Low-power applications such as e-meters (electricity or energy meters) often require a simple ac line-powered supply where a 3.3-V rail powers a microcontroller and charges a lithium-ion battery to 4.2 V. You can implement this with a mains-frequency power transformer or with a more complicated ac-dc (offline) power supply. Both approaches have well-known disadvantages related to a combination of weight, size, and complexity. Two simpler options are a full-wave capacitor-drop circuit with the
Register to view the full article
By registering on Electronic Design now, you'll not only gain access to premium content, you'll also become part of an exclusive, robust global engineering community!
Participate in Expert and Reader driven Q&A's
Start your own conversation by commenting on any article or blog
Download high-quality content including the highly anticipated Salary & Career Report