Voltage regulator for primary battery



  • Could you please recommend voltage regulator with 3,3V output for OEM modules powered solely by primary LiSOCl2 battery with 3,6V nominal voltage? Most important property is minimal quiescent current during deep-sleep.



  • @Eric24 As always, it's a balance between power consumtion and storage time. Chargeable batteries can source a high current, but have a higher discharge rate. For LiPo batteries it varies a lot between individual items, and is never in the range of years. If your total energy over three years fits into the capacity of the primary battery, and also the peak current is matched, than for long term operation the battery looks better.



  • @robert-hh I'm just curious what kind of "total life" you're seeing with the LiPo. It's been my experience that "very long life" products (i.e. 3+ years on a battery) can't use LiPo's because of their higher self-discharge rate (i.e. this just won't last that long, regardless of how little current the powered device needs). That may not be a factor in your application, but if you've found a LiPo with the ability to last 3+ years without recharging, I'd love to learn about it.



  • Thank you all for you replies, it is a very interesting discussion to read and learn from.

    We will use regulator from TPS630xx product range.

    Current use-case for battery powered devices is to deep sleep for most of the time and send updates (approx. 30 bytes) via raw LoRa. WiFi will be enabled only during configuration and troubleshooting. In these cases we will use external power source if the battery cannot supply required current.



  • @robert-hh
    I think these batteries have a place in applications where most time is spent in deep sleep and most of the runtime will be with WiFi off (avg consumption around 30-40mA) and occasionally send some data.

    Particularly they're a good fit if you can have WiFi off other than for very short periods and use for example LoRa or Sigfox to send data.

    If you want WiFi up and running a lot of the time then probably no.

    Lead acid, LiPos, etc all have their own set of constraints and issues so I don't see there being a single best solution for this. Definitely good to evaluate all the options - and excellent to discuss them here in forum :-)



  • @jmarcelino Looking at that datasheet and thos of other vendors it looks as if these kind of batteries and not suitbale anyhow. The ESP32 based Pyboards need 80..120 mA average current when runnig. At that consuption, according to the linked data sheet the battery voltage goes down to 2.8 V and the capacity is reduced to 2 Ah. A single 18650 LiPo accumulator performs much better.
    I made this reasoning a while ago too for an set-up required to run on battery, and after seeing the data of primary batteries, I moved to a rechargeable battery. In this case simple lead battery, since size & weight did not matter, but the temperature range should go down to -20°C at least.



  • For battery maybe check this one, it should deliver the peak current needed even without supercap:

    http://www.tadiranbat.com/assets/tl-5920.pdf (or 5920/B with a molex connector termination )



  • If you want buck/boost in a single drop-and-forget package that is more "production-ready" (SMT) than the Pololu module then the Murata LXDC2SCAAB is pretty good.

    I actually planned to use this first for my L01 board but the project "pivoted" to a different power source which is not compatible with the input range.



  • @danielm The Pololu module I mentioned is using the TPS63060 chip, similar to the TPS63025 device, but with a slightly wider input voltage range. So now you have the choice.



  • @danielm as an alternative to the LM3281, you might consider the TPS63025x. It's more expensive, but I personally like it because it's slightly more efficient and includes boost mode that may get a little more power out of a dying battery, as well as allowing you more choices of primary cell chemistry.

    But note that a single LiSoCl2 cell can typically not provide the peak current needed during radio transmission. Depending on the radio(s) and transmission duty cycle needed by your application, this can generally be solved by adding a small "super cap" in parallel with your battery. There are also hybrid batteries available (from Tadiran and ohters) that include the super cap inside the battery, but I don't see much need for those unless you have physical constraints that prevent you from adding your own cap externally.



  • The LM3281 solution based on the reference design is pretty good for most purposes?



  • @danielm I have a good experience with a Pololu S7V8A adjustable up/down regulator. It delivers its output voltage (3..8v) for an input range between 2.6 and 11.8 V, which matches nicely the 2.8 to 4.1 range of the Lithium battery. It has an shutdown input too, in which case the quiescent current is determined by the 100k pullup resistor at that input.


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