This reference design showcases three non-isolated AC/DC power supply topologies for line-powered applications such as residential circuit interrupters, circuit breakers, home automation equipment and appliances for < 100 mA. The three topologies are:
- Off-line switcher using inductor
- AC line regulator using switched capacitor (active-clamped capacitor-drop based power supply)
- Capacitive-drop regulator (cap-drop power supply)
The trade-off between efficiency, start-up time and solution size is done across architectures for various input and output conditions. The design methodology, test data and comparison is included for system designers to quickly evaluate and customize their solution.
- Off-line switcher using the UCC28880: High efficiency architecture using a buck converter simplifies the design covering universal input voltage – applications requiring fast startup (< 2 ms), small footprint or need to meet stringent surge requirements
- Switching capacitor-drop power supply using the TPS7A78: Inductor-less architecture customized for a narrow input voltage range – high efficiency solution for low current (< 30 mA) and a single chip solution with integrated active rectifier and LDO
- Capacitor-drop (cap-drop) power supply using an LDO: Simplified solution with passive components and LDO – low-cost solution with low efficiency, high startup time and large footprint