How many volts can feed esp32s

maxo96
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How many volts can feed esp32s

Postby maxo96 » Fri Aug 10, 2018 9:05 pm

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How many volts can I feed esp32s with an external source through vin

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kolban
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Re: How many volts can feed esp32s

Postby kolban » Sat Aug 11, 2018 5:12 am

If we look at the top left of the schematic diagram found here:

https://dl.espressif.com/dl/schematics/ ... 80607a.pdf

It would appear that we can supply an external source of 5V. This appears to enter a voltage regulator that drops the output to 3.3V.
Free book on ESP32 available here: https://leanpub.com/kolban-ESP32

maxo96
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Joined: Fri Aug 10, 2018 8:47 pm

Re: How many volts can feed esp32s

Postby maxo96 » Sat Aug 11, 2018 6:34 am

when connect 5v to vin oled that connected to esp32 (oled take power directly from power sorce ) oled cant start and didn't exit void setup and didn't go void loop

ESP_Sprite
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Re: How many volts can feed esp32s

Postby ESP_Sprite » Mon Aug 13, 2018 2:14 am

What generates the 5V you use and how do you connect it to the board? The ESP32 has somewhat high requirements for a power source (>=500mA) and not all power sources can deliver that.

btuzin
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Joined: Thu Jul 26, 2018 4:11 pm

Re: How many volts can feed esp32s

Postby btuzin » Tue Sep 11, 2018 6:02 pm

3 AA batteries can deliver 5.4 volts to start. Looking for longest possible battery life. My question is do we connect to 5v or 3.3v pin?

ESP_Sprite
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Re: How many volts can feed esp32s

Postby ESP_Sprite » Wed Sep 12, 2018 1:42 am

I'd say none of the above. 5.4V most certainly is too much for the ESP32 that is directly connected to the 3.3V line of the ESP32. From what I remember, boards like these usually use the AMS1117-3.3, which has a dropout voltage of 1.1V, so it needs 4.4V at minimum to regulate its output voltage. If the batteries are even slightly depleted, the board can conk out (although it may work, it's really dependent on the behaviour of the LDO on the board). If the user decides to install NiMhs, with only 3.6V the system is pretty likely to collapse.

You can try feeding it into the 5V line, but you may be better off feeding the battery voltage through a buck-converter or LDO meant to have a low dropout (the HT7833 is my personal favourite at this moment, for instance) into the 3.3V line. Maybe even use a 3.0V regulator so it has a little more headroom to work with.

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