In all our documents we specify only the +12V current because this is the worst case for all modules, i.e. there is no module that takes more current from the -12V supply than from the +12V supply. E.g. 50 mA current specification means 50mA are taken from +12V and 50 mA (or less) from -12V. All A-100 power supplies deliver the same current for +12V and -12V. E.g. the A-100PSU2 outputs 1200mA for +12V and 1200mA for -12V.

Consequently one simply has to add the specified module currents and check if the sum is less than 1200mA. Then the power supply is sufficient. Specification of both currents (+12V and -12V) would cause confusions and complicate calculations for the customers. We think that the solution to specify only the +12V current is the easiest way to calculate the current consumption and to find out if the power supply is sufficient. If you also run modules that require +5V and this voltage is generated by means of the 5V adapter A-100AD5 from the +12V supply the current for +5V has to be added to the +12V current !

New: From 2016 we will offer the new power supply A-100PSU3. This has asymmetrical values for the maximum current output (+12V: 2000mA / -12V: 1200mA). Therefore the currents are now specified for both +12V and -12V separately for all modules. As a rule each A-100 module consumes the same or less current at -12V compared to +12V. The Excel planning file contains also the current specs for all A-100 modules at a glance: System Planner (Excel™). The file contains also totals fields that show the total currents of all installed A-100 modules. The A-100PSU3 has also +5V available and the 5V adapter A-100AD5 is no longer required if you want to run modules that require +5V.