Switcher Efficiency Sweeper


     By substituting a single component such as the inductor in a switching power supply and then measuring efficiency at a large number of input and output conditions, a quick comparison can be made between a known good part and prospective alternates.  This efficiency sweeper has a 0-10V programmable UUT input supply and a 0-1A programmable UUT output load.
GUI      The hardware is controlled by the Efficiency Sweeper controller utility in the Calculators program which collects the test data and then writes it a pre-sorted block into an Excel ready CSV file that can then be plotted as a surface chart.  A dropout tolerance check is available to flag unexpected operation that may still result in reasonable efficiency data.  The set input voltage, UUT output voltage and set output current are all checked against their expected value.  If any of the three are out of spec, the efficiency for that data point is reported as 0% the out of tolerance, the event is counted and the cause is displayed.
Data output - final      The final data from the calibrated unit gives a smooth curve of efficiency for many input voltages and output load currents, in this case 192 data points (16 x 12).  By using Excel to generate a surface plot, it's very easy to see where efficiency suffers or unwanted operation occurs.   The last page shows the GUI dropout tolerance check at work.
Data output - proto      The proto data was from a first go-around tester using a crude programmable power supply and a binary weighted resistor load bank.  No calibration was done on the sense inputs since the results were going to be compared as relative to a baseline device in a hurry.  The calculations at low current would peak over 100% due to the limited resolution but the result was still useful for doing the comparison.

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This page last updated on August 12, 2010