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In addition, peak pulse power consumption is also related to pulse waveform, duration, and ambient temperature. When the two poles of a TVS diode are subjected to a reverse transient high-energy shock, it can change the high impedance between the two poles to a low impedance at a rate of 10-12 second. The resistive material of the varistor is a semiconductor, so it is also a kind of semiconductor resistors. They are not easy to degrade, and the service life is long.Introduction TVS diode, also known as transient voltage suppressor, is a new type of commonly used high-efficiency circuit protection device, which has extremely fast response time (sub-nanosecond level) and relatively high surge-absorption capability. VWM is the maximum continuous working DC or pulse voltage of TVS. In Taiwan, varistors are called "surge absorbers" or sometimes referred to as "electric shock (surge) suppressors (absorbers)". (6) Clamp time TC TC is the time for the breakdown of the voltage VBR from zero to the minimum. Its full name is "Voltage Dependent Resistor" and is abbreviated as "VDR" or "Varistor".Parameters of TVS (1) Maximum reverse leakage current ID and rated reverse turn-off voltage VWM. It is a a voltage rise combination caused by temperature coefficients in a series resistors. Varistors have lower reliability, is easy to burn in, and has a short service life. TVS has many advantages such as small size, high power, fast response, no noise, low price, etc.
Working Principle of Varistors When the voltage applied to the varistor is below its threshold, the current flowing through it is extremely small, and the varistor at this time is equivalent to a resistor with an infinite value of resistance. When this reverse voltage is added between the two poles of TVS, it is in the reverse off-state, and the current flowing through it should be less than or equal to its maximum reverse leakage current ID. The size of C is in direct proportion to the current-carrying capacity of the TVS. As for the reaction speed, the reaction speed of the TVS tubes is very fast, which is ps level, while varistors&39; reaction speed is slow, which is ns level. TVS application of TVS TVS is mainly used for fast overvoltage protection of circuit components. For unipolar TVS, the time is less than 1×10-12 seconds; for bipolar TVS, the time should be less than 1×10-11 seconds. 3.I Varistors 1 Introduction of Varistor "Varistor" is a kind of resistor with nonlinear volt-ampere characteristics. The TVS clamp voltage is relatively low, but the price is higher.. When its two ends receive an instantaneous high-energy impact, it can change the impedance between the two ends from high impedance to low impedance at a very high speed to absorb a large instantaneous current and clamp the voltage across it to a predetermined value so as to protect the subsequent circuit components from transient high-voltage impact.Features of TVS TVS is a high-efficiency protection device in the form of a diode.
It can effectively protect against overvoltage surge caused by lightning or man-made operational mistakes like load switch. II TVS 1. 3. Compared with varistors, the TVS tubes&39; maximum clamping voltage that deviates from the breakdown voltage of is smaller, but the through-current capability is smaller than varistors. Because of its fast response, large transient power, low leakage current, small breakdown voltage deviation, easy control of clamping voltage, no damage limit, and small size, it has been widely used in computer systems, communication equipment, AC/ DC power supply, automotive, electronic ballasts, household appliances, instruments and apparatus (watt-hour meter), RS232/422/423/485, I/O, LAN, ISDN, ADSL, USB, MP3, PDAS, GPS, CDMA, GSM , digital camera protection, common mode / differential mode protection, RF coupling / IC drive receiving protection, motor electromagnetic interference suppression, audio / video input, sensors / transmissions, industrial control loops, relays, contactors&39; noise suppression and other fields. (3)Maximum voltage clamp VC and maximum peak pulse current IPP When the pulse peak current IPP with a duration of 20 microseconds flows through the TVS, the maximum peak voltage appearing between its two poles is VC. If there is a repetitive pulse in the circuit, the "accumulation" of the pulse power may damage the TVS. 2. The ratio of VC to VBR is called the clamping factor and its value is generally between 1. If the value of C is too large, signal will be attenuated. It "absorbs" surge signals up to several kilowatts. 4. (4) Capacitance C Capacitance C is determined by the TVS avalanche junction profile, and is measured at a specific frequency of 1 MHz. At a given maximum clamping voltage, the greater the power consumption PM is, the greater the surge current capability will be; at a given power consumption PM, the lower the clamping voltage VC is, the greater the surge current capability will be. (2) Minimum breakdown voltage VBR and breakdown current IR VBR is the smallest avalanche voltage of TVS. (5) Maximum peak pulse power consumption PM PM is the maximum peak pulse dissipation power that TVS can withstand. Therefore, zinc oxide varistor are kind of "II-VI oxide semiconductor". The reliability of the TVS tubes is higher. According to the dispersion degree between the VBR and its standard value, TVS can be divided into ±5% VBR and coexistence ±10% VBR. That is, when the voltage applied to the varistor is below its threshold, it is equivalent to a switch that is in the off-state. Advantages of Varistors (1)Various Sizes of Diameter.
