Most laboratory power supplies (PSUs) offer a fixed maximum voltage and maximum current capability. For example, a 35V/20A PSU can supply up to 700 watts, but its power capability falls in direct proportion to the output voltage so  when being used at 12V, for example, the maximum power has reduced to 240W.  The TTi PowerFlex autorange system uses a modified form of mixed-mode regulation to provide higher levels of current when the voltage is set to lower values.  PowerFlex supplies have an auto-ranging or semi constant power characteristic so that the current capability rises as the voltage falls and offer a near constant power output over a limited range. Thus, for example, the QPX1200 can provide up to 60V or up to 50A within a total power limit of 1200W. This means that the maximum voltage and the maximum current are not available simultaneously and care must be taken when interpreting the specifications.