Load switches are used to enable/disable power to selected ICs or circuit subsections. Although they don’t get much attention, they are useful for both saving power as well as management of multiple power rails. This FAQ will discuss their function, basic design, advanced IC implementations, and additional benefits of IC load switches. Q: What is […]
basics
Voice-coil actuators, Part 2: Application issues
Part 1 looked at the basic of the VCA. Part 2 looks at operation in more detail along with applications, as well as a comparison to the solenoid. Q: What equation governs the behavior of a VCA? A: As with most magnetic-coil devices, it’s the Lorentz force equation. This shows that the force generated is […]
Voice-coil actuators, Part 1: Principle basics
When designers need a modest amount of motion and power, they naturally think of a motor. That makes sense since there’s often a brushed, brushless, or stepper motor that can meet the objectives, sometimes with some necessary add-on gearing. Or they may think of a solenoid for impact-type linear motion. This FAQ looks at another […]
Wireless charging, Part 2: implementation
Part 1 of this FAQ looked at the overall context of wireless charging of personal devices. This part looks in more detail at the approaches to wireless charging and the implementation specifics. Q: What approaches are available for wireless charging? A: There are three basic topologies: single-coil inductive, multi-coil inductive, and resonant. Q: What are […]
Wireless charging, Part 1: context
Wireless charging of devices is a hot and growing area. This FAQ explores the rationale and options for implementing this form of energy transfer, storage, and charging. Q: What is wireless charging? A: It consists of two functions which are closely linked. The first is the transmission of electricals power wirelessly from a transmitting source […]
Parasitic capacitance, inductance, and displacement current
When two electrical conductors are physically close, carry a charge, and there’s a voltage potential between them, they create a virtual capacitor between them, even if the conductors are insulated. The virtual capacitor between them is known as parasitic or stray capacitance. This can happen anywhere but is most troublesome between traces on printed circuit […]
Load lines, Part 2: The DC load line and AC operation
In Part 1 of this FAQ, we looked at the basic DC load line for a simple, basic common-emitter transistor configuration. Part 2 looks at how this graph is used to maintain the linear AC performance of the amplifier configuration. Note that the term “quiescent mode” or “quiescent state” is also used with ICs and […]
Load lines, Part 1: The basic transistor DC load line
There are concepts and terms in basic analog circuits which may not be familiar to designers who work primarily with digital circuits. Yet digital circuits are really specialized versions of analog ones, so these “old” analog principles play a large although somewhat invisible role. Part 1 of this FAQ discusses DC load-line basics, while Part […]
DC power rails, Part 2: Single-rail and multi-rail management
Part 1 of this FAQ discussed development and designation of basic DC power rails. Part 2 looks at key specifications of these rails, and management of single- and multi-rail systems. Q: What’s an important point to remember whenever discussing voltage? A: The tendency is to say “this voltage rail is at such-and-such voltage” or “the […]
DC power rails, Part 1: Basics and designations
Most circuits and systems now run on DC-voltage power rails. That simple statement glosses over the wide range of voltages, issues of tolerance and ripple, designations of these rails, and management of both single and multiple rails. This FAQ will explore those uses. Q: Why are DC rails so important? A: They are the pathways […]
