0190-19421 CONSTANT VOLTAGE/CURRENT LIMITING SUPPLIES
Current limiting supplies provide overcurrent protection for applications where a constant voltage is the only requirement. There are two basic types of current limiting circuits used today; conventional current limit and current foldback.
Current Limit
Current limiting is similar to constant current except that the current feedback loop uses fewer stages of gain.A sharp knee indicates continuous regulation through the crossover region while a rounded knee denotes loss of regulation before the crossover value is reached. To avoid any possibility of performance degradation, the current limit crossover point must be set somewhat higher than the maximum expected operating current when using a Constant Voltage/Current Limiting (CV/CL) Supply.
CV/CL supplies employ either a fixed current limit or a continuously variable limit. In either case the change in the output current of the supply from the point where current limiting action is first incurred to the current value at short circuit is customarily 3% to 5% of the current rating of the power supply.
By their current limiting action, CV/CL supplies prevent damage to components within the power supply and will also protect the load provided that the current limiting crossover point is set at a current value that the load can handle without damage. All of Agilent's current limiting supplies are self-restoring; that is, when the overload is removed or corrected, the output voltage is automatically restored to the previously set value.
