ESP8266 Community Forum

- Sun Nov 11, 2018 8:58 am #79088 I use a surface mount 68uF 10v tantalum cap on the output of the regulators. I use that because it is the same height of the ESP-12 modules, and because of availability. It is s part we use on some products at work.

Using CMOS construction, the quiescent current
consumed by the MCP1825/MCP1825S is typically
less than 120 µA over the entire input voltage range,
making it attractive for portable computing applications
that demand high output current. The MCP1825
versions have a Shutdown (SHDN) pin. When shut
down, the quiescent current is reduced to less than
0.1 µA

If you are not using the shutdown function (the three pin package) then the quiescent current is a lot higher than some other parts. II'm sure that the Low Dropout Voltage: 210 mV Typical at 500 mA is a big factor in your choice. Designing is tradeoff and compromises.

- Sun Nov 11, 2018 1:42 pm #79089 Yes, I've choose this for the low dropout voltage and because it is the only one I can find in reasonable time for now..
I make some simulation and the difference is something 10% less battery life using mcp1825.. For the next design I'll follow your tip and try ht7833.
So you don't put a cap before the regulator?
And do you use decoupling cap on esp module?
I've read that if the battery goes to low when the esp is in deep sleep, even a charge could not wake up the module, and is necessary to Make a manual reset. Do you had the same problem?

Thank you so much
Jacopo

- Sun Nov 11, 2018 5:18 pm #79090 In my battery apps I don't bother with an input capacitor on the regulator, but I keep the lead lengths short. I do use 200uF flat smd capacitors on output.

I get good results using xc6203 regulators which have a pretty low drop out.

If you are using GPIO16 to wake from deep sleep then it is true that a low battery voltage can get the device in an unknown state and just recharging the battery will not automatically recover that without a reset. If you want to do that automatically you would need some extra support circuitry. I have also had a case where a low battery voltage has led to a corrupted SPIFFS filing system necessitating a re-format.

It is quite good to monitor the battery voltage and to notify before it gets critically low. The ADC input can be used for this as precision is not that important, although good to have a calibration factor.

- Sun Nov 11, 2018 7:31 pm #79093

If you are using GPIO16 to wake from deep sleep then it is true that a low battery voltage can get the device in an unknown state and just recharging the battery will not automatically recover that without a reset. If you want to do that automatically you would need some extra support circuitry. I have also had a case where a low battery voltage has led to a corrupted SPIFFS filing system necessitating a re-format.

Have you got some examples of time support circuit I'll need?

]It is quite good to monitor the battery voltage and to notify before it gets critically low. The ADC input can be used for this as precision is not that important, although good to have a calibration factor.

Yes, I've put this feature in my design, but just in case I don't remember to charge the battery in time