Disabling LD5 to Decrease Power Consumption

RE: Disabling LD5 to Decrease Power Consumption

Simonr — Fri, 10 Sep 2021 11:47:55 GMT

Have you read and done the necessary steps described in Preparing the development kit (section 6.7.1) in the DK user guide? If powered by the external power supply you should short solder bridge SB12 to avoid the voltage drop as well while measuring current. Cutting SB29 will indeed just disable the power for the interface MCU, and will only allow for the board to be powered by the External supply (P21).

Yes, the external supply pins will power the whole board, but the measurement pins will only measure the current drawn from the nRF52832.

Best regards,

Simon

RE: Disabling LD5 to Decrease Power Consumption

Burnie Barren — Fri, 10 Sep 2021 11:00:16 GMT

My problem is resolved in this ticket.

RE: Disabling LD5 to Decrease Power Consumption

Burnie Barren — Thu, 09 Sep 2021 11:40:57 GMT

I made some modifications and managed to decrease the current going into the chip to 0.1 mA but when I open SB29, the chip does not function. I thought it just cuts the power to the interface MCU and interface MCU is just responsible for debugging the chip and after restart, code runs from the chip itself. Is this behaviour normal or which part am I missing?

RE: Disabling LD5 to Decrease Power Consumption

Burnie Barren — Wed, 08 Sep 2021 12:10:43 GMT

Yes I cut SB9, there I connected the multimeter. I actually just wish to activate the chip rather than the whole board, but I cannot see any direct power supply to the chip and thought 'external supply' pins do actually power up the whole board. Isn't it the case?

RE: Disabling LD5 to Decrease Power Consumption

Simonr — Wed, 08 Sep 2021 11:58:29 GMT

Please note that when you measure on the current measurement pins the SB9 should be cut in order to measure the correct power from the onboard nRF52832. See the Measuring current section of the DK user guide if you haven't already. Are you planning on running the entire Development Kit off a piezo harvesting circuit, that does seem somewhat optimistic, as the interface MCU with a debugger among other things isn't really suited for low power applications.

Best regards,

Simon

RE: Disabling LD5 to Decrease Power Consumption

Burnie Barren — Tue, 07 Sep 2021 14:04:55 GMT

Hello Simon,

Thank you for your reply. Yes, I am using the current measurements pins and I use a multimeter to do the measurement.

[quote userid="75734" url="~/f/nordic-q-a/79314/disabling-ld5-to-decrease-power-consumption/328410#328410"](turn the device off completely before removing the power source entirely before turning it back on)[/quote]

Thank you, I believe I must have done this in one of my trials but will give an explicit try.

I am running ble_app_beacon demo from SDK 17.0.2. I added the code for activating dc/dc regulator and it actually decreased the current to 0.68 mA. That is good news, however from the supply around 2 mA was still drawn. I am planning to excite this board with a piezo harvester so I believe instead of the current drawn by SoC solely, I should be more concerned about the current supplied by the external source, right?

I am open for any suggestions to decrease the power consumption.

Best wishes,

Burnie Barren

RE: Disabling LD5 to Decrease Power Consumption

Simonr — Tue, 07 Sep 2021 13:15:44 GMT

Sorry about the late reply, but I've been out of office the last few days.

LED5 on the nRF52DKs will not have any effect of the measured current when using the nRF current measurement pins on the DK (which I assume you're using) as these pins will only measure the current drawn by the nRF52 SoC on the board, while the LED5 is connected to the Interface MCU (next to the LED5).

It could still be that the device is in debug mode, as you'll need to power cycle the board (turn the device off completely before removing the power source entirely before turning it back on). Can you also provide some details as to how you measure the current consumption on your board? Are you using one of our Power Profiler Kits? And what is your application is your DK running?

Best regards,

Simon

RE: Disabling LD5 to Decrease Power Consumption

Burnie Barren — Mon, 06 Sep 2021 08:09:57 GMT

I disconnected SB29 to bypass power supplied to the interface MCU, that eliminated LD5. However, my current consumed is still 1.2 mA.