51802 debug mode consuming less power?

[Borden]

Hi community, I'm running a 51802 on my custom board with no other parts on it, except for some buttons and leds directly connected to GPIO, and a DC/DC converter which feed the 51802 with 1.8V power directly. I'm running a custom 2.4G protocol with neither softdevices, nor Gazell lib, which keep 16M clock always running.

Now when I try to optimize power, I've found some interesting thing that I can't find an explanation. I measure current before the DC/DC, so the absolute current read is not so relevant. The cpu is running the main loop steadily merely check for GPIO buttons, not much radio activities except sending a heartbeat packet every second,

the current read 2.21mA.

But if I reset the board to debug mode(with jlink plugged),

the current read 0.96mA.

I've checked this many times to make sure, as long as power is on, the consumption keeps the low state, and there seems no difference of the functionality of the 51802.

So my question is: why in debug mode, the power consumption reduced to about 44% of the normal state? what's changed inside the chip?

[Sigurd]

Hi,

It’s actually the other way around. When you do a power-reset, the nRF51 will exit debug mode. Debug mode consumes around ~1mA, so you will see a ~1mA reduction when you resume normal mode. Please see section 11.1.3 "Resuming Normal Mode" in the nRF51 reference manual

[Borden]

I've uploaded a better video to make things more clear:video 2

In this one I turned on an LED to indicate syetem is on or off. now we can see:

1. In the first stage, when I powered it on, it's 3.86mA. then I turned it into system off mode, we read 0.02mA, so clearly the chip is in the normal mode.
2. then I triggered it into debug mode, we got about 2.80mA, after I turned it off, it read 2.32mA, that showed the chip is in debug mode.

I think this clip can make things obvious, that when my board is in debug mode, the power consumption is less than normal mode, over 1 mA, I can't understand that, I hope I can get some help here, 1mA lower power is a big temptation for me which I don't want to miss.