nrf52833 standby current reaches 60uA

RE: nrf52833 standby current reaches 60uA

hmolesworth — Thu, 03 Mar 2022 01:08:15 GMT

If changing C6 doesn't affect the frequency then we must assume the nRF52833 uses a hysteretic controller with a fixed frequency and periodic charge time fixed by Vnom+-Vhyst. This fixed frequency is presumably some RC-oscillator, the details of which we do not know. The likely cause is then the RC components which are used to determine that frequency, however the very wide range reported seems improbable.

It is not clear what other components are on the board, or what power supply is used. Does the battery voltage vary with temperature? Testing a bare nRF52833 with no other components other than the required regulator C and R is probably the best step; preferably on a board where all other components are removed. Nordic could probably do this test but maybe you could test with your board. I only help out from time to time, if I get time I will try a local heat test but can't give a timescale.

Also internal leakage affects the 1.3 volt internal rail, whereas external components load Vdd; we don't know what effect that has on the hysteretic frequency.

RE: nrf52833 standby current reaches 60uA

justin0407 — Wed, 02 Mar 2022 07:41:11 GMT

Differences between the MCU version produced?I'm using the MCU of screen printing is N52833-QDAAA0-2117FX.

RE: nrf52833 standby current reaches 60uA

justin0407 — Wed, 02 Mar 2022 07:15:00 GMT

Sorry, I don't have such test equipment, can you help provide this data?

I modified the C5 and C6 respectively, but the refresh rate remains unchanged.

RE: nrf52833 standby current reaches 60uA

hmolesworth — Wed, 02 Mar 2022 03:21:52 GMT

Did you increase C6? C6 should affect the refresh rate.

.. and did you test this:

"the internal leakage of the nRF52833 rises with temperature, and there is no control over this but it can be measured by testing an isolated part, crudely put swiftly heat the package of the nRF52833 alone to 100 degrees while not heating the rest of the board and components"

RE: nrf52833 standby current reaches 60uA

justin0407 — Wed, 02 Mar 2022 02:01:28 GMT

I try to increase the capacitance value, but has no effect on refresh rate and.

Refresh rate should only be affected by the MCU internal capacitance?

Under the environment of 100 degrees Celsius, standby power consumption is short of 15 ua manual, actual it is around 60 ua.

RE: nrf52833 standby current reaches 60uA

hmolesworth — Tue, 01 Mar 2022 16:17:07 GMT

The 4.7uF or higher regulator capacitors are the key, these should be temperature stable and ceramic. Here are 3 example charts, select the expected variation (these are worst-case).

X5R

X7R

X7S

A sample data sheet is shown here avx. Typical manufacturers are Murata and Kyocera. Remember ceramic capacitance should be de-rated 50% from the required value, so a 3.3 volt output requires a 6.3 volt or higher capacitor.

RE: nrf52833 standby current reaches 60uA

justin0407 — Tue, 01 Mar 2022 03:43:00 GMT

Hi hmolesworth,

Refresh the frequency with which a capacitor?Should use what kind of material of capacitor?As shown in figure.

Regards,

Justin

RE: nrf52833 standby current reaches 60uA

hmolesworth — Mon, 28 Feb 2022 16:12:24 GMT

The refresh frequency is directly related to the reservoir/smoothing capacitance fitted to the regulator output. Assuming ceramic capacitors, the capacitance already should be derated 50% from the required value, so a 3.3 volt output requires a 6.3 volt capacitor.

With increase in temperature, the capacitance further decreases (by as much as 30% depending on capacitor type). A 30% decrease in DC-DC capacitance would result in an increase in frequency by a similar amount as the refresh tries to maintain a fixed mean voltage with a faster decaying capacitor voltage, which likely explains the figures you are seeing. There are capacitors which would have better temperature performance, or alternatively choose a larger capacitance value. Tantalum capacitors are entirely unsuitable in this application due to very high leakage. Also the internal leakage of the nRF52833 rises with temperature, and there is no control over this but it can be measured by testing an isolated part, crudely put swiftly heat the package of the nRF52833 alone to 100 degrees while not heating the rest of the board and components.