Wide Range of Variable Resistors&39; Voltage: 18V-1800V; (3)Withstand Capability of Multiple Surge : standard, high surge, ultra high surge; (4)Large current handling and energy absorption capability; (5)Monomer flow rate can reach 70KA or even higher; (6)Fast response time (7)Low leakage current (8)Multiple lead forms: straight, bent and other special lead types (9)A variety of packaging formats: bulk, roll packaging 4. VC and IPP reflect the surge suppression capability of TVS devices. III Difference between Varistor and TVS Varistors have smaller size that occupying less space and lower cost. 2. The voltage is limited when the current is high, and the leakage current is large when the voltage is low. When the voltage increases, the resistance value in the circuit is reduced, and the current increases, eventually reducing the influence of the voltage on the circuit. Specified test pulse waveforms and the PM values of various TVS can be found in relevant product manuals. Function of Varistors The biggest advantage of the varistor is that when the threshold of the varistor itself is greater than the voltage from outside, the current flow value in the circuit become very small, and it will be equivalent to an out-of-operation valve.2 and 1.85 VBR; and for teristics of TVS tube are the same as those of voltage regulator tubes. That is, when the voltage applied to the varistor exceeds its threshold, it is equivalent to a closed-state switch. The leakage current is very small before breakdown, and after breakdown, TVS has the standard voltage regulation characteristic. "zinc oxide" (ZnO) varistors are widely used nowadays, and one ZnO varistor is composed of a divalent element zinc China prepaid meter Manufacturers (Zn) and a hexavalent element oxygen (O). At the same time, it will absorb several kilowatts of surge power, making the voltage between the two poles be clamped to a predetermined value, effectively protecting the precision components in the electronic circuit from various surge pulses. But varistors have poor nonlinear characteristics. Moreover, the transient pulses that TVS can withstand are not repeated. It is widely used in various fields such as household appliances, electronic instruments; instruments, precision equipment, computer systems, communication equipment, communication ports like RS232, 485 and CAN, ISDN protection, In addition, both have large capacitance(TVS tubes also have low capacitance products).01%.81 VBR. Varistors can withstand greater surge current, and the larger its volume is, the larger the surge current it can withstand, which can up to tens of kA to hundreds of kA. It is mainly used to clamp the voltage when the circuit is under overvoltage, and absorb excess current to protect sensitive devices. When the voltage applied to the varistor exceeds its threshold, the current flowing through it increases sharply, and the varistor is equivalent to a resistor with infinitely small resistance. The pulse repetition rate(the ratio of duration to pause time) specified by the device is 0.
Working Principle of Varistors When the voltage applied to the varistor is below its threshold, the current flowing through it is extremely small, and the varistor at this time is equivalent to a resistor with an infinite value of resistance. When this reverse voltage is added between the two poles of TVS, it is in the reverse off-state, and the current flowing through it should be less than or equal to its maximum reverse leakage current ID. The size of C is in direct proportion to the current-carrying capacity of the TVS. As for the reaction speed, the reaction speed of the TVS tubes is very fast, which is ps level, while varistors&39; reaction speed is slow, which is ns level. TVS application of TVS TVS is mainly used for fast overvoltage protection of circuit components. For unipolar TVS, the time is less than 1×10-12 seconds; for bipolar TVS, the time should be less than 1×10-11 seconds. 3.I Varistors 1 Introduction of Varistor "Varistor" is a kind of resistor with nonlinear volt-ampere characteristics. The TVS clamp voltage is relatively low, but the price is higher.. When its two ends receive an instantaneous high-energy impact, it can change the impedance between the two ends from high impedance to low impedance at a very high speed to absorb a large instantaneous current and clamp the voltage across it to a predetermined value so as to protect the subsequent circuit components from transient high-voltage impact.Features of TVS TVS is a high-efficiency protection device in the form of a diode.
