A low power topology derived from flyback with active clamp based on a very simple transformer

This paper presents and analyzes a low power (10W) topology derived from flyback with active clamp based on very simple and low cost transformers. The main feature of this flyback topology is that the ratio between magnetizing inductance and the series inductance (leakage or integrated inductor) is very low (around 10/1). Operation of the topology is analyzed and several transformer configurations are considered. Performance of this topology are validated in three prototypes developed for an automotive application (V_IN =42V, V_OUT = 3.3V, I_OUT = 5A). The proposed solution achieves a promising trade-off between efficiency and cost in low power applications with medium or high input/output voltage ratio