Hello. I’m Ed Brorein. I’m an applications specialist for Agilent Technologies Systems
Product Division and I’ll be showing how to test the power conversion of efficiency
of a three-pin regulator. This testing is easily accomplished using an N6782 source
measure module for functional test. Together in the N6705B DC power analyzer mainframe,
this forms an ideal platform for testing voltage regulators and other similar types of power
management components.
Here I have breadboarded a three-pin voltage regulator, the input being connected to Channel
1 of the DC power analyzer and the output being connected to Channel 2 of the DC power
analyzer where I’ve installed two of our source measure modules, one providing power
to the device under test and the second providing a load function to the output of the regulator.
In my diagram, I’m displaying the input and output power of a voltage regulator as
it’s swept from minimum to maximum loading and efficiency is basically the ratio of the
output power to the input power and it’s displayed here by this dashed line.
To test this, we’re providing a source function with one source measure module installed within
our DC power analyzer mainframe to provide a fixed bias voltage to our ten-volt regulator
and we have a second N6782 source measure module operating as an electronic load pulling
power from our three-pin, ten-volt regulator, and we’ll have it sweep from a minimum to
maximum load function to be able to test the efficiency over a range of loading conditions.
To set up the DC power analyzer for doing the measurement of power efficiency, the voltage
regulator will use the 14585 control and analysis software.
The first thing we need to do is set up our instrument modules for sourcing and loading
operation and to do that we’ll select the Instrument Control tab on the left-hand side
to bring up our instrument control display. We will first set Output 1 up for sourcing
and I’ll go ahead and select Setting Voltage and Current Parameters in Output 2 and we
want to select it top rate is a two-quadrant power supply. It’s operating in voltage
priority and we’ve set it for 13 volts of output to power up our three-pin voltage regulator.
We now need to set up Output 2 to act as an electronic load. When we select Output 2,
and here we have the source settings for Output 2. We have selected CC Load Operation from
our list of preconfigured settings. This preconfigured list, the settings will ask you to quickly
and easily set up your various modules for different functions. We’ve set it up for
-100 microamps of current drain. Again, negative current because it’s acting as an electronic
load and this is our starting point for our loading condition.
Now we set up the DC bias conditions. Let me move the instrument control panel out of
the way again. We want to set up our arbitrary waveform function. So here on the top of our
screen, select our arbitrary waveform set up screen and what I want to do is apply an
arbitrary waveform to Output 2 current drain. So going down to the bottom of the screen
for Output 2, I have selected CDR Function for creating a load sweep on Output 2 and
I’m starting my load sweep at -100 microamps or DC bias starting condition and I’m sweeping
up to -50 milliamps of current loading. Again, I want to test the low level efficiency of
our regulator. We’re particularly interested in low level efficiency and I’m performing
the sweep over a two-second duration.
So now we’ve set up our arbitrary waveform to sweep the load on Output 2. We want to
go back and make measurements, so I’ll use the scope screen for doing that. So I’ll
select my Scope Screen tab on the top and now I need to set up my measurements. So down
on the bottom of the screen, I’m selecting Output 1 Power, which is our input power to
our device under test, and I selected Channel 2 Power, which is the output power of the
three channel – or three-pin voltage regulator.
And I’ve also set up a formula trace, which is a calculation for efficiency. Let me go
ahead and select on the Formula Trace and it’s a custom formula. We have custom formula
capability built in to this software for creating such traces and as you can see, I’m doing
a calculation of the output power to input power for determining efficiency.
So now I’ve set up all my measurement conditions. I also set up the triggering the measurement
to start on the arbitrary waveform sweep or the load sweep. So now all’s I need to do
is to start up the measurements. So going to this Scope button, I’ll start my acquisition
and it’s waiting for the ARB to start, so I’ll click on the ARB sweep and we’re
now acquiring our measurement.
So what I have displayed here is the yellow trace is the input power, the green trace
is our load power or output power. You can see it’s sweeping negative. That’s because
it’s a load. And then the red trace here is our efficiency curve we created from a
custom formula. And let me grab my Marker 1 here on the left-hand corner and I’ll
move it to say 50 milowatts of loading on Output 2. So here I’m roughly at 50 milowatts.
Down here at the bottom of the screen in the numerical results I have 50 milowatts of power
being drawn and I’m seeing down below it for the formula trace, 37.1 for the percentage
of efficiency.
So this is how you can measure the efficiency of load regulator using the N6705 and 14585
software. And so this is the way to make the measurements of the power efficiency of a
voltage regulator easily and quickly accomplished using the N6782 source measure module for
functional test together with the N6705 power analyzer and 14585 control and analysis software.
Thank you.