RE: nrf52833 standby current reaches 60uA

Sigurd Hellesvik — Mon, 28 Feb 2022 15:17:44 GMT

There are no special configurations needed for 105 degrees Celcius.
For all temperatures and the nRF52833, here are the things you ask for:

Reference circuitry

SDK: You can choose between nRF Connect SDK and the nRF 5 SDK, but I recommend to use the nRF Connect SDK v1.9.0 at this time, as it is the newest.

Current consumption

Regards,
Sigurd Hellesvik

RE: nrf52833 standby current reaches 60uA

justin0407 — Mon, 28 Feb 2022 09:15:21 GMT

Hi Sigurd Hellesvik,

I have been trying to change from DC/DC mode to LDO mode, but it looks more standby current.

Please provide reference circuit diagram of 105 degrees Celsius environment, current data set, the SDK version, software, etc.

Regards,

Justin

RE: nrf52833 standby current reaches 60uA

Sigurd Hellesvik — Tue, 22 Feb 2022 13:31:04 GMT

From the spec:

"Auto-controlled refresh modes for LDO and DC/DC regulators to maximize efficiency"

You are not able to control the refresh modes, as they are automatically controlled by the chip.

However, you could try to change from DC/DC mode to LDO mode, and see if you like this consumption better?

Regards,
Sigurd Hellesvik

RE: nrf52833 standby current reaches 60uA

justin0407 — Tue, 22 Feb 2022 09:52:41 GMT

Hi Sigurd Hellesvik,

I found that in 100 degrees Celsius environment faster refresh mode frequency, leading to reach 60 ua standby current.

Tests found that under the room tempreature of the refresh rate about 16 hz, 100 degrees Celsius environment about 120 hz refresh rate.

In 100 degrees Celsius environment, refresh model of half cycle of about 100 ua peak current, the second half of the cycle of current about 15 ua, so the average current of about 60 ua.

I think close to refresh the model to solve the problem, but I don't know how to close the refresh mode.(nRF52833 is working in dc-dc mode.)

Regards

Justin

RE: nrf52833 standby current reaches 60uA

Sigurd Hellesvik — Tue, 22 Feb 2022 07:54:28 GMT

[quote user="justin0407"]First, about 2uA standby current in room temperature.[/quote]

2uA standby in room temperature seems to be normal for idle current, see our online power profiler.
60uA is higher than I expect.

Check your other components for 100 degrees celcius. Maybe the other components are the reason for the current consumption?

[quote user="Sigurd Hellesvik"]As far as I know, no special hardware or software is needed for operating the nRF52840 in 100 degrees. [/quote]

Sorry, I typed a wrong number.
As far as I know, no special hardware or software is needed for operating the nRF52833 in 100 degrees celcius.

[quote user="justin0407"]Third, Change the way, why there will be a current pulse in this picture when standby?About 16 hz frequency and frequency varies with the change of environmental temperature changes.[/quote]

The spikes is explained in this post. They are because of refresh mode.

Regards
Sigurd Hellesvik

RE: nrf52833 standby current reaches 60uA

justin0407 — Tue, 22 Feb 2022 01:47:55 GMT

First, about 2uA standby current in room temperature.

Second, I'm using the nRF52833, can you tell me is the difference between nRF52833 and nRF52840 in 100 degrees Celsius environment?

Third, Change the way, why there will be a current pulse in this picture when standby?About 16 hz frequency and frequency varies with the change of environmental temperature changes.

RE: nrf52833 standby current reaches 60uA

Sigurd Hellesvik — Mon, 21 Feb 2022 12:55:38 GMT

Hi Justin

[quote user=""]First, NRF52833 work environment at 100 degrees celsius, standby current reaches 60uA.[/quote]

See Electrical Specifications on Sleep for expected current consumption based on temperature.
What is your standby current in room temperature?

[quote user=""]Second, When the NRF52833 working in 100 degrees Celsius, what kind of processing software or hardware needs to be done.[/quote]

As far as I know, no special hardware or software is needed for operating the nRF52840 in 100 degrees.

[quote user=""]Third, When the NRF52833 dormant, how to shielding the red signal in the frame?[/quote]

I do not think I understand what you mean by "shielding". Can you say question in another way?

Regards,
Sigurd Hellesvik