Help on schematics

Hello guys! I’m new in electronics, and I need some help here. I want to build a solar powered range meter with an attiny45 and a Bluetooth module, to be as power efficient as possible, I’ll use bare minimum components(no voltage regulators), working with 2.8 volts(because is the maximum voltage supported for the Vl6180x). My plan is to connect two small solar cells in parallel to charge two 3.7v batteries in series(to have a higher voltage before passing through the buck converter, in order to always maintain the input voltage higher than the output voltage, since the battery voltage drops as it’s uncharge). as I said before, the attiny45, the Vl6180x and the Bluetooth module will be working with 2.8v. My question is, this is viable, power consumption wise? I need some opinions and suggestions, please!

Anything with a buck converter (which is a voltage regulator) reduces efficiency.

There are some interesting ideas in this solar powered Arduino project.

What bluetooth module works at 2.8V? I'm used to see them needing the voltage of a LiPo battery.

For your project: use the batteries in parallel (3.7V nominal; 3.2-4.2 actual range). Use that to power your Arduino and Bluetooth. Use a breakout board like this for your sensor - very little losses on that regulator, as you use so little current for the sensor.

This is likely more power efficient overall than a buck converter, and simpler to build. I do assume the board uses an LDO regulator that still gives sufficient output voltage (even if a little lower than 2.8V) at 3.2V input.

HI,
Can you post links to specs/data of the charge controller and other hardware you are using please?

Can you please post a copy of your circuit, in CAD or a picture of a hand drawn circuit in jpg, png?

Thanks.. Tom... :slight_smile:

jremington:
Anything with a buck converter (which is a voltage regulator) reduces efficiency.

There are some interesting ideas in this solar powered Arduino project.

Hi jremington! thanks, i'll take a look at that!!

wvmarle:
What bluetooth module works at 2.8V? I'm used to see them needing the voltage of a LiPo battery.

For your project: use the batteries in parallel (3.7V nominal; 3.2-4.2 actual range). Use that to power your Arduino and Bluetooth. Use a breakout board like this for your sensor - very little losses on that regulator, as you use so little current for the sensor.

This is likely more power efficient overall than a buck converter, and simpler to build. I do assume the board uses an LDO regulator that still gives sufficient output voltage (even if a little lower than 2.8V) at 3.2V input.

Hi wvmarle! I don't know what module I'll use yet. My initial plan was to use a esp8266 module, but I read somewhere that bluetooth it's way more power efficient. I think you're right, probably the voltage regulator will be about the same efficiency as the buck converter in the end and will make all more simple. Which of this boards do you think will be more suitable to my project (more efficient)?
1 - Vl6180x
2 - Vl6180x
3 - Vl6180x

I didn't find any power consumption informations about this boards or even the datasheet of the voltage regulators, do you think it's a LDO?

TomGeorge:
HI,
Can you post links to specs/data of the charge controller and other hardware you are using please?

Can you please post a copy of your circuit, in CAD or a picture of a hand drawn circuit in jpg, png?

Thanks.. Tom... :slight_smile:

Hi Tom! this is all I have right now, I'm need you help to figuring out what components I'll use and how...

Marchi:
1 - Vl6180x
3 - Vl6180x

Here I see components that are very likely I2C level shifters,

2 - Vl6180x

here not. So board #2 would be out for me for that reason.

I didn't find any power consumption informations about this boards or even the datasheet of the voltage regulators, do you think it's a LDO?

Very likely as they're supposed to work at 3V (if I pick that correctly out of the description) but can't say for sure without knowing the part number of the regulator used.

wvmarle:
Here I see components that are very likely I2C level shifters,

here not. So board #2 would be out for me for that reason.

I didn't find any power consumption informations about this boards or even the datasheet of the voltage regulators, do you think it's a LDO?

Very likely as they're supposed to work at 3V (if I pick that correctly out of the description) but can't say for sure without knowing the part number of the regulator used.

About the 3 - Vl6180x I managed to find this page, the datasheet it's all in chinese, but the page says the it's a LDO and the dropout it's about 10mA, if I understand correctly. In the 1 - Vl6180x I could see writed in the smd 65x5, but nothing come out on a google search. I think I'll go with the 3 - Vl6180x, probably the dropout current will be even smaller than 10mA.

Dropout relates to voltage, not current. The Googloe translation of the basic specs of the SC6206 is clear enough:

High-precision output voltage: ±2%, maximum operating voltage: 6.0V;
Output voltage: 1.5 V~5.0V (step size 0.1V);
Very low quiescent bias current (Typ.=25 uA);
Strong load capacity: When Vin=4.3V and V out=3.3V, Iout= 250mA;
Very low input and output voltage difference: 0.2V at 90mA and 0.40 V at 150mA;
Good input stability: Typ . 0.03 %/V ;
Low temperature adjustment factor;
Can be used as a regulator and reference voltage;
Package form: SOT23-3

wvmarle:
Dropout relates to voltage, not current. The Googloe translation of the basic specs of the SC6206 is clear enough:

Ohh! ok, so, there is no way to know the current consumption? I mean, the efficiency...

It's all in the data sheets.
Current consumption of the sensor you can find in it's data sheet.
Add the quiescent current of the regulator as given above and you have the total current consumption.

wvmarle:
It's all in the data sheets.
Current consumption of the sensor you can find in it's data sheet.
Add the quiescent current of the regulator as given above and you have the total current consumption.

Oh! ok, I didn't knew that. Thanks so much for your help and patience to clear out my doubts...