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Solution of 220V to 5V power supply
Release time:
2022-10-17 10:24
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220V to 5V power supply in the actual application of the circuit, the burned diode is the diode marked D2 in the circuit, the function of the diode in the circuit is backflow, the burned power resistance is r-9, then, let's learn the solution of 220V to 5V power supply together!
There are two ways to solve the problem of 220V to 5V power supply
1. Adjust circuit wiring
Replace the 1000 v super high speed recovery diode
Recovery of symptoms:
During the discharge process of d2ACDC, the reverse voltage is too large, the diode breaks down, the acdc output is short-circuited, the power circuit R9 current is too large, and the power is too high to burn out and open the circuit.
Knowledge supplement:
diode backflow effect
1. Working principle of freewheeling diode
Taking an induction coil as an example, when a current flows through the coil, an induced electromotive force is generated at both ends of the coil. After the current disappears, the induced electromotive force generates a reverse voltage on the components in the circuit. If the reverse voltage is higher than the reverse breakdown voltage of the element, the transistor and other elements will burn. If a diode is connected in anti-parallel at both ends of the coil, when the current in the coil disappears, the induced electromotive force generated in the coil will be consumed by the circuit composed of the diode and the coil, thereby ensuring the safety of other components in the circuit.
1) The role of the freewheeling diode in the positive excitation switching power supply
In the positive excitation switching power supply, when the MOS is turned off, the secondary side of the transformer supplies current to the outside through the energy stored in the inductor. A freewheeling diode is added to the secondary side of the transformer so that the inductance functions in this manner when loaded. After the MOS is turned off, the inductor, the load, and the freewheeling diode will create a path to transfer the energy in the inductor to the outside. Current can flow through the freewheeling diode only when there is an external load.
2) In the converter technology, what role does the freewheeling diode play in the circuit? In the electronic converter circuit, the single-phase bridge rectifier of the rectifier part is a single-phase rectifier circuit with more practical applications. Three-phase bridge rectifier is the power system, especially the generator excitation system application more way. A freewheeling diode is connected to both circuits. Its function is roughly the same. Take the single-phase bridge circuit as an example to illustrate. When the inductive load is connected to the control rectifier bridge, the induced current cannot change sharply. Therefore, during the cut-off period of the thyristor, when the thyristor is cut-off, dangerous overvoltage is generated at both ends of the inductive load. In order to prevent the phase change of the thyristor, the load
3) If the one-way half-wave controlled rectifier circuit has a large inductive load, why install a freewheeling diode?
When the negative half-cycle thyristor is turned off, the large inductive load with one-way half-wave controlled rectifier generates high back-induced electromotive force on the inductive load. The back-induced electromotive force is sufficient to destroy and burn the thyristor. After the freewheeling diode is added, the back-induced electromotive force can be released to the forward voltage drop (about 0.7v) of the diode.
2. The function of freewheeling diode of 220V to 5V power supply
A freewheeling diode is usually used with an energy storage element to prevent abrupt changes in voltage and current in the circuit and to provide a power dissipation path for the back electromotive force. The inductor provides continuous current to the load through it, avoiding sudden changes in load current and acting as a smooth current! In the supply source of the switching power supply of the switching power supply, a reflux circuit composed of a diode and a resistor connected in series can be seen. This circuit is connected in parallel with the primary side of the transformer.
When the switch tube is closed, the return circuit releases the energy stored in the transformer coil, which can prevent the induced voltage from damaging the switch tube.
3. Selection of Freewheeling Diode for 220V to 5V Power Supply
Fast recovery diodes, such as FR254, FR255, FR257, 1N5204, 1N5205, 1N5206, 1N5207, 1N5208, 1N5404, 1N5405, 5406, 5407, and 54084, freewheeling diode considerations
Freewheeling diodes are usually used in switching power supplies, relay circuits, thyristor circuits, IGBTIGBT and other circuits, and their applications are very extensive.
Please note the following when using 220V to 5V power supply.
1) The freewheeling diode is an effective means to prevent the high voltage generated by the self-induced potential from the DC coil during power failure from causing damage to related components.
2) Do not mistake the polarity of the freewheeling diode. Otherwise, it will cause a short circuit accident.
3) The freewheeling diode is always connected to the DC voltage in the reverse direction. That is, the cathode of the diode is connected to the anode of the direct current.
4) The freewheeling diode is a forward working conduction state, not a breakdown state or a high-speed switch state.
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