Hi everyone,
I am wondering how I can manage with different voltages from different super cap.
I explain the schematic below, I have 4 supercap (400mF rated 3.3v) that are charged by different controlers from generators. This means that at a time T1s the C1 could provide maybe 3.24V if it is fully charged or 1.24v if not, same for C2 and C3 (0 to 3.3v) and C4 between 3.2-1V. My problem is that I want to supply a low power microcontroler using the energy available on fourth capacitors.
If I connect all the capa together it means that the voltage will equalize itself, that why I put a diode after each supercap to get no current reverse from a super cap to another one. Is this schematic can work?

Thank you very much

 

Hi everyone,
I am wondering how I can manage with different voltages from different super cap.
I explain the schematic below, I have 4 supercap (400mF rated 3.3v) that are charged by different controlers from generators. This means that at a time T1s the C1 could provide maybe 3.24V if it is fully charged or 1.24v if not, same for C2 and C3 (0 to 3.3v) and C4 between 3.2-1V. My problem is that I want to supply a low power microcontroler using the energy available on fourth capacitors.
If I connect all the capa together it means that the voltage will equalize itself, that why I put a diode after each supercap to get no current reverse from a super cap to another one. Is this schematic can work?

Thank you very much
View attachment 120276

That will work fine as long as your microcontroller only needs 1 to 3.3 volts. The cap with the highest voltage will discharge first to supply power and it will be (mostly) self-balancing (not that balance is needed in your parallel setup.)

 

Thank you,
I am wondering, teh voltage after the diode will be Vcap (the highest voltage) - Vdiode?
Means I will never be able to have 3.3v?

 

Thank you,
I am wondering, teh voltage after the diode will be Vcap (the highest voltage) - Vdiode?
Means I will never be able to have 3.3v?

Right. A "standard" diode will drop 0.6V and a Schottky diode will drop 0.3V. Use a Schottky.

 

Okay thank you

 

Another question

What is the most appropriate to get a 1.5V considering that in output I need only 10uA.
Should I use a simple Voltage Regulators - Linear exemple 3.3-2 to 1.5v
or a Voltage Regulators - DC DC Switching Regulators

I think for a simple regulator I will loose lot of power just to regulate P_lost=(Uin-Uout)*Iout right?
Whereas a DC/DC will be more efficient (90%), but I need to power the IC all the time, compare to my need 10uA in output I don't know if it's worth it.

What do you think?

Thanks

 

Another question

What is the most appropriate to get a 1.5V considering that in output I need only 10uA.
Should I use a simple Voltage Regulators - Linear exemple 3.3-2 to 1.5v
or a Voltage Regulators - DC DC Switching Regulators

I think for a simple regulator I will loose lot of power just to regulate P_lost=(Uin-Uout)*Iout right?
Whereas a DC/DC will be more efficient (90%), but I need to power the IC all the time, compare to my need 10uA in output I don't know if it's worth it.

What do you think?

Thanks

Yes, if you need efficiency and long battery life, a DC/DC will be the best option. You can try to make your own from discrete parts but I think it is better to buy a module.

 

Thank you
this one should be ok
http://www.ti.com/lit/ds/symlink/tps622314-q1.pdf
or this one
http://ixapps.ixys.com/DataSheet/IXD3235_36_37.pdf