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Temporary pull-up during boot (ESP-01) (self.askelectronics)

submitted 11 months ago by ByteJunk to c/[email protected]

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Hi everyone!

I'm trying to control a "dumb" led light strip segment with an ESP-01S. This is fairly low current, the strip will pull 150mA-200mA max (depends on... artistic? needs).

I have two NPN transistors (2N2222), one to control the 12V supply to the white "channel" and the other the red+blue (don't need the green).

I had to pull-down the gates as I had some flickering, and it works perfectly if I manually connect the GPIOs after the ESP-01S boots.

The ESP will boot if I have the RX pin (GPIO03) pulled down on boot, but not if I pull down any of the others.

I'm not smart enough to come up with a way to have that extra pin I need to be high only during boot, while the gate it's attached to needs to be pulled down...

Any thought, other than getting something with more IO pins?

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[–] [email protected] 2 points 11 months ago

The 7333A is a linear regulator, which means it drops voltage by converting power to heat. Typically those make sense when the input voltage is close to the output voltage or the load is very small. If it’s getting too hot, the load is high enough that the efficiency will be very bad…whether or not this is a problem depends on your application.

Some random site claims 170mA and another claims up to 400mA. 170mA * 8.7V (12V in minus 3.3V out) = about 1.5 watts, which is too much for a TO-92 package.

Can you use a tiny buck converter instead? Or a larger package for the linear regulator that can add a small heat sink?

As for your actual circuit, the second transistor is an interesting idea (you’re using it to invert the state so you can have the GPIO pulled in the non-problematic direction?) and I don’t have enough experience to give further suggestions.