nRF52811 vs nRF52832 current specs+ wake on LPCOMP?

[dbk1987]

Hi,

It seems that the nRF52811 for the most part draws less current the nRF52832.  For example:

nRF52811:   1.4 μA at 3 V in System ON mode, no RAM retention, wake on RTC

vs.

nRF52832:   1.9 μA at 3 V in System ON mode, no RAM retention, wake on RTC

Some questions:

Why does the nRF52811 draw less current?

Does Nordic make BLE IC's that draw even less current than the nRF52811 (or nRF52810)? 

Does the nRF52811 have a 'Wake on LPCOMP' feature? If so, what's the current draw? There's no mention of it on the spec sheet..

Thanks!

[Stian Røed Hafskjold]

Hi, sorry for the late reply.

The nRF52811/810 draw less current because they are smaller chips with less logic. Less tings to power up = less current. Also, they are newer than the nRF52832/840 and therefore more power optimized.

Currently then nRF52810/811 has the lowest idle currents, but the completely new nRF5340 chip has a more power optimized radio, CPU and peripherals in general, so typically the run currents and thus the total average current will be smaller.

The nRF52811 does not have the LPCOMP peripheral, and therefore not the "wake on LPCOMP feature": https://infocenter.nordicsemi.com/nav/4_3_0_5

The wake up sources for the nRF52811 in system OFF mode are GPIO and reset: https://infocenter.nordicsemi.com/topic/ps_nrf52811/power.html?cp=4_3_0_4_2_1#unique_261277599

[dbk1987]

Hi Stian,

Thanks for the reply.  Now curious about the nRF5340.. It seems like its spec sheet doesn't have the current specs populated yet.  Any sense of how much current it draws in Wake on LPCOMP sleep mode?  Also, does Nordic plan to release the chip in packages smaller than 7x7? 

[Stian Røed Hafskjold]

Hi, the engineering version of the chip was released not long, and the documentation is still in a preliminary stage. The production version is not released yet, and therefore things can change when it comes to current consumption specs.

Please contact your regional sales manager with questions about timeline and planned features (chip packages), as this is confidential information at the moment.

I can try to set up an example and measure the LPCOMP in sleep mode here, but I will have to come back to you after I have the measurement setup and software up and running.

[dbk1987]

Thanks! That would be very helpful! It would also be helpful to have a sense of how much current is drawn during BLE transmissions at various gains : )  

[Stian Røed Hafskjold]

Hi, I measured the wake on LPCOMP on nRF5340 to be 0.9 µA in System OFF mode. But this might change later when tings are optimized more.

Here's a plot of an advertising event with an 11 byte payload, at 3V, measured on the nRF5340

As you can see the total charge for the event is at 6.85 µC. Comparing that to the nRF52832 (using the online power profiler) you get 10.85 µC, which is a 37% reduction.