Electronic devices need power, of course. Specifically, virtually all modern circuits are based around semiconductor chips (integrated circuits) and displays, and these parts each require one or more stable DC voltages, typically in the 1–5V range. In most intelligent products and particularly in the case of products that use rechargeable batteries, a fair bit of effort goes into the design, debugging, and testing of power supplies.
Much literature exists on the details of power supply design, but less is available on the system-level issues. Casual decisions are often made about which batteries, chargers, power supply chips, and other power components to use. Then, months later, design engineers find themselves caught in a rat hole when a major problem crops up that requires a significant redesign, such as finding out that a system’s circuitry simply cannot recharge a deeply discharged battery and a new battery with at least a little charge needs to be swapped in. More knowledge and thinking at the front end of a project can help us avoid many of these rat holes.
To better understand this chapter’s material, let’s begin with a high-level look at the fundamentals, and at some of the challenges we face.
There are two basic categories of design decisions that must be made when designing an electronic product:
What are our sources of power: battery, electrical outlet, car power plug, etc.?
How will we convert the voltage(s) supplied by the source(s) ...