Support Forum

Many voltage sources (source meters and power supplies) provide current limiting functionality to limit current levels to prevent damaging electronic devices or altering fault characteristics. Current limiting works by automatically reducing output voltage until current output no longer exceeds the limit.

All current limiting voltage sources require time (specified by slew rate) to reduce output voltage when limiting current. Slew rate is typically very short and is usually measured in units of microseconds. During this short time however, it is possible for high current to flow through an electronic device, altering the fault or damaging the device. The slew rate of source meters is typically much faster than power supplies and therefore, the potential for damage is less likely.

Current limiting should not be relied upon to protect devices and should be used only as a backup if fault resistance decreases during testing, resulting in higher current draw. Source voltage should be set so that current flow is less than the current limit.