Current estimation circuit for discontinuous conduction mode flyback pulse-width modulation controller

Primary-side controlled flyback converter has been widely used in low-power and low-voltage products for its simple structure and low cost. As most applications require constant-current control, it is important for the integrated circuit to detect and express the output current accurately. This study proposes a novelty current detection and estimation circuit for primary-side controlled flyback controller. The circuit transmits the output current to voltage linearly with low power consumption and small layout area. Finally, a chip based on 0.6 μm complementary metal-oxide semiconductor process is fabricated using the current detection and estimation circuit in its constant-current loop to achieve constant output current.