The following figure illustrates a test system with a capacitance of 200 pF added to simulate cable capacitance. Also, the external load has been identified as the input to a high-impedance DMM. Even the input to the DMM presents a substantial capacitive load. The addition of the cable to connect the switch to the load increases this load further. The total load capacitance is 300 pF.

Test System with Protection

The following table shows lifetime test results for a circuit with no protection and for a circuit with 200 of protection resistance.

Rp () Lifetime (cycles)
0 160,000
200 1,500,000

This example shows nearly a 10-to-1 increase in lifetime when a protective series impedance is used to isolate the switch from the capacitive load.