What is a TLP test?

Transmission line pulse (TLP) is a way to test device behavior in the current and time domain of ESD events.

Conventional models for the ESD immunity tests of a device include a human body model (HBM), machine model (MM), and charge device model (CDM) whereas a system-level ESD immunity test is specified by IEC 61000-4-2 and other standards. Different test techniques may provide different results because of differences in the prescribed signal rise time.

A TLP test generates a rectangular wave by charging a floating cable to a predetermined voltage and discharging it into a device under test (DUT). The pulse width and the rise time can be changed easily by changing the cable length and the filter characteristics.

The TLP test uses short pulses with a width on the order of nanoseconds, making it possible to obtain I-V characteristics in the high-voltage, high-current region (i.e., ESD voltage/current region) without causing thermal destruction.
The TLP test serves as an aid for ESD design because it makes it possible not only to compare the ESD protection performance of different TVS diodes, but also to compare the ESD tolerance of a TVS diode with the I-V curve of an IC to be protected.