nRF9160 DK v0.8.2 current measurement & external supply

[wne]

Hi,

I'm trying to measure the current of my nRF9160 DK (PCA10090 v0.8.2) and have some problems.
In respect to the following thread (https://devzone.nordicsemi.com/f/nordic-q-a/42387/instructions-for-setting-up-9160-dk-for-current-measurement-are-confusing) I cut the SB44. Then I connected an ammeter to the pins 1 and 2. The ammeter shows constantly 0 uA/mA and the DK doesn't reach the applications start (main()).
Instead LED 1 and LED 2 are blinking very slow. By shorten the pins 1 and 2, everythings works fine again.
Did I miss to cut or short another solder bridge?

And a second question:
The board is supplied by a USB cable yet but in order to measure the current in another way I wanted to ask
if it is enough to switch SW10 to "ext" to power the DK by an external supply or if I have to handle some
solder bridges too?

The guides and existing threads are a little bit confusing in that cases...

Best regards.

[Martin Lesund]

Hi wne,

Have you tested your ammeter with something else that you can confirm it works correctly?

Please share a photo of your setup.

What application are you running on the DK?

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(for external supply you should not need to do anything other than what is posted in the thread)

You should only need to follow what Bjørn suggests:

You will need to cut the SB44 on the nRF91DK. This will disable switch U25 & therefore it does not matter which position SW10 is in.

"Measuring current using the DK guide setup will give bad results. The switch (U25) leaks current from VOUT to GND even when off.

Pin closest to USB connector is pin3
1. Measure current using an ammeter: Connect to pins 1 and 2
2. Measure current using a supply like Agilent 6705: Connect to pins 1 and 3.
3. Accidentally shorting pins 2 and 3 -> dead DK! So be careful, remove USB power before connecting your measurement probes.

To make the board work again using USB power only, short pins 1 and 2."

Summary:

Flash the secure boot & the app to the nRF91 via usb, remove the usb cable, then cut the SB44 & power the board via a PSU on connector P24. SW10 can be in either position (it makes no difference when SB44 is cut). To restore normal kit operations (e.g. erasing & programming the SiP), put a jumper on the two uppermost pins of P24.