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19 April 2018

IoT Digital Power Management and Power Integrity

The half-bridge output current from each DC-DC phase is known as the inductor current
Figure 1: The half-bridge output
current from each DC-DC phase
is known as the inductor current
An Internet of Things (IoT) device derives its power either from a 12-V DC supply or from a battery. In either case, power is fed to one or more power rails that operate at different voltages. These rails power the CPU and other functional blocks on the PC board. In this post, we'll take a look at how to examine an IoT's power supply for proper digital power management implementation and for power integrity.

16 April 2018

Anatomy of an IoT Device

IoTs include SOCs, DDR, DPM ICs, wireless, and MCUs
Figure 1: IoTs include SOCs, DDR,
DPM ICs, wireless, and MCUs
There's already more Internet of Things (IoT) devices deployed than there are humans on Earth. That gap will increase radically in coming years, and the explosion in IoT devices means a commensurate explosion in the need for debugging tools. So what's in an IoT device to debug, anyway?

04 April 2018

Debugging the IoT

Chances are you're already using the IoT in various ways
Figure 1: Chances are you're already
using the IoT in various ways
By now, we're all familiar with the phrase "Internet of Things" (IoT); some of you may be directly involved with that concept on some level as a designer/technologist. Here, we'll begin a series of posts on the IoT with some broad discussion of what it's all about, and then segue into how oscilloscopes and related hardware/software are among the best tools available for design and debug of IoT-related devices.

15 March 2018

An Example of Three-Phase Power Measurements

Screen capture of a 10-s acquisition of AC input and PWM output of a 480-V motor drive
Figure 1: Screen capture of a 10-s acquisition of AC input
and PWM output of a 480-V motor drive
To follow up on our last post on three-phase power calculations, and to wrap up this series of posts on the fundamentals of power, we'll walk through an example of a set of three-phase power measurements. We'll base our discussion on a single screen capture of measurements taken on a 480-V motor drive with 480-V AC input and 480-V maximum drive output. For this example, we used a Teledyne LeCroy Motor Drive Analyzer.

14 March 2018

Three-Phase Power Calculations

Three-phase power calculations entail summing of the individual phases's power calculations
Figure 1: Three-phase power calculations
entail summing of the individual
phases's power calculations
Until now, our discussions of power calculations have encompassed only single-phase systems with one voltage and one current. Now we'll turn to three-phase systems, which can be thought of as a collection of three single-phase systems. In general, three-phase power calculations are a simple summing of the individual phase power calculations and should be balanced across all three phases.

13 March 2018

Power Calculations for Distorted Waveforms

The sum of many sine waves, of varying amplitudes and frequencies, comprises the rough- looking square wave shown in red
Figure 1: The sum of many sine waves, of varying
amplitudes and frequencies, comprises the rough-
looking square wave shown in red
Our last post covered basic power calculations for pure sine waves, which are useful only up to a point in that pure sine waves are rather rare in the real world. Almost any real-world waveform carries some amount of distortion. Because distorted voltage and current waveforms comprise multiple frequencies, the relatively simple techniques used to measure power for pure, single-frequency sine waves no longer apply.

09 March 2018

Power Calculations for Pure Sine Waves

 For a purely resistive load, power = voltage * current, with both vectors in phase
Figure 1: For a purely resistive load,
power = voltage * current, with both vectors in phase
Wouldn't it be wonderful if every sine wave we encountered in the real world was pure, with no distortion? It sure would make life easier. Alas, it's pretty much never the case. But in reviewing sinusoidal power calculations, it's best that we begin with the simplest case: a single, pure sinusoidal line voltage and single, pure sinusoidal line current supplying a linear load.