battery secondary power

RE: battery secondary power

RajTS — Thu, 20 Jan 2022 15:29:29 GMT

This is the circuit i am proposing.. (But don't want to do it on my dev kit). Can anyone kindly provide any inputs on this?

As I mentioned, I need the battery only when here is no power, and only to maintain the real time clock. Non-chargeable battery, so it should neither change from the power, nor discharge into it. (Hence this MOSFET where substrate is not shorted to source, and no Source-Drain diode).

Thank You

RE: battery secondary power

RajTS — Thu, 02 Dec 2021 15:41:08 GMT

MOSFET, not Transistor, you mean? Instead of the second diode.. We may not need a comparator exactly.. Or use the on-chip ADC.. Still there may be a VERY brief instance it could draw from both sources, but I believe that is better than losing power for a brief instance. I need to study about it a bit more.

Thank You

RE: battery secondary power

Jared — Thu, 02 Dec 2021 12:18:45 GMT

[quote user="RajTS"]No I can't. I can only make sure that the Ac-Dc and Battery won't leak onto one another. Not exactly make sure that battery is conserved. Hence this query..[/quote]

I see... Have you looked at using a comparator and a transistor instead of a diode? You could use the comparator to monitor the AC/DC voltage and then turn on the transistor when the voltage from the converter falls.

regards

Jared

RE: battery secondary power

RajTS — Thu, 02 Dec 2021 11:07:33 GMT

No I can't. I can only make sure that the Ac-Dc and Battery won't leak onto one another. Not exactly make sure that battery is conserved. Hence this query..

And with 52810, I don't plan to have a separate RTC chip..

Is there a proven/standard design/solution to what I am trying to do?

Thank You

Raj

RE: battery secondary power

Jared — Thu, 02 Dec 2021 08:43:12 GMT

Hi,

I can't see any reasons for this not to work for the nRF52 series. But how you make sure that the battery isn't drained during normal operation?

regards

Jared

RE: battery secondary power

RajTS — Thu, 02 Dec 2021 04:24:12 GMT

As of now, the development kit. But I may go for a custom PCB. (Already have some samples)

On other uC's, I'd just go for a diode.. as in this picture. (Not withstanding the voltage drop across the diode). But would like to try any better option.

Thanks a Lot.

RE: battery secondary power

Jared — Wed, 01 Dec 2021 12:21:26 GMT

Hi,

Are you using a custom board or a development kit?

regards

Jared