ESP8266 Community Forum

- Fri May 24, 2019 11:47 am #82462 Hello, I am starting a project that will need to consume little energy because it will be connected in lithium battery or duracell batteries.

Researching a bit about an appropriate voltage regulator I noticed that people use various models.

What has left me confused is that the vast majority use LDO regulators.

Because? Would not it be more efficient to use keyed controllers? (Bulk boost)

The features of my design are to work well with both lithium batteries that can reach up to 4.2 V and Duracell batteries (1.5 V).

What type of regulator and battery configuration should I use to achieve the longest possible operating time?

I have many doubts about this ...


Below is the list of some regulators I researched:

Regulators Ultra Low Power for ESP8266:

Normal use ESP: 50 mA a 200 mA (3 v a 3.6 v)
Deep-Sleep: 10 uA
Modem-Sleep 15 mA


MAX1724:
Range voltage: 0.91 - 5.5 V
Max current out:
Quiescent current: 1.5 uA
Drop out voltage: Step up
Indutor de 10 μH

MCP1700:
Range voltage: 6 V Max
Max current out: 250 mA
Quiescent current: 1.6 uA
Drop out voltage: 178 mV

Ht7333:
Range voltage: 12 v
Max current out: 250 mA
Quiescent current: 4 uA
Drop out voltage: 170 mV

HT7833:
Range voltage: 8 v Max
Max current out: 500 mA
Quiescent current: 4 uA
Drop out voltage: 360 - 500 mV

MCP1825:
Range voltage: 6 v Max
Max current out: 500 mA
Quiescent current: 120 - 220 uA
Drop out voltage: 210 - 350 mV

XC6203(XC6203E33):
Range voltage: 8 v Max
Max current out: 400 mA
Quiescent current: 8 uA
Drop out voltage: 300 mV

ISL91107IR:
Range voltage: 1.8 V to 5.5 V
Max current out: 2A
Quiescent current: 45 uA
Drop out voltage: Buck-Boost 96% efficiency

TPS73633:
Range voltage: 5.5 V
Max current out: 400 mA
Quiescent current: 10 mA???
Drop out voltage: 75 - 200 mV

AP2112:
Range voltage: 6 v Max
Max current out: 600 mA
Quiescent current: 55 uA
Drop out voltage: 250 mV

RT9013:
Range voltage: 5.5 v Max
Max current out: 500 mA
Quiescent current: 25 uA
Drop out voltage: 250 mV

AAT1217:
Range voltage: 6 V
Max current out: 600 mA
Quiescent current: 300 - 500 uA
Drop out voltage: stepup 93% efficiency

TLV73333:
Range voltage: 5.5 v Max
Max current out: 300 mA
Quiescent current: 34 uA
Drop out voltage: 150 mV

LM2936:
Range voltage: 5.5 V to 40 V
Max current out: 250 mA
Quiescent current: 20 uA
Drop out voltage: 400 mV

TC1262:
Range voltage: 6 V
Max current out: 500 mA
Quiescent current: 130 uA
Drop out voltage: 650 mV

SPX3819:
Range voltage: 16 V Max
Max current out: 500 mA
Quiescent current: 8 uA
Drop out voltage: 550 mV

AMS1117:
Range voltage: 12 v Max
Max current out: 1 A
Quiescent current: 5 mA
Drop out voltage: 1.3 V

- Fri May 24, 2019 11:54 am #82463 I have tried the MCP1700 with a rated output of 250mA. It was not reliable. I suggest using a part with a 500mA rating.

- Fri May 24, 2019 2:42 pm #82465 I think one of the reasons why good LDO regulators are popular for LIPO battery projects is that they are simple, cheap and pretty efficient given that the voltage drop wastage from the LIPO regulating down to 3.3V is actually pretty small.

The working range of typical LIPO batteries is from 4.2V down to 3.3V. Raw ESP modules will operate fine at 3.0V so even taking into account drop out voltage of a good LDO you can extract pretty much all of the charge from the cell.

Finding efficient switching regulators with low quiescent is quite difficult and if you add in complexity of buck / boost to run down to the lowest voltage then it gets even harder.

Having got a reasonably efficient regulator, there is more to be gained by optimising the software to spend as much time in deep sleep as possible rather than worrying about a few % in the regulator. That means using the longest sleep time consistent with functionality and minimising the wake time to perform any action. In particular, wake time can be kept low by using techniques like only turning wifi on when needed (e.g. batching up results) and by avoiding dns if possible.

It is obviously important to ensure that any other sources of quiescent current are kept low by paying attention to any biasing circuits and powering down any sensors.

Now if you want to use alkaline cells as well then the first thing to consider is in what configuration. If 1 or 2 then you have no choice but to use a boost regulator. 3 cells would give something comparable to the LIPO range 4.5V down to 3.0V with maybe a bit of charge left at the bottom end. 4 cells is swinging the argument in favour of a decent buck as the wastage through an LDO is becoming significant.

I get good results using the xc6203 in my LIPO projects. Note there are two variations of this chip. I prefer the E variant which does not have the hard current limiter built in so there is less risk with the short duration 400mA spikes the esp8266 sometimes needs (pulse current ratings are up to 600mA). Decent decoupling also helps avoid problems in this area.

- Thu May 30, 2019 7:12 am #82557

I have tried the MCP1700 with a rated output of 250mA. It was not reliable. I suggest using a part with a 500mA rating.

Thanks for the tip!
Did you use tantalum capacitor?
I saw several people using 250 mA.
I thought the supply would only be tight with 250 mA.
Thank you!