nRF9160 capacitors for VDD pins

RE: nRF9160 capacitors for VDD pins

Andreas — Fri, 06 Nov 2020 14:15:25 GMT

Hi,

See the compatibility matrix: https://infocenter.nordicsemi.com/topic/comp_matrix_nrf9160/COMP/nrf9160/nrf9160_ic_revision_overview.html?cp=2_0_3_0

Rev2 is indicated by 'B1' in the build code, rev1 is 'B0'. For new designs I recommend you use Rev2.

Best regards,
Andreas

RE: nRF9160 capacitors for VDD pins

bojan — Fri, 06 Nov 2020 13:28:57 GMT

[quote userid="9102" url="~/f/nordic-q-a/67991/nrf9160-capacitors-for-vdd-pins/278768#278768"]Also note that the specified current consumption is measured with these capacitors in place[/quote]

This is great to read! :-)

I see you mention Rev1 and Rev2 of nRF9160. When speaking about versions, I can see many different flavors of nRF9160 on DigiKey, for example - link (NRF9160-SICA-R, NRF9160-SICA-R7, NRF9160-SIBA-R7, NRF9160-SICA-B1A-R7, NRF9160-SIAA-B1A-R7...). Which one is the latest or the most suitable to use?

Regards,

Bojan.

RE: nRF9160 capacitors for VDD pins

Andreas — Fri, 06 Nov 2020 12:27:25 GMT

Hi Bojan,

Thingy91 and nRF9160-DK(pre v0.15) follow the reference circuit for Rev1 of nRF9160. nRF9160-DK v0.15 (and later), and the Hardware Design Guidelines follow the reference circuit for Rev2 of nRF9160. Rev2 will take over eventually, and Rev1 works better in Rev2 circuits than the other way around, therefore this recommendation.

We do not specify specific part numbers for our boards or designs, but from experience I know Murata GRM is used quite a bit. Also note that the specified current consumption is measured with these capacitors in place, you will not get worse current consumption by populating these and I doubt there is significant difference at least between parts from recognized vendors.

Best regards,
Andreas

RE: nRF9160 capacitors for VDD pins

bojan — Fri, 06 Nov 2020 10:48:04 GMT

Hello, @Andreas

Thanks for your feedback.

The official versions of Thingy:91 and nRF9160-DK schematics have 4.7uF on VDD pins and 47uF on DEC0 pin as you can see here:

Hardware Design guidelines contain the opposite info. Anyway, it makes more sense to me to design by respecting Hardware Design guidelines document. Thanks for pointing it out.

All those capacitors connected VDD pins should be low leakage from the battery point of view. It can happen very easily that more current leaks through those capacitors than through the nRF9160 and the rest of the chips in sleep mode! This will obviously have a negative impact on battery life.

In that sense, can you recommend me some low leakage capacitors that we can use? Is it generally better to use tantalum instead of ceramic?

Thanks in advance.

Sincerely,

Bojan.

RE: nRF9160 capacitors for VDD pins

Andreas — Thu, 05 Nov 2020 12:21:40 GMT

Hi,

See the nRF9160 Hardware Design Guidelines whitepaper: https://infocenter.nordicsemi.com/topic/nwp_037/WP/nwp_037/nwp_037_intro.html?cp=16_1

If your supply can provide >500mA for sufficient amount of time with a stable supply, then additional capacitors are not needed. You should make sure to add the described caps close to the pins though. Note that the current specification indicates 47µF, not 4.7µF, on VDD. As for VDD_GPIO and DEC0, any 4.7µF with similar specs can be used.

Best regards,
Andreas