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I'm trying to design a 4G tracker that uses a 4G module and a GPS receiver. The 4G module, as the datasheet says, uses a maximum of 600mA when connected through 4G + audio working, so this is the theoretical maximum consumption the 4G module will have. The GPS I didn't choose yet but I guess it'd consume less then 200mAh.

I'm planning to communicate (through UART) with the 2 modules though an STM32L011F3UX which is ultra low power, so it'll consume very low current.

That's why I've chosen the AMS1117 with a 3.3v output, it has 1A of maximum output which I think will be enough for all the things. I didn't add the decoupling capacitors for the GPS and 4G modules yet, I'm gonna research on how I should do it.

The circuit for the AMS1117 is intended to power the STM32, 4G and GPS modules, but the decoupling capacitors on the right are for the STM32 only.

I'm mainly concerned if this power circuit is ok for these demands.

Also, the idea is to keep the 2 modules idle/in stand by for the majority of the time, like 95%! So the idea is to not waste energy. Can I trust that the AMS1117 circuit will only consume power when needed? If I need to update the location every 20 minutes, then I might need less than 150mA for the entire circuit in stand by mode for these 20 minutes, and only high consumption (possibly 800mA, let's say) for some seconds, maybe 5 seconds.

I'm grateful for any help, and I'm gonna make all these circuits and code open source.

The 4G module is a Toby-L210 https://www.u-blox.com/en/product/toby-l2-series

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    \$\begingroup\$ consume less then 200mAh. 200 mAh is not a current consumption, but rather a battery capacity. \$\endgroup\$
    – winny
    Aug 26, 2020 at 6:42

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AMS1117 has a quiescent current consumption of 5mA typical, 11mA maximum under conditions similar to yours. So that current is wasted 24/7. It is, however, a remarkably cheap regulator and thus is found everywhere. If you walk through the streets in Huaqiangbei there is a non-zero chance you might find some stuck to the bottom of your shoes.

That 5-11mA range is not a particularly low current, you can probably find a CMOS regulator that has more like 1 or 2uA of quiescent consumption. It will likely cost more.

Follow the recommendations in the datasheet as far as input and output capacitors near the regulator to the letter. And calculate the worst-case thermal conditions to ensure a reliable design. Skip either of those and you may have a very bad day.

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  • \$\begingroup\$ It's not something to be mass produced so I do not care about unit price. I've searched for CMOS regulator but couldnt find any products, just technical information on its inner workings. Can you point me to a good one? \$\endgroup\$ Aug 27, 2020 at 15:59

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