MHz Level Digital PFM Controller with Suppressed Time-Delay within Several Ten Nanoseconds

Recently, higher frequency operation, smaller size, and higher power density Switching-Mode Power Supplies (SMPS) are highly demanded. With advances in the technology of GaN, MHz level SMPS is becoming more realistic than ever[1-2]. Though, for the MHz level control circuit, the characteristic of analog devices, especially operation amplifier, is becoming overhead of its dynamic characteristics. Therefore, in this study, MHz and fast response digital PFM control circuit, composed of a comparator and some logic circuits, for the LLC current resonant DC-DC converter has been proposed. With the experimental results, the proposed controller the switching frequency can be varied from 0.8 MHz to 1.2 MHz 12V/1.5V DC-DC converter. Also, it was confirmed that the time-delay could be suppressed to several ten nanoseconds.