Current consumption on flash erase/write and timing

[rgrr2]

Hello

I'm looking for some information about flash erase/write currents for the nRF52840.

Somewhere here in the forum there where values mentioned about 4mA for flash erase/write of the nRF52832.  Also in this posting it was said that timing should be around minimum specified time (ms range for page erase).

My own measurements show that for the nRF52840 page erase time is around maximum at room temperature.  So what current can I assume?

Note that our application is sensitive concerning peak currents.  Allowed average current is around 1mA.

Thanks

Hardy

[cbd]

Section 5.2.1.3 of the datasheet shows a maximum 6.3mA with an active CPU, external clock, internal flash access and no DC/DC regulator or 3.1mA with DC/DC regulator and internal oscillator.

This is obviously more than your 1mA budget (if it is a total).

[rgrr2]

You are right with that.  Fortunately one can send the MCU to sleep most of the time.  There is even some spare current for BLE operation ;-)

Believe me: the device is working with the 1mA.  The questions regarding flash erase current is just fine-tuning.

[cbd]

If you're running on a very small battery, especially a non-lithium based one, just be aware that the peak current draw by the BLE may dip the voltage supply voltage below the chip reset level earlier than you expect. I've seen this happen with batteries that had a no load voltage of 2.7V

[rgrr2]

No, we are not running from battery.  We have a power source with almost constant 1mA which is buffered by a load of capacitors.

[Kenneth]

Hi,

In terms of timing to erase or write, you should calculate based on the worst case numbers, so if you need 1mA on average I suspect you will need rather large caps to handle approx. ~4mA for ~90ms, and stay idle for approx ~270ms  before that.

Best regards,
Kenneth