1N4007 Basic Data and Applications

1N4007 is general silicon rectifier diode with the a plastic package form of DO-41. It is widely used in various AC-to-DC rectifier circuits, and also used in bridge rectifier circuits. 1n4007 utilizes the unidirectional conductivity of diodes to convert alternating current into pulsed direct current in a single direction. So it plays an important role in many circuits.

1N4007 is a kind of rectifier diodes. In the case of low power, the forward voltage is about 0.6 to 0.8 V. In the case of high power, the forward voltage drop often reaches about 1V. The reverse recovery time is at the us level and can only be used in low-frequency circuits.

Rectifier diodes are the most widely used in electronics. Rectification makes full use of the unidirectional conductivity of the diode. The AC signal is converted into a pulsating DC signal by blocking the negative half cycle of the waveform. It is usually used in combination with a capacitor. The diode is connected in series and the capacitor is connected in parallel. The function of the capacitor is to make the output pulse smoother through charging and discharging, which is closer to DC, and is a filter capacitor. According to needs, it is divided into half-wave rectification and full-wave rectification.

"1"stands for 1 junction.

"N" is the U.S. EIA (Electronic Industries Association) registration mark, and a diode with this letter indicates that it has been registered in the U.S. EIA.

"4007" is the registration number of the device in the U.S. EIA.

· Standard Recovery

· Strong forward surge bearing capacity: 30A

· Maximum forward average rectified current: 1.0A

· The limit parameter is VRM≥50V

· Maximum reverse withstand voltage: 1000V

· Maximum reverse leakage current: 5uA

· Forward voltage drop: 0.7V

· Maximum reverse peak current: 30uA

· Typical thermal resistance: 65°C/W

· Typical junction capacitance: 15pF

· Working temperature: -50℃～+150℃

· Low reverse leakage current

· Strong forward surge tolerance

· High temperature welding guarantee

· 250℃/10 seconds, 0.375" (9.5mm) lead length.

(The lead can withstand 5 pounds (2.3kg) of pulling force.)

· Terminal: Tinned axial lead

· Polarity: The color ring end is cathode

· Installation location: Any

1N4007 can be replaced by 1n5408 and 1n5399. If reverse recovery time is not required, FR107 and UF4007 can also be used.

If better performance is required, some supplement tubes can be used instead, such as quick recovery Schottky diodes, which can improve the power supply performance, such as 1SS294, BAT54A, 1N5818, SB540, MBR1645 and so on. These can greatly improve the low frequency response performance of the power supply.

1N4007 and SM4007 belong to the same model series. The difference lies in the model prefix, that is, the difference is reflected in the package form. 4007 is a rectifier diode commonly used in low-frequency power supplies. Its current is 1A and its withstand voltage is 1000V. 1N4007 belongs to the 1N4000 series of rectifier diodes. Similar models of this series include 1N4001, 1N4002, 1N4003, 1N4004, 1N4005,1N4006, etc. And the main difference between them is the withstand voltage.

The commonly used package of 1N4007 is dual in-line package, which is DO-14 package. But there are different packages for diodes of the same model series, such as SMA chip package and SOD123 chip package. Different packages of the same type of diode will use the model prefix to distinguish them, and most of the SMD components will indicate the model by code. For example, the code of 4007 for SMA package is M7, and the code for 4007 of SOD123 package is generally A7. Another difference in the model prefix will be used to represent different manufacturers.

DO-41 Package

Although the parameters of different packages of the same type diodes are basically the same, the relationship between withstand voltage and current needs to be considered when using diodes. There may be slight differences in the manufacturing mechanism of the diodes of different sub-packages, which will have some difference in parameters, such as thermal resistance.

The slow recovery power frequency rectifier tube 1N4007 is used to rectify the power supply winding of the main control IC to solve the problem of high bias voltage in the multi-winding system. Using a certain IC as a 5-way output DVB power supply, during the mass production process, it is found that the defective rate was high, and the symptom is that the power supply doesn’t work or hiccups. After test, it is found that the power supply voltage of the IC is too high, and the IC overvoltage protection mechanism is triggered.

Everyone knows that for a multi-output power supply, to achieve a good cross-regulation rate is quite a test of the transformer design skills, and it is inevitable that the bias supply winding voltage is too high. When multiple sets of power supplies have been mass-produced, redesigning the transformer is obviously not a good solution.

IC Control Circuit

Also the increase in the resistance of the rectifier diode in series is limited. Because its main function is to filter out the peak voltage, and what causes the IC to protect is the high bias winding voltage. At this time, the charm of the slow rectifier tube is reflected. Change the fast recovery diode HER107 to 1N4007, the problem is solved perfectly. Due to the load is not large, there will be no major problems with the normal use of the circuit.

The RCD absorption circuit in Flyback uses the slow tube 1N4007 to solve the leakage inductance peak voltage stress and EMI radiation problems on the main switch. Because if the transformer design is unreasonable and the leakage inductance is large, the leakage inductance voltage will be large when the switch tube is off. And meanwhile, the oscillation time will be longer, resulting in a relatively large MOS voltage stress and excessive EMI radiation.

RCD Absorption Circuit

With 1N4007, the drain oscillation is perfectly suppressed and the peak value is greatly reduced, thereby reducing the voltage stress of the MOS and greatly improving EMI. The voltage peak of R1 will become larger, because 1N4007 reverse recovery time is longer, so the electricity of C1 will be caused by backflow. Experiments have shown that reducing the loss of R2 will increase the efficiency of the power supply, but the actual measurement has not found an improvement in efficiency, so here we will keep neutral. However, the energy reflux actually exists, and both theoretical analysis and actual measurement results have shown it. That is, the 1N4007 will generate more heat, so this solution is suitable for low-power Flyback, high-power is not recommended. If in the design, the MOS voltage stress is relatively large and the total EMI exceeds the standard, you can also try to use a 1N4007.

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