Low Power Argon Design with TINY85


#21

True… but since the intent of the B-Series in this project is be in an un-powered state 99.x % of the time, what about just powering via Vbus (recommended input voltage range is between 4.35V to 5.5V DC) ?

In that scenario, the ATTiny would switch a Regulator instead of the the EN Pin.
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That leaves the door open for many different possibilities in battery chemistry and pack arrangements.

But it still boils down to designing/finding a replacement for the TPL5110 and 5111 with a sleep interval longer than 2 hours…the rest seems fairly easy.


#22

The “Absolute maximum ratings” just tells you that you (probably) don’t have to power VCC, but you should pay attention to the recommended voltages:

This doesn’t begin to explain why powering this pin from a Li+ connection is acceptable since they tend to be in the range of 3.2-4.2V during operation, but as usual the documentation is inconsistent or leaves out useful design information or commentary.


#23

That’s a thought, I could use 3 Energizer L91 in series to give me 4.5V but only 3.5Ah…


#24

Waking in manual mode to increase a counter and go back under every two hours, is unlikely to cost a lot of power. I bet all the 2 hour wake-sleep cycles power consumption over say 3 years combined, would not amount to many ms of establishing a 2G connection and keeping it going. Could be worth a check for the simpler TPL5111 setup.


#25

I tried that…retained memory doesn’t survive a Power Loss (EN Pin).
That would work if ya have an easy way to store the count externally.
You are correct, the power consumed during a quick wake in manual mode is extremely tiny.


#26

The EN pin is the best alternative for getting the lowest power consumption on the Boron at this time.

Instead of using a Tiny85, I use a NL17SZ74 flip-flop and a MCP79410 real-time clock.

With that, powering this circuitry gets the sleep current down to 75 uA. However, that is still higher than it should be, because there’s a weak 100K pull-up on the EN line, and you have to counteract that all of the time when powered down by EN.

Since there is no regulator or PMIC on the B Series SoM at all, you have complete control over the power supply design you can do whatever you want. I have a sample that uses a high side load switch coming off the LiPo battery. Since I don’t need the actual EN line semantics on the B Series SoM it’s driven directly off the NL17SZ74 and there’s no need for the pull-up and N-MOSFET. I haven’t tested this design yet, however.


#27

Generally not recommended, but any experience with increasing a weak pull-up value to 300k or 1M on a reset or enable line?


#28

The problem is that the pull-up is on the Boron itself. They’re so small (0201) they’re such a pain to rework I didn’t even check to see if it’s under the shield in the bottom or not.

As for the design itself, 100K is about as high as you can go reliably.


#29

Thank you so much for your contribution to the thread @rickkas7 :+1:t3:

Do you have any insight into the best way of powering the B-series using Li-SOCl2 batteries rather than LiPo… does it really need to handle 2A currents?

Also, any update on NB-IoT in the UK with Voda?