It can effectively protect against overvoltage surge caused by lightning or man-made operational mistakes like load switch. II TVS 1. 3. Compared with varistors, the TVS tubes&39; maximum clamping voltage that deviates from the breakdown voltage of is smaller, but the through-current capability is smaller than varistors. Because of its fast response, large transient power, low leakage current, small breakdown voltage deviation, easy control of clamping voltage, no damage limit, and small size, it has been widely used in computer systems, communication equipment, AC/ DC power supply, automotive, electronic ballasts, household appliances, instruments and apparatus (watt-hour meter), RS232/422/423/485, I/O, LAN, ISDN, ADSL, USB, MP3, PDAS, GPS, CDMA, GSM , digital camera protection, common mode / differential mode protection, RF coupling / IC drive receiving protection, motor electromagnetic interference suppression, audio / video input, sensors / transmissions, industrial control loops, relays, contactors&39; noise suppression and other fields. (3)Maximum voltage clamp VC and maximum peak pulse current IPP When the pulse peak current IPP with a duration of 20 microseconds flows through the TVS, the maximum peak voltage appearing between its two poles is VC. If there is a repetitive pulse in the circuit, the "accumulation" of the pulse power may damage the TVS. 2. The ratio of VC to VBR is called the clamping factor and its value is generally between 1. If the value of C is too large, signal will be attenuated. It "absorbs" surge signals up to several kilowatts. 4. (4) Capacitance C Capacitance C is determined by the TVS avalanche junction profile, and is measured at a specific frequency of 1 MHz. At a given maximum clamping voltage, the greater the power consumption PM is, the greater the surge current capability will be; at a given power consumption PM, the lower the clamping voltage VC is, the greater the surge current capability will be. (2) Minimum breakdown voltage VBR and breakdown current IR VBR is the smallest avalanche voltage of TVS. (5) Maximum peak pulse power consumption PM PM is the maximum peak pulse dissipation power that TVS can withstand. Therefore, zinc oxide varistor are kind of "II-VI oxide semiconductor". The reliability of the TVS tubes is higher. According to the dispersion degree between the VBR and its standard value, TVS can be divided into ±5% VBR and coexistence ±10% VBR. That is, when the voltage applied to the varistor is below its threshold, it is equivalent to a switch that is in the off-state. Advantages of Varistors (1)Various Sizes of Diameter.
Wide Range of Variable Resistors&39; Voltage: 18V-1800V; (3)Withstand Capability of Multiple Surge : standard, high surge, ultra high surge; (4)Large current handling and energy absorption capability; (5)Monomer flow rate can reach 70KA or even higher; (6)Fast response time (7)Low leakage current (8)Multiple lead forms: straight, bent and other special lead types (9)A variety of packaging formats: bulk, roll packaging 4. VC and IPP reflect the surge suppression capability of TVS devices. III Difference between Varistor and TVS Varistors have smaller size that occupying less space and lower cost. 2. The voltage is limited when the current is high, and the leakage current is large when the voltage is low. When the voltage increases, the resistance value in the circuit is reduced, and the current increases, eventually reducing the influence of the voltage on the circuit. Specified test pulse waveforms and the PM values of various TVS can be found in relevant product manuals. Function of Varistors The biggest advantage of the varistor is that when the threshold of the varistor itself is greater than the voltage from outside, the current flow value in the circuit become very small, and it will be equivalent to an out-of-operation valve.2 and 1.85 VBR; and for teristics of TVS tube are the same as those of voltage regulator tubes. That is, when the voltage applied to the varistor exceeds its threshold, it is equivalent to a closed-state switch. The leakage current is very small before breakdown, and after breakdown, TVS has the standard voltage regulation characteristic. "zinc oxide" (ZnO) varistors are widely used nowadays, and one ZnO varistor is composed of a divalent element zinc China prepaid meter Manufacturers (Zn) and a hexavalent element oxygen (O). At the same time, it will absorb several kilowatts of surge power, making the voltage between the two poles be clamped to a predetermined value, effectively protecting the precision components in the electronic circuit from various surge pulses. But varistors have poor nonlinear characteristics. Moreover, the transient pulses that TVS can withstand are not repeated. It is widely used in various fields such as household appliances, electronic instruments; instruments, precision equipment, computer systems, communication equipment, communication ports like RS232, 485 and CAN, ISDN protection, In addition, both have large capacitance(TVS tubes also have low capacitance products).01%.81 VBR. Varistors can withstand greater surge current, and the larger its volume is, the larger the surge current it can withstand, which can up to tens of kA to hundreds of kA. It is mainly used to clamp the voltage when the circuit is under overvoltage, and absorb excess current to protect sensitive devices. When the voltage applied to the varistor exceeds its threshold, the current flowing through it increases sharply, and the varistor is equivalent to a resistor with infinitely small resistance. The pulse repetition rate(the ratio of duration to pause time) specified by the device is 0.
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