ESP8266 Community Forum

- Sun Mar 10, 2019 8:23 am #81006

hookup as in attach/power...

How are you powering the ESP8266?

I am trying to power it using a voltage divider as described in my original post.

Z1 = 1kOhm
Z2 = 2.2kOhm
Vin = 5V
Vout = 3.5V

Though I have also done a 1kOhm to 2x1KOhm to get exactly 3.3v

You get that voltage only with those two components connected. As soon as you add in an additional device (the ESP-01) the calculation no longer is valid.

You need to have a proper voltage regulator to power the ESP circuitry. It needs to provide 3.3 volts at minimum load and also at maximum load.

The circuit you showed can be used to convert a port pin level (TX from the Arduino) to the RX pin of the ESP8266. The RX pin does not load down the voltage divider that has those resistor values.

But this is not the case when it comes to powering the ESP8266. The ESP8266 can draw enough current to make it look like it was a 15 Ohm resistor. If you put a 15 Ohm resistor across the 1K resistor in your voltage divider you will not get 3.3 volts.

- Sun Mar 10, 2019 8:30 am #81007 Clearly, you don't get a voltage drop of 150V but the message is clear: you can NOT power your ESP01 like this. Your voltage divider will only produce 3v3 as long as NO current is drawn on the Vout pin.
Find a 3v3 regulator. Something like https://www.ebay.co.uk/itm/5X-AMS1117-3-3-DC-Regulator-Step-Down-Power-Supply-Module-4-75V-12V-to-3-3V-S1D5/282724628325?epid=2243978153&hash=item41d3b37765:g:jQ4AAOSw9gRaAcQ0 will do just what you want.

considering not the peak current draw of esp8266 but only average 150mA during startup, you get a calculated voltage drop on Z1 of 150V ... so no supply at all.
Passive voltage dividers are not feasable as supply for most devices with varying current draw.
You might get better results with resistor and zenerdiode.
But for esp you definitely need active voltage regulation.

- Sun Mar 10, 2019 5:54 pm #81022 So I have found the "LM1117 800-mA Low-Dropout Linear Regulator" the "MCP1702 3302E 250 mA Low Quiescent Current LDO Regulator" As well as a "Configurable DC DC Buck Converter Step-Down Module" rated at 3A.

Would all of these work? I tried the MCP1702 And it seems to power correctly, but occasionally the serial communication (from the ESP to an Arduino) has a bad line, I am uncertain if this is the cause, or if the issue is elsewhere?

- Sun Mar 10, 2019 6:41 pm #81023 The LM1117 is fine if you are using a 5 volt power source. It has too much voltage drop when used with lithium batteries.

I found the MCP1702 to be unreliable. During some peak current demands from the ESP8266 the output of the
MCP1702 can produce significant dips in the output voltage. This was a big disappointment for me because the MCP1702 has a lot of good things going for it. I had used it initially when I first started using the ESP8266. I thought I was getting sporadic software crashes because of bad code, but after changing out the regulator to a higher capacity part the crashing stopped.

The HT7333 is often used but it also has a 250mA rating. I do not consider it adequate. Less know is the HT7833 that has a 500mA rating. This is a much prefered part as far as I'm concerned. And it can be bought at a low cost. it is also available as a thru hole part and that might be important if you are not using a surface mount designed board.(hacking something together, or on a breadboard) http://www.holtek.com.tw/documents/1017 ... 99f2d0f6d7

I have used the Microchip TC1262 a lot. It is another good part but it is not as low in cost as the HT7833 or the LM1117. https://www.aliexpress.com/item/10pcs-1 ... 78069.html

Those are the linear parts that I have experience with.

I tend to use 5 volts and then a linear regulator to provide the 3.3 volts for the ESP. There is little to gain by using a switching regulator when you start with 5 volts. I have designed in a switching regulator to go from 5 volts to 3.3 volts for a Microchip PIC32 based design at work. The PIC32 is the main processor. There will be a ESP32 acting as a wifi and bluetooth connection option. This will also be powered by the same 3.3 volt switching supply. There is a cheap board being made called the Mini360 and I have had a lot of success using it to go from 12 volts to 5 volts.

The mini360 was originally based on the MPS MP2307DN but now is often made with a cloned part. I have found differences in the behaviour of the cloned part but that was in an unusual application. I think in most cases the mini360 with the cloned part will work well but we only use the original MPS part for our products.

I have designed in the MP2307DN into the product but have only made a prototype batch so we can do software development. I still am a little uncertain about using it. Hopefully I will feel more confident about it in time.