adc: is there a way to get the VBG out of the nrf?

[Richard]

Hi,

is there a way to get the VBG reference voltage out of the nrf51822? we want to drive a very low current with it.

Thank you. Richard

[Asbjørn]

There's no way of driving anything from the VBG, but you could drive some small circuits directly from the GPIO/VDD. Would this be an option for you or do you have any voltage requirements that would make this difficult?

[Richard]

Thanks for your reply. I know the version with the GPIO/VDD (this is my current design), but in case of adc measurement this brings also a lot of trouble. So i try to use the internal VBG reference to drive a voltage divider (around 7kOhm), but it looks like there is no way to get the VBG out of the device.

I have a 1,85V power supply for my chip. So i cant't use the VDD directly for aref. But i can prescaling it internal with 1/2. Do you know how exact the prescaling is? Thanks again,..:)

[Asbjørn]

Hi, I'm not sure I understand what you are planning on doing. Could you explain a little bit more on how you plan to set this up and what you want to measure? Also, with regard to voltage dividing, you might find the blog post here useful: devzone.nordicsemi.com/.../