Hi. My name is Brad Jolly, and I’m an Applications
Engineer for Keysight Technologies. Today we’re going to talk about battery drain
analysis on low power IoT devices using a DC power analyzer with a source measure unit
and some special software. Long battery life is becoming especially important
for Internet of Things devices, and depending on what estimates you look at there will be
anywhere from 20 to 200 billion Internet of Things devices connected by the year 2020. One area is wearables, and customers want
battery life for convenience there. And another area for the IoT is remote sensors,
where customers often expect 10-year battery life or even more. The device we’re going to use today to test
battery drain is the N6705 DC power analyzer with the N6781 source measure unit, or SMU. It has four slots, up to 600 watts, and has
more than 30 modules that you can put in it. It features seamless ranging and 0.025% plus
eight nanoamps accuracy, up to 18 bits, and 500 million readings per day to log, with
zero burden voltage. The device under test, or DUT, that
we’re going to use today is a wearable device tracker. It has low power sleep modes and operating
modes for taking and storing measurements and RF communications. Let’s take a look at it on the N6705. Okay. Let’s take a look at the instrument. The first thing we see here is channel one,
and I can turn on or off the channel right here. There are four channels on the instrument. I can set up my source options over here,
my measurement options over here, and then the general instrument options can be set
over here. I can autoscale simply by pressing the trigger
button, and you’ll see that it autoscales. And then, I have knobs similar to an oscilloscope
here where I can adjust either the horizontal or vertical resolution. I can also move the waveform up or down and
right or left by using the appropriate knobs. In this case I’m just going to autoscale to
get it to a reasonable value. You’ll notice that right now it’s running
in scope view. I can also change it to meter view, where
I can see the individual channels as numeric values. Or, I can go back to the scope view. Let me go ahead and stop it. And then, if I want to zoom in, I can simply
take my horizontal and turn it right or left depending on which way I want it to go. And then, I can do the same thing vertically
depending on what level of detail I want to see. The real exciting part, however, is the 14585
software, which has features specifically defined for battery drain analysis. So, here’s the 14585 software, and it’s connected
to the same N6705 that we looked at a minute ago. I’m going to start the scope mode right now,
and you can see that it’s operating much like an oscilloscope would. There are also two other modes that we’re
going to look at today: the data logger mode and the CCDF mode. Let’s start with the scope mode. What I can do here is I can use autoscale,
and that will automatically scale in both X and Y. And if I want to change it, I can later go
over to here and change the horizontal scale, or I can change the vertical scale over here. Notice that I can also turn on the voltage
signal and/or the power. In this case, since it’s a battery-operated
device the current and the power are proportional, so I’m just going to leave this in current
mode only. Let me go ahead and stop the scope for right
now, and then I can zoom in using this button here. Click there and just go ahead and
zoom in. And you can see that I can get pretty good
detail, like so. So, that’s the Scope mode. Then, I can also scroll / pan right or left
right here, and I have the ability then to change to see how much I’m looking at at any
given time. The data logger mode will allow you to log
data, just as the name suggests. You simply specify the duration here, the
name for the file, and whether you also want to record the minimum and maximum values as
you go along. In this case I’m just going to leave it at
20 seconds, and let’s click on data log, and we’ll start data logging the session. And as you can see, it’s got a counter here
that tells how much time has passed. At the end of the data log session it will
automatically write this file here, as you’ll see in a second. So, if I click here for the browser, you’ll
notice that there is a “data log 8” file right there. What’s really useful for battery drain analysis
is the CCDF, or complementary cumulative distribution function. Let’s take a look at that. It’s very similar to the data log mode in
the sense that you specify the duration and the name of the file. Let’s go ahead and just run it. We can see the counter here. And it’s showing the cumulative distribution
function, but it’s showing it kind of upside down, and that’s why the “C” for complementary. Notice that it’s a log scale. So, the way you would read this is if you
look at it, it appears that 90% of this is 600 … about 500, excuse me, uA and less. So, what that tells you is about 90% of the
time the output is 500 uA and below. And that’s what you would expect for a device
like this, which has a large, sweep mode. You can, in fact, change this from log to
linear, but for an IoT device it’s pretty much a square, and so it’s usually most useful
to leave it as log. So, in conclusion, the N6705 along with the
N6781 SMU and the 14585 software is an easy to use solution to use for both sourcing and measuring. Its simple wiring, seamless ranging, and zero
burden voltage give you visual and numeric insights into battery drain characterization
of your device. Thank you for watching.

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