Automated test system for the characterization of switching regulators using VXI instrumentation

This paper introduces a computer-based virtual instrument (VI) which can perform an automated test on Pulse Width Modulator (PWM) IC's and a dynamical characterization of DC-DC switching converters. Such VI has been implemented using programmable GPIB instruments and VXI modules, performing both signal routing and data acquisition. The first section of the VI is devoted to the test of the PWM devices used as duty cycle controllers in the design of switched DC-DC converters. The second section of the designed VI can be used to make a dynamical characterization of PWM-based switching DC-DC converter by means of a complete set of measurements, such as input to output and control to output transfer function, input admittance, etc. As an example, both electrical characteristics over normal operating conditions of the SG3524 and TL1451AC PWM and a dynamical characterization of a PWM-based Buck converter have been obtained.