Pulse Resistors

This is a small note to indicate what are pulse resistors, what type of resistors are used as pulse resistors and what are their specifications. this type of resistors are specifically used in the path where they are subjected to compliance tests which induce high power pulses as part of the test.

There is a growing need in the electronics systems to get certified. Also many countries have stringent regulations in place to import products. The need for EFT, Surge and ESD testing is a must for the products irrespective of the category. One of the requirement in this tests are the pulse handling capacity of the components used. In case of a surge test, the series resistor is very important and must limit the current and also protect from the over voltage. In our normal designs we don't think of using such pulse withstanding resistors but it is always preferable to use them. Ceramic composition resistors are good at handling both high voltage and high energy pulses. But the main disadvantage of Ceramic composition resistors is the cost. Also, the stability of Ceramic composition resistors is lesser compared to film resistors.

The important specifications of this pulse withstanding resistors is similar to normal resistors.

1. Power Rating
2. Tolerance
3. voltage (LEV - Limiting element votlage)
4. Operating Temperature
5. Pulse withstanding capability

Considering the fact that many designs are preferring to use SMD resistors in their applications instead of axial resistors, pulse resistors are available in SMD packages as well. S2-100RF1 from Riedon is one example of the pulse withstanding resistors in SMD form.  Typical test pulses that pulse resistors should withstand are defined in IEC 60115-1.