Electronic – How to avoid UART chip power consumption

esp32

I am using ESP32 DevKit Wroom – which is on NodeMCU. I am running this on a battery power. and if I attache USB or 9 volt supply (battery) on the VIn (i.e. 5V), the board consumes aprox ~20 mA even in deep sleep mode.

If I supply voltage 3.5 (Through the liIron battery) on pin 3.3, it will certainly bypass the voltage regulator.

Other than this Voltage Regulator, there is UART chip which is equally power hungry.

My question here is, IF i supply 3.3 Volt using on-boarded pin, will it stop current going to UART? Do we have devkit PCB diagram that can explain this?

Also with all this, will my NodeMCU with ESP32 really run on few UAmp as described in ESP32 datasheet?

Best Answer

I agree with all above comments, and will be moving soon to the bare chip in production. But before that, with NodeMCU ESP32 in hand, We have removed UART chip and 3.3 V Linear regulator.

Before doing this,

  1. Added OTA code to the ESP32 just in case required updates in future.
  2. Added external Non-Linear Voltage regulator buck after power supply and set the voltage to aprox 3.7V

Now the entire circuit can last more than 100 days with my specific use case where ESP32 walk-up daily for 100+ times, performs some operations for say 30 secs without Wifi and go to deep sleep. Also it connects to the Wifi once a day for 40 sec.

To answer my original question:

  1. Yes, if we provide regulated 3.3 on NodeMCU pin, UART will still show the consumption.
  2. Even 3.3 V Linear regulator on board also shows voltage on its output(Dont know why)

Meaning, if we are dealing with NodeMCU based ESP32, then these both the chips will keep consuming power even after supplying 3.3 V on pin.

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