Application principle of the pressure sensitive resistor
The voltage sensitive resistor is a kind of element which has the function of transient voltage suppression. It can be used in place of the combination of transient suppression diode, Qi Na diode and capacitor. The voltage sensitive resistor can protect the circuit of the IC and other equipment, prevent the damage to them due to electrostatic discharge, surge and other transient current (such as lightning strike). The varistor is connected to the protected equipment or IC circuit, when the voltage is higher than a certain value, the varistor resistance decreased rapidly, the conduction current, thereby protecting the IC or electrical equipment; when the voltage is lower than the varistor voltage value, varistor resistance is extremely high, almost open. It will not affect the normal work of the electrical equipment or devices. Application of varistor varistor can be used widely, the main feeder line DC power supply, AC power supply, low frequency signal line, belt feeding. From handheld electronic products to industrial equipment, the specifications and dimensions of a variety of. With the wide use of portable electronic products, especially mobile phone, laptop computer, PDA, digital cameras, medical instruments, the speed of the circuit system is more demanding, and requires lower operating voltage, the voltage sensitive resistor presents smaller, higher performance requirements. As a result, the surface assembly of the pressure sensitive resistor components are beginning to emerge in large numbers, and its annual sales growth rate is higher than the lead wire more than twice the number of pressure sensitive resistors.
2002 is expected to increase the market growth rate of 13%, which, multilayer chip voltage sensitive resistor market growth rate of 20% ~ 30%, the radial lead product growth rate of 5% ~ 10%. The demand mainly comes from the power supply equipment, including DC power supply equipment, uninterrupted power supply, as well as the new consumer electronic products, such as digital audio / video equipment, video games, digital cameras, etc.. Chip voltage dependent resistors have accounted for 40% of the total sales of the U.S. market to 45%. (0402) the most popular type of chip voltage sensitive resistors. 0201 size of the product is not yet available. AVX company‘s 0402 chip voltage sensitive resistors are 5.6V, 9V, 14V and 18V, and several other voltage range of products, their rated power of 50mJ, typical capacitance range from 90pF (18V products) ~ 360pF (5.6V products). MaidaDevelopment also manufactures varistor chip series, but currently only launched a non standard size of the product, 1210, 1206, 0805, 0603 and 0402 of the products being production.
Littelfuse company introduced 0201 products by the end of 2000. The company has launched AVX and Littelfuse Voltage Suppressor Array, such as AVX launched Multiguard series of Multilayer Ceramic Transient Voltage Suppressor Array (i.e. varistor array) has been accepted by the market. Can save up to 50% of the board space, 75% of the production and assembly costs. Multiguad series of 1206 type specifications. Among them, there is a kind of dual components using 0805 specifications, the working voltage is 5.6V, 9V, 14V and 18V, etc., the rated power of 0.1J. AVX company launched Transfeed multilayer ceramic transient voltage suppressor. The product integrated the company‘s Transguard series of pressure sensitive resistor and Feedthru series capacitor / filter function. Adopt 0805 specifications. The component has a performance advantage, faster turn-on time (or response time, in 200ps ~ 250ps) and smaller parallel coefficients.
Littelfuse manufacturing of MLN surge array components 1206 specifications, built-in 4 multilayer voltage sensitive resistors. The product of ESD IEC67100042 reached level fourth. Including its main characteristics: inductance (1nH), adjacent channel crosstalk typical 50dB (1MHz frequency), the rated voltage working condition, leakage current of 5A, voltage up to 18V, the capacitance value can be specified by the user. The MLN patch assembly can be used for board level ESD protection, and the application fields include hand held products, computer products, industrial and medical equipment, etc..
EPCOS company launched a T4NA230XFV integrated surge suppressor, containing two varistor and a short circuit device. The product is used for the protection of communications equipment at one side of the telecommunications center and the subscriber line.