Useful Information | Special components in switching power supplies, do you know their types and uses?
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1. Fast recovery diode (FRD)----The reverse recovery time of the fast recovery diode is generally a few hundred nanoseconds, the forward voltage drop is 0.6V~1V, the forward current is a few amperes to several thousand amperes, and the reverse peak voltage can reach hundreds of volts to several thousand volts. It can be used as an output rectifier in a switching power supply and a blocking diode in the primary side clamp protection circuit.
▲ Fast recovery diode (FRD)
2. Ultrafast recovery diode (SRD)----The ultrafast recovery diode is developed based on the fast recovery diode. Its reverse recovery charge is further reduced, and the reverse recovery time can be as low as tens of nanoseconds. It can be used as a switching power supply adapter output rectifier, blocking diode, and rectifier in the feedback circuit.
▲ Superfast recovery diode (SRD)
3. Schottky diode (SBD)----The full name is Schottky barrier diode, which is a low-voltage, low-power, high-current, ultra-high-speed semiconductor power device. Its reverse recovery time can be as short as a few nanoseconds, the forward conduction voltage drop is only about 0.4V, and the rectified current can reach tens to hundreds of amperes. It is particularly suitable for use as a rectifier diode and freewheeling diode in the low-voltage output circuit of a switching power supply charger.
▲ Schottky diode (SBD)
4. Transient transformer suppression diode (TVS) - also known as transient voltage suppressor, it has an extremely fast response speed and stable clamping voltage. It is a new type of overvoltage protection device that can be used to protect switching power supply PWM integrated circuits, MOS power devices and other voltage-sensitive semiconductor devices.
▲ Transient voltage suppression diode (TVS)
5. Bidirectional trigger diode (DIAC)----also known as a two-terminal AC device, often used in conjunction with thyristors to form an output overvoltage protection circuit for the switching power supply transformer.
▲ Bidirectional trigger diode (DIAC)
1. Fuse resistor (FR)----Fuse resistor is also called insurance resistor or fusible resistor. It has the functions of both resistor and fuse. The fusing current ranges from tens of milliamperes to tens of amperes, and the fusing time ranges from a few seconds to tens of seconds.
▲ Fuse resistor (FR)
2. Resettable fuse tube (RF)----also known as resettable fuse, has the performance of automatic recovery and can be used repeatedly without maintenance or replacement.
▲ Resettable fuse tube (RF)
3. Soft-start resistor----It is a negative temperature coefficient thermistor (NTCR), which has the characteristics of low nominal resistance (only 1Ω~47Ω), high rated power (10~500W), and large operating current (1~10A), and is suitable as a starting protection component for switching power adapters.
▲ Soft start resistor
4. Varistor (VSR)----It has a wide operating voltage range (6V~3000V, divided into several grades), fast response to overvoltage pulses (a few nanoseconds to tens of nanoseconds), strong ability to withstand impact current (up to 100A~20Ka), small leakage current (less than a few microamperes to tens of microamperes), low resistance temperature coefficient (less than 0.05%/℃), and low price.
It can constitute the overvoltage protection circuit, lightning protection circuit, spark elimination circuit, surge voltage absorption circuit, etc. of the switching power supply adapter.
5. Digital potentiometer (DCP)----used in conjunction with an adjustable switching regulator to form a programmable switching regulator.
▲ Digital Potentiometer (DCP)
1. Unidirectional thyristor (SCR) --- used in conjunction with a bidirectional trigger diode to form a voltage protection circuit for a switching power adapter.
▲Single-direction thyristor (SCR)
2. Bidirectional thyristor (TRIAC)----can form an overvoltage protection circuit on the AC input side of the switching power supply.
▲ Bidirectional thyristor (TRIAC)
1. Optocoupler: The characteristic curve of the current transfer ratio (CTR) and the DC input current (If) of the linear optocoupler has good linearity. When transmitting small signals, the output and input can be linearly related, which is suitable for forming the optocoupler feedback circuit in the precision switching power supply and realizing the isolation between the secondary side and the primary side.
▲ Optocoupler
2. Filter: Also known as EMI filter, it is a bidirectional RF filter that can filter out external electromagnetic interference introduced from the AC line;
On the other hand, it can also prevent the switching power supply adapter from emitting noise interference to the outside, which can significantly improve the anti-interference ability of the switching power supply adapter and make the switching power supply comply with the electromagnetic compatibility (EMC) standard.
3. Adjustable precision shunt regulator: For example, TL431, which can be widely used in precision switching power adapters and chargers. It can also constitute voltage comparators, power supply voltage monitors, delay circuits, precision constant current sources, etc.
4. Magnetic beads: There are tubular, sheet-shaped magnetic beads and magnetic bead arrays, which can suppress the switching noise and spike interference of switching power adapters and chargers. There are tubular, sheet-shaped magnetic beads and magnetic bead arrays, which can suppress the switching noise and spike interference of switching power adapters and chargers.
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