Voltage at PPK without external supply

RE: Voltage at PPK without external supply

Stian Røed Hafskjold — Mon, 03 Feb 2020 14:53:55 GMT

Yes, I'm afraid that's not possible.

RE: Voltage at PPK without external supply

KilianL — Thu, 30 Jan 2020 14:11:06 GMT

I don't know what's different today, but now I can see the exact voltage that I apply to the External supply clamps also at my DUT. The strange thing is, that the PPK seems to get ints energy also from the external supply, 14 mA at 3V? I thought I can put a battery to the external supply and make long term lifetime tests with a battery capacity, but when the PPK is using the same energy that's not possible.

RE: Voltage at PPK without external supply

Stian Røed Hafskjold — Wed, 29 Jan 2020 12:26:11 GMT

If you soldered SB32 there will be a short between the supply on the DK and the external supply. If the voltage difference is high there will flow a lot of current and you will probably break some components.

If the following steps do not work, it sounds to me that some components on the PPK are broken because of the supply short.

Set the "Power select" switch on the PPK to the "External" position
Set the "DUT" switch on the PPK to the"External" position
Connect SWD cable from DK to PPK
Connect USB cable to both DK and PPK
Supply 3V on the "External supply" pin
Finally, you can open up the PPK software

RE: Voltage at PPK without external supply

Mishka — Wed, 29 Jan 2020 10:49:48 GMT

I believe in order to make it work you have to supply externally regulated voltage to the External Supply.

RE: Voltage at PPK without external supply

KilianL — Wed, 29 Jan 2020 10:41:29 GMT

I already desoldered this bridge. Now I can only establish a connection between DK and PPK in "Reg" position. Otherwise the PPK seems not be be recognized by the DK. That was the initial reason to solder SB32.

So in Ext. position the PPK is "dead" an the software is not able to launch.

RE: Voltage at PPK without external supply

Stian Røed Hafskjold — Wed, 29 Jan 2020 10:22:11 GMT

KilianL I think I know the problem now. In your original question I see that you wrote "soldered the SB32 in the DK". This is connecting VDD to the SWD external voltage sense pin. This pin is sensing the voltage on the PPK, and on the PPK this line is connected to VDD as well. So by soldering SB32, you power the PPK directly from the DK VDD which is 2.8V. So de-solder SB32 and see if that fixes it.

RE: Voltage at PPK without external supply

Stian Røed Hafskjold — Wed, 29 Jan 2020 10:16:55 GMT

When the PPK is connected on top of the DK, the regulator switch has to be in the DK position. The reg or external modes do not work properly in this mode. The DK is supplying 2.8V to the PPK and DUT.

RE: Voltage at PPK without external supply

KilianL — Wed, 29 Jan 2020 08:36:07 GMT

I'm using PPK Rev. 1.1.0, PK Software 2.3.1 and the Firmware of PPK I just erased and flashed with the latest firmware. My issue remains, the PPK is back powering my external power supply with 2,85V. I can switch the DUT on and off with the software but External or Reg is powering the DUT always with 2,7 V or above. Lower is not possible.

RE: Voltage at PPK without external supply

Mishka — Tue, 28 Jan 2020 22:36:30 GMT

This perfectly explains my case - I connected the PPK on top of the DK. After moving it out of the DK it started to work properly (1.8 - 3.6V external supply is required though). Thank you!

BTW, my PPK revision is 1.1.0, model PCA63511, dated 2018.26. Software: 2.3.1 (macOS nRF Connect 3.3.0). I also found it's very important to update PPK firmware as well - it fixed strange things for me couple of times. Simply erase it with nrfjprog and reconnect.

RE: Voltage at PPK without external supply

Stian Røed Hafskjold — Tue, 28 Jan 2020 16:25:33 GMT

And which software version are you using?

RE: Voltage at PPK without external supply

Stian Røed Hafskjold — Tue, 28 Jan 2020 16:24:32 GMT

When measuring the voltage, do you apply any load to the DUT pins, or are they floating? Which PPK revision is this?

RE: Voltage at PPK without external supply

KilianL — Tue, 28 Jan 2020 15:42:10 GMT

Hi, the PPK Software is running and the boards are separated. With or without a second usb cable on the PPK I can not apply voltage below 2,8 V. Something is back powering to the "External supply" clamps. Any other bridges that I can cut to have just the raw external voltage for my DUT?

RE: Voltage at PPK without external supply

Stian Røed Hafskjold — Tue, 28 Jan 2020 13:50:45 GMT

Hi, you need to run the PPK software at the same time as you are measuring the voltage. The PPK software is configuring the PPK correctly.

The voltage on the DK is 2.8V because of the reverse voltage protection diodes on the DK. So in DK mode, you should see 2.8V on the DUT output.

The external regulator is not working properly when the PPK is stacked on top of the DK. Use it in standalone mode as you are showing in your first picture. This setup should work properly once you start the PPK software.

RE: Voltage at PPK without external supply

Mishka — Mon, 27 Jan 2020 23:29:51 GMT

Same issue here. PPK is configured for external supply / external DUT, nothing connected. At the same time I observe 2.04V on external supply port, and 2.25V on the DUT port. What might causing it?