Series and parallel connection of piezoresistors.

In daily life, piezoresistors can also be used in series simply. That is, two piezoresistors with the same diameter can be connected in series, that is, the continuous working voltage, the piezoresistive voltage and the limiting voltage are added, and the flux index remains unchanged. For example, in high-voltage power surge arresters, it is generally required that the continuous working voltage is as high as thousands or tens of thousands of volts, that is, a plurality of ZnO varistor valves are stacked (connected in series).

At the same time, piezoresistors can also be connected in parallel, and the purpose of parallel connection is to obtain a larger flux, or to reduce the current density (under certain conditions) in the resistor body when the surge current peaks, so as to reduce the limiting voltage.

When a large flux is required and the voltage sensitive voltage is relatively low, the diameter/thickness ratio of the resistor is too large, which is difficult to realize in manufacturing technology. With the increase of the diameter of the resistor, the microscopic uniformity of the resistor becomes worse, so the flux cannot increase proportionally with the area of the resistor. At this time, it may be a reasonable and effective solution to connect resistors with smaller diameter in parallel.

Because of the existence of high nonlinearity, the parallel connection of varistor chips needs to be very careful. Usually, only after careful matching and parallel connection of resistors with the same parameters can the current be evenly distributed among the resistors. In view of this situation, our company can provide users with paired resistors.

 In addition, the piezoresistors are connected longitudinally, and when paired piezoresistors with the same parameters are used, the voltage difference appearing in the transverse direction can be very small when the impact invades.

The varistor can also be connected in series with gas discharge devices such as gas discharge tubes, air gaps and micro-discharge gaps. The normal operation of this series combination generally needs to meet two basic conditions:

(1) after g ignition, under the upper limit of system voltage, the current in varistor MY should be less than the arc holding current of g to ensure the arc extinguishing of g;

(2) The upper limit of system voltage should be lower than the DC breakdown voltage of gas discharge device G;

 This series combination has the characteristics of small capacitance, high working frequency, small leakage current, good safety, etc., and there is no aging problem of varistor MY under the system voltage, so it has high reliability, but it also has the problem of "yielding voltage" caused by slow response of gas discharge devices.

The varistor can also be connected in parallel with the gas discharge tube to reduce the impulse ignition voltage of the gas discharge tube.

In many cases, varistor should not be directly used in the protection of high-frequency signal lines, and its junction capacitance is generally in the order of several hundred to several thousand pf. When applied in the protection of AC circuits, because its junction capacitance will increase leakage current, it should be fully considered when designing protective circuits.