VDDHDIV5 with Normal Voltage Mode

RE: VDDHDIV5 with Normal Voltage Mode

JONATHAN LL — Tue, 14 Nov 2023 11:42:08 GMT

[quote user="SmallBee"]1. In order to ensure startup in HV mode, is it useful to delay the startup time of LDO?[/quote]

The external LDO should not have its output connected to the nRF52833 VDD pins when the nRF52833 is to run in High voltage mode.
When the nRF52833 is in High voltage mode then VDD pins on the nRF52833 is an output.

[quote user="SmallBee"]2. If it is useful, how many milliseconds should I maintain the gap in how many volts?[/quote]

It is not really recommended to supply power to VDD in this way so would not consider this useful.

Regards,
Jonathan

RE: VDDHDIV5 with Normal Voltage Mode

SmallBee — Wed, 08 Nov 2023 03:53:08 GMT

1. In order to ensure startup in HV mode, is it useful to delay the startup time of LDO?

2. If it is useful, how many milliseconds should I maintain the gap in how many volts?

RE: VDDHDIV5 with Normal Voltage Mode

Kazi Afroza Sultana — Tue, 07 Nov 2023 15:06:22 GMT

Hello,

yes, I can see from the diagram that when VBAT is not powered enough to connect VDDH the high voltage mode is turned to normal voltage mode. In our PS, it is not explicitly mentioned that ''VDDHDIV5 can not be used in norma voltage mode''. This undefined behavior works in your case does not mean we recommend doing this.

RE: VDDHDIV5 with Normal Voltage Mode

SmallBee — Wed, 01 Nov 2023 03:43:20 GMT

This is a simplified circuit

When the system boots with VUSB power
If VBAT is too low, it may cause the system to start in Normal Voltage Mode.

RE: VDDHDIV5 with Normal Voltage Mode

Kazi Afroza Sultana — Tue, 31 Oct 2023 11:37:14 GMT

Some addition to my previous comment- You can provide some examples of the measurements you are making in either case, along with the configuration you are using for the SAADC. I guess there may be some issue with the input output voltage range.

RE: VDDHDIV5 with Normal Voltage Mode

Kazi Afroza Sultana — Tue, 31 Oct 2023 09:55:35 GMT

Hello,

''I connected VDDH to the battery and VDD to LDO along with other devices''.

You are using high voltage mode. What do you mean by saying ''VDD to LDO along with other devices''. Do you mean VDD is connected to REG0?

''But the magic is if I enable VDD as input source in another ADC CH
The value of VDDHDIV5 becomes normal.'' - Plese explain this also elaborately.

Thanks.

Kazi