power supplies.

6) Reverse recovery time trr: refers to the reverse recovery time under the specified load, forward current and maximum reverse transient voltage.

7) Zero bias capacitance CO: refers to the sum of the capacitance of the diffusion capacitance and the junction capacitor when the voltage at both ends of the diode is zero. It is worth noting that due to the limitations of the manufacturing process, even the same model of diode has a large discrete parameter.

The parameters given in the manual are often a range, and if the test conditions change, the corresponding parameters will also change, e.g. the IR of the 1N5200 series silicon rectifier diode is less than 10UA at 25°C and less than 500UA at 100°C.

A rectifier diode is a semiconductor device that converts alternating current energy into direct current energy. The rectifier diode has obvious unidirectional conductivity, is a large-area power device, large junction capacitance, low working frequency, generally in tens of kilohertz, reverse voltage from 25V to 3000V.

Common models are: silicon rectifier diode VZ=6 to, pzm = silicon rectifier diode vz=to, pzm = silicon rectifier diode 50V, silicon rectifier diode 100V, silicon rectifier diode 200V, silicon rectifier diode 1000V, silicon rectifier diode 200V, silicon rectifier diode 1000V, silicon rectifier diode 50V, silicon rectifier diode 100V, silicon rectifier diode 200V, silicon rectifier diode 600V, silicon rectifier diode 1000V, 3A.

The low-voltage and high-current diodes used in automobiles should be used.

If you can't see the model number, you can check it from the other headlight.

The role of a rectifier diode is to convert alternating current into direct current. Common rectifier diodes include 1N N5401 and other models. The text symbol in the circuit is "V" or "VD".

The diode rectifier circuit is generally connected to the secondary output of the power transformer or the 220V AC mains, usually a bridge rectifier circuit composed of four diodes. Its post-stage is the filter, after the AC is rectified, the AC component is required to be filtered as cleanly as possible, so the filter capacitors are all large-capacity electrolytic capacitors, and the general capacity is hundreds of micro-methods to thousands of micro-methods. The rectifier circuit operates at a low frequency and the current through the diode is large, so silicon contact rectifier diodes are used.

Rectifier diodes can be inspected with a multimeter. During maintenance, if the measured forward resistance of the diode is too large or the reverse resistance is too small, it indicates that the rectification efficiency of the diode is not high; If the forward resistance is measured to be infinity, it means that the diode is internally open; If the measured reverse resistance is close to zero, the diode has broken down.

In power circuits, you will also find a component called a full-wave rectifier bridge (referred to as a full-bridge assembly). The so-called full-bridge assembly is a kind of rectifier assembly that encapsulates four rectifier diodes together according to the connection mode of full-wave bridge rectifier circuit, which is mainly divided into four types: cuboidal, cylindrical, flat and notch-square, as shown in the figure, wherein, "for the AC input end" and "for the DC output terminal.

If you use 4 rectifier diodes of different types to form a rectifier bridge, it can be used, but it is best not to use it this way, because the parameters are inconsistent, the impact on the output is relatively large, and it will also increase the instability factor or reduce the efficiency. In this way, it depends on whether your backstage circuit has high requirements for the power supply.

Measuring the diode with the diode position of the digital multimeter: When measuring the diode, use the gear of the diode of the multimeter. If the red pen is connected to the anode (positive) pole of the diode, and the black pen is connected to the negative pole of the diode, the diode is in positive deviation and has a certain value display.

If the red pen is connected to the diode cathode, and the black pen is connected to the diode anode, the diode is in reverse deviation, and the high position is displayed as "1" or a large value, then the diode is good.

If the values are small both times during the measurement, the diode will be short-circuited internally; If both measurements are large or the high position is "1", the diode is internally open.

Summary. The diode has no unit, only the resistance, capacitance (its unit farad) inductance, (unit henry) has a unit.

The diode has no unit, only the resistance, capacitance (its unit farad) inductance, (unit henry) has a unit.

I'm sorry I don't understand, but can you elaborate on that?

A diode, a device with two electrodes that allows current to flow in a single direction, is used in many ways to rectify the current that allows it to flow in a single direction. Varactor diodes (VAFIC diodes) are used as electronic tunable capacitors.

The current directivity of most diodes is often referred to as "rectifying". The most common function of a diode is to allow only the source current to pass through a single direction (known as forward bias) and to block it in reverse direction (known as reverse bias). Therefore, the diode can be thought of as an electronic version of the check valve.

early vacuum electron diodes; It is an electronic device that is capable of conducting electric current in one direction. Inside the semiconductor diode, there is a PN junction with two lead terminals, and this electronic device has the conductivity of unidirectional current in the direction of the applied voltage. Generally speaking, a crystal diode is a p-n junction interface formed by the sintering of p-type semiconductors and n-type semiconductors.

A space charge layer is formed on both sides of its interface, which constitutes a self-built electric field. When the applied voltage is equal to zero, the diffusion current caused by the concentration difference between the carriers on both sides of the p-n junction and the drift current caused by the self-generated electric field are equal and the diode is in equilibrium, which is also the characteristic of the diode under normal conditions. Early diodes contained "whisker crystals ("cat's whisker"crystals)" and vacuum tubes (known in the UK as "thermionic valves"), most of the most common diodes today use semiconductor materials such as silicon or germanium.

<> rectifier diodes use the unidirectional conductivity of the PN junction to turn alternating current into pulsating direct current. The leakage current of rectifier diodes is large, and most of them are diodes packaged with surface contact materials. In addition, in addition to the previously introduced parameters, the parameters of the rectifier diode also include the maximum rectifier current, which refers to the maximum current value allowed by the rectifier diode for a long period of time.

It is the main parameter of the rectifier diode and is the main basis for the selection of rectifier diodes.

It is because of this characteristic that the working principle of the rectifier diode is so accurate.