Cypress Type-C Barrel Connector Replacement + Infineon Buck DC/DC (Part 3)

Summary

This article walks you through the steps to test the CY4533 Type-C BCR & IR3894 under the load conditions from 1A to 12A.  In the previous article, I supplied power to the IR3894 using a bench top power supply.  For this set of experiments I will use a Type-C wall wart connected to the Cypress 4533 BCR development kit to supply power.

Test the BCR

The first thing that I do is connect the whole mess together like this:

Here is how it looks on my desk.  Note that the Keithey can measure current and voltage… but that I don’t have a way in this setup to measure either the voltage/current from the power supply or the current out of the CY4533

I step the output load from 1A to 12A in 1A increments.  I am super happy to see that the output voltage of the IR3894 is perfectly regulated to 1.198V.  It is also interesting to see that the Type-C power supply is able to keep the voltage within 3.25% of nominal even when I am using 12A on the IRDC3894 output (probably around 1.5A from the Type-C)

Measure the Input Current

In the previous article I used the current measurement from the Keithley bench top power supply.  In the setup above I don’t have a way to measure the actual input current.  To fix this put my new Keithley DAQ6510 in series with the IRDC3894 board.  Like this:

Then I step through the 1A-12A load conditions.  Once again the IR3894 provide a very well regulated voltage and current (exactly the same as before so I didn’t write them down)

Here is a table with the data from the previous post (without the Type-C power supply) versus the Type-C power supply.

2230-30-1 Power Supply With 6510 current meter in input path
Vin Iin Win Vout Iout Wout Eff Vin Iin Win Eff-C Loss
12 0.27 3.24 1.198 0 0 0%
12 0.129 1.548 1.198 0.998 1.195604 77% 11.91 0.129 1.53639 77.8% -0.6%
12 0.239 2.868 1.198 1.998 2.393604 83% 11.8 0.242 2.8556 83.8% -0.4%
12 0.345 4.14 1.198 2.998 3.591604 87% 11.7 0.352 4.1184 87.2% -0.5%
12 0.454 5.448 1.198 3.998 4.789604 88% 11.59 0.467 5.41253 88.5% -0.6%
12 0.564 6.768 1.198 4.999 5.988802 88% 11.47 0.586 6.72142 89.1% -0.6%
12 0.677 8.124 1.198 5.998 7.185604 88% 11.36 0.709 8.05424 89.2% -0.8%
12 0.792 9.504 1.198 6.998 8.383604 88% 11.25 0.837 9.41625 89.0% -0.8%
12 0.909 10.908 1.198 7.998 9.581604 88% 11.13 0.97 10.7961 88.8% -0.9%
12 1.029 12.348 1.198 8.998 10.779604 87% 10.95 1.115 12.20925 88.3% -1.0%
12 1.152 13.824 1.198 9.999 11.978802 87% 10.85 1.258 13.6493 87.8% -1.1%
12 1.277 15.324 1.198 10.998 13.175604 86% 10.8 1.401 15.1308 87.1% -1.1%
12 1.406 16.872 1.198 11.997 14.372406 85% 10.68 1.558 16.63944 86.4% -1.2%

These measurements use 1A/3A range on the Keithley DAQ6510 DMM, which means that they have a 100mΩ shunt resistor in series which drops the voltage by V=IR or about 0.1-ish volts.  This explains most of the difference from the Power Supply to the Type-C setup.

It is actually very interesting to look at the data to see the impact of lowering the input voltage on the efficiency of the IR3894.  It appears that at the highest load and lowest input voltage the efficiency is down by 1.2%

Watch the Sunrise

While I was sitting there at my desk thinking about what to do next, I decided that the best thing to do was go sit in my hottub and watch the sunrise on God’s country.

USB C Power Meter Tester

I was hoping to be able to measure the input current and voltage from the Type-C power supply so that I could calculate the efficiency of the CY4533 EZ BCR.  And as a result the efficiency of the whole system.  There wasn’t a place on the Type-C development kit to make these measurements, but the Cypress Apps manager for Type-C – Palani – said I should buy something like this from Amazon.

 

So I did.  You can plug it into Type-A or Type-C and it will tell you how much V/I are coming out.  In the picture below you can see 20.4v@0.11A

Even better it has a handy-dandy mode where it can display Chinese?

Here is a picture in my actual setup:

And a picture of the whole crazy setup.

Now I step through my 12 load conditions from 1A to 12A and record the V/I from the Fluke and the USB Power Tester.

Here is the data in table form with power and efficiency added.

Type C Power Tester
Vin Iin Win Eff-No Meter
11.99 0.15 1.7985 66.5%
11.95 0.26 3.107 77.0%
11.92 0.36 4.2912 83.7%
11.88 0.48 5.7024 84.0%
11.85 0.59 6.9915 85.7%
11.82 0.7 8.274 86.8%
11.79 0.82 9.6678 86.7%
11.75 0.94 11.045 86.8%
11.71 1.07 12.5297 86.0%
11.68 1.2 14.016 85.5%
11.64 1.33 15.4812 85.1%
11.6 1.46 16.936 84.9%

Next, I plot the new data with the previous two plots.  Obviously, it is screwed up.  I would bet money that the data points at 2A, 4A and 12A are wrong.  But, I don’t think that it is worthwhile to take steps to figure out the real current.  So, I suppose that is what you get from a $19 power meter.

Efficiency of CY4533 EZ-PD BCR

I had really wanted to measure the efficiency of the BCR setup.  To do that I needed to be able to measure the output power (V/I) and the input power (V/I).  Unfortunately the power meter doesn’t seem to be very good… so I suppose that I will have to wait to build my real board where I can install some power jumpers the real numbers.