What should VDD level be on unprogrammed device?

RE: What should VDD level be on unprogrammed device?

Kazi Afroza Sultana — Wed, 04 May 2022 04:01:43 GMT

Hi Scott,

Seems like your problem is solved. You can verify your own comment so the case can be closed.

Thanks.

Best Regards,

Kazi Afroza Sultana

RE: What should VDD level be on unprogrammed device?

ScottBBBB — Fri, 29 Apr 2022 18:42:45 GMT

We appear to have figured out what is going on. We are using a nRF52840-based module from Fanstel, and I had erroneously assumed that there was sufficient bypass capacitance internal to the module to meet the Nordic spec, but it turns out that we needed to add 4.7 uF onto VDD. Prior to that, VDD had a ton of ripple on it, but now it's a steady 1.8 V as expected.

Scott

RE: What should VDD level be on unprogrammed device?

Kazi Afroza Sultana — Fri, 29 Apr 2022 13:10:56 GMT

Hello Scott,

Could you Please send your schematic diagram? It should be like this according to your description.

You can check with our reference design https://infocenter.nordicsemi.com/topic/ps_nrf52840/ref_circuitry.html?cp=4_0_0_6_2 as well.

Thanks.

Best Regards,

Kazi Afroza Sultana

RE: What should VDD level be on unprogrammed device?

ScottBBBB — Thu, 28 Apr 2022 14:52:48 GMT

Hello Kazi,

I'm afraid that this doesn't fully address our question, though -- the parts are not yet programmed, so we have not set any registers, and we are so far not able to program the parts. We can read registers, but have not been able to write to flash nor run code. We are thus trying to figure out what's wrong, and one of the questions is whether or not we are doing something wrong with how power is supplied. I saw the 1.8 V default setting in the datasheet, but as I noted we are not seeing 1.8 V, but rather a range of higher voltages.

Regards,

Scott

RE: What should VDD level be on unprogrammed device?

Kazi Afroza Sultana — Thu, 28 Apr 2022 13:24:05 GMT

Hello Scott,

For normal operating voltage, VDD should be in the range of 1.7 to 3.6 V https://infocenter.nordicsemi.com/topic/ps_nrf52840/power.html?cp=4_0_0_4_2_7#unique_706563143 . For high voltage mode, it should be 1.8 V if you have not changed the value of REGOUT0 (default value is 1.8V).

https://infocenter.nordicsemi.com/topic/ps_nrf52840/uicr.html?cp=4_0_0_3_4_0_7#register.REGOUT0

You can check the above mentioned links to know about electrical specification and registers used for high voltage mode.

Thanks.

Best Regards,

Kazi Afroza Sultana