Digitally Controlled Point of Load Converter with Very Fast Transient Response

Lars Tønnes Jakobsen, Michael Andreas E. Andersen

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This paper presents a new Digital Self-Oscillating Modulator (DiSOM) that allows the duty cycle to be changed instantly. The DiSOM modulator is shown to have variable switching that is a function of the duty cycle. Compared to a more traditional digital PWM modulator based on a counter and comparator the DiSOM modulator allows the sampling frequency of the output voltage control loop to be higher than the switching frequency of the power converter, typically a DC/DC converter. The features of the DiSOM modulator makes it possible to design a digitally controlled DC/DC converter with linear voltage mode control and very fast transient response. The DiSOM modulator is combined with a digital PID compensator algorithm is implemented in a hybrid CPLD/FPGA and is used to control a synchronous Buck converter, which is used in typical Point of Load applications. The computational time is only three clock cycles from the time the A/D converter result is read by the control algorithm to the time the duty cycle command is updated. A typical POL converter has been built and the experimental results show that the transient response of the converter is very fast. The output voltage overshoot is only 2.5% of the nominal output voltage when a load step of 50% - 100% of nominal output current is applied to the converter. The settling time is approximately 8 PWM cycles.
Original languageEnglish
Title of host publication12th European Conference on Power Electronics and Applications
Publication date2007
ISBN (Print)9789075815108
Publication statusPublished - 2007
Event12th European Conference on Power Electronics and Applications - Aalborg, Denmark
Duration: 2 Sep 20075 Sep 2007
Conference number: 12


Conference12th European Conference on Power Electronics and Applications
Internet address

Bibliographical note

Copyright: 2007 IEEE. Personal use of this material is permitted. However, permission to reprint/republish this material for advertising or promotional purposes or for creating new collective works for resale or redistribution to servers or lists, or to reuse any copyrighted component of this work in other works must be obtained from the IEEE


  • DC power supply
  • Pulse Width Modulation(PWM)
  • Signal Processing
  • Converter control

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