Migrating nRF52840 to nRF52833

[mtorti]

Hi,

Checking the new nRF52833, i saw that it has the same package as nRF52840.

Considering to migrate from nRF52840 to nRF52833, i checked the recommended schematics and found out the only difference is the ANT circuit.

On 52840 it has 2 caps and 1 inductor, and in 52833 it has 2 caps and 2 inductors of different values.

For the legacy products, it is acceptable to put the 52833 on the 52840 schematics (with 2 caps and 1 inductor), or the performance may be decreased a lot?

It would be interesting to direct replace the ic without making new PCBs.

[Marjeris Romero]

Hi Maximiliano,

It will depend. You will have to measure the RF TX harmonics and tune the RF matching network if needed. If you want you can send us at least 2 PCBs with the nRF52833 and we can help you with the tuning.

Best regards,

Marjeris

[chethans]

Hi,

I have similar question. Can we make NRF52833 schematic compatible with NRF52840 by adding a 0 ohm placeholder resistor at L2? Does it affect antenna performance?

We will be using a wire antenna connected via UFL connector.

Since NRF52833 is not available yet, we want to first production with NRF52840 and then move to NRF52833 without changing PCB design.

[Marjeris Romero]

Hi chethans,

Yes you can. The matching network in the reference design for 52833 will be the best alternative for your schematics, as it works best when using +8dBm as TX power for both 52833 and 52840.

Keep in mind that although the nRF52833 has the same footprint as the nRF52840, they are not "drop-in" pin compatible, so take a close look to the pin assigment for both chips when developing both hardware and software compatible for both chips.

Best regards,

Marjeris

[chethans]

Except for the ANT circuit and extra L2 for NRF52833, they are pin compatible according to the reference schematics provided. Am I missing anything else here?

[Marjeris Romero]

They are pin compatible but not "drop-in" pin compatible. In the pin assigment table for both chips you'll see that some pins are N.C. in the nRF52833 compared to the nRF52840, and also some of the IO pins names are different so they will need application-level remapping.

Best regards,

Marjeris