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I’m working on a project were I need to power to some 24V 4-20mA sensors, a 3.3V ESP32 and a 5V SIM808 module.

To accomplish this I’m using a step-down buck converter to reduce a 12V electrolytic battery to 5V and with an LM1117-3.3 feed the ESP32, then I use a step-up buck converter to feed the 4-20mA sensor.

My issue is feeding the 5V SIM808. I tried hooking it up just in the input of the LM1117 but the issue is that when the battery discharges a bit the 5V drops and the module turns off. I thought on adding a LM1117-5.0 that allows an input from 5-12V but since this is battery powered I wanted to see if there is a more energy efficient way.

Any help would be appreciated. Thanks!

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    \$\begingroup\$ No schematic = no help. No list of technical requirements = no help. \$\endgroup\$ – Andy aka Jun 19 at 8:45
  • \$\begingroup\$ Does this happen when all three (sensors, ESP, SIM) are connected ? Have you tried testing with just the buck converter and SIM module ? The sensors or ESP may be drawing too much current from the step-down converter. \$\endgroup\$ – AJN Jun 19 at 13:32
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    \$\begingroup\$ Please write a specific question, you'll get better answers and the question will not be closed. \$\endgroup\$ – Voltage Spike Jun 19 at 15:12

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