nRF52832 current consumption without customer applicative FW (freshly produced chipsets)

[cedric]

Hi,

I got a question on nRF52832 platform. When it is brand new (so without loading any of our FW) and powered through 3V3, it draws up to 4.6mA when powered. But we also noticed that this consumption sometimes is more (or less)

Is it because the chipset can be in different default modes when powered but not flashed?

And I guess unless we settle a specific register, so without flashing anything, we cannot use the reset (P0.21) as an actual Hw reset, am I right ? (Pulling this pin low seems to have no effect on current consumption)

I ask these specifically for Industrial test (we're ramping up), in which we do perform current measurement (All MCUs in reset) to first check there's no shortcut or abnormal soldering

It appears that pulling P0.21 down doesn't have any effect on current (which makes sense), but we 'd like to know what is the range of current consumption when this chipset is powered and unflashed

Thanks in advance for your support

Regards,

Cédric

[Turbo J]

cedric said:

powered through 3V3, it draws up to 4.6mA when powered

Sounds about right.

Empty flash is 0xFFFFFFFF, which would trigger a fault when loaded into the PC. This will also happen during hard fault handling, triggering lockup reset.

In other words, the chip is held mostly in reset, thus there will be minimal differenc in current when reset pin is actually pulled down.

There is no specified current in the PS, but an upper bound would be the "CPU running from flash, LDO" numbers.

In practise the current is significantly lower, since most of the time the CPU core will be powered but not actually running.

Note: There is AFAIK no specified timing for the lockup reset, but one could reasonably assume it takes about the same as the ~3µs typical IDLE-to-ON time.

[cedric]

Hi Turbo,

Thanks for your reply

Indeed once our app is loaded, we consume less than 1µA when powered and not running (I believe around the expected 500nA)

However, our concern was for production, where prior to flash our processors, we pull their nresets low to freeze the MCUs state and get a fixed and known current consumption (aim is to detect shortcut prior to start any flashing or functional test)

That is fine, we'll enlarge LSL and USL at factory to make sure we get no unentional failure. I just wanted to make sure that 4.6mA were typical when getting new (not loaded with our firmware) chipsets.

By the way, I couldn't find the "CPU running from flash, LDO" data in nRF52832_PS_v1.4.pdf, but that is fine

Thanks a lot for your support

Regards,

Cédric

 

[Turbo J]

Nrf52832 PS chapter 7.2.1 "CPU performance".

[cedric]

Thank you I had missed that part

Cédric