Abstract
This paper aims to present a combined, DPWM based control method and spectrum flattening technique of a mid-power range DC-DC converter. The research goal was to obtain sustainable results in both switching control and EMI compliance, using one 8 or 16 bits RISC MCU as main control unit running a performance- and speed-optimized firmware. This approach describes a hybrid method preserving the good dynamic performances of an analog switching regulator controller and adding the flexibility of controlling the output voltage by adjusting the duty cycle value of a DPWM signal and thus controlling the average voltage value of the signal applied in the feedback circuit of a DC-DC converter. Beside the feedback control of the DC-DC converter an active EMI reduction technique applies on this design by taking advantage on the constant-frequency, forced-continuous current mode architecture of the switching regulator controller, which allows its frequency to be synchronized with an external control clock dithered by a software implemented pseudo-random sequence generator. All this efforts concludes in reducing the noise power considerably at the main peak and at the next peaks.
