Adaptive continuous Current Source Drivers to achieve efficiency improvement in wide load range

The concept of the adaptive drive currents is proposed for high frequency boost converters based on the continuous Current Source Drivers (CSDs). The idea of the adaptive CSD circuit is to build a current drive source of the power MOSFET that varies with the load current. When the load changes, the CSD gate drive current changes adaptively so that the switching loss reduction can be optimized. Compared to the traditional CSDs, the adaptive CSDs can achieve higher efficiency in a wide load range. A 40V input, 140V output and 1MHz boost converter was built to verify the advantages of the adaptive concept. The adaptive CSD improves the efficiency from 68.4% (12V drive voltage without adaptive control) to 74% (an improvement of 5.6%) at 5% load, and at 33% load, from 90.8% to 91.7% (an improvement of 0.9%). The efficiency improvement becomes more effective when the converter is in light load condition.