ADP2291 Battery Charger Circuit

Thread Starter

turgut

Joined Nov 4, 2022
19
Hello everyone!
Im designing a battery charger circuit with ADP2291. You can see the datasheet in this link.
https://www.analog.com/media/en/technical-documentation/data-sheets/ADP2291.pdf
Normally this circuit should work like this. When you choose RS=200mohm you have to get Imax=750mA (Changing between Vin=4.5-12V). And when you choose RS=100mohm you have to get Imax=1.5A.(Changing between Vin=4.5-12V)

Here are my inputs,
-Vin=5V Radj=open Vrs=70-100-130mV RS=100mohm&200mohm (i tried different ways)
-My battery voltage between 3-4.2V. Not less than 3V and not equal or higher than 4.2V. (I also tried the battery for is it healthy.)

My outputs like this,
-Vadj=3V Vout=4.2V (stabile)
-Icircuit= 243mA and Ibat=230mA

I exactly set the figure.23 and figure.24 from datasheet. I also tried lots of different way. But I couldnt find the answer. Can anyone help me about ADP2291 or why its not working healthy?
 

Ya’akov

Joined Jan 27, 2019
6,853
Welcome to AAC.

The first thing I would check is that your sense resistors are the right values. A 100mΩ is a very small value. Depending on where you got the resistors from they could be out of spec.

Beyond that, without photos of the actual connections, if I take you at your word that you’ve connected everything properly, there is just not enough information to be able to tell what might be wrong.
 

Thread Starter

turgut

Joined Nov 4, 2022
19
So the transistor types and resistors values are all exactly as shown in the datasheet?
What do you consider "healthy"?
Transistor type is FZT549 like in the table in the datasheet but im not sure about resistors. I tried to check resistors but multimeter is not enough for mOhms.
 

Thread Starter

turgut

Joined Nov 4, 2022
19
Welcome to AAC.

The first thing I would check is that your sense resistors are the right values. A 100mΩ is a very small value. Depending on where you got the resistors from they could be out of spec.

Beyond that, without photos of the actual connections, if I take you at your word that you’ve connected everything properly, there is just not enough information to be able to tell what might be wrong.
Im not sure about resistors. I tried to check them but my multimeter is not measuring mOhms.
 

KeithWalker

Joined Jul 10, 2017
2,604
Im not sure about resistors. I tried to check them but my multimeter is not measuring mOhms.
Multimeters are not ideal for measuring low value resistors because of test lead and connector resistance. A better approach is by putting your sense resistor in series with a known good resistor with a higher value, applying a known voltage across them both and measuring the voltage across the sense resistor. That way, the lead resistance as negligible effect on the accuracy of the measurement.
 

Thread Starter

turgut

Joined Nov 4, 2022
19
Hello everyone!
Im designing a battery charger circuit with ADP2291. You can see the datasheet in this link.
https://www.analog.com/media/en/technical-documentation/data-sheets/ADP2291.pdf
Normally this circuit should work like this. When you choose RS=200mohm you have to get Imax=750mA (Changing between Vin=4.5-12V). And when you choose RS=100mohm you have to get Imax=1.5A.(Changing between Vin=4.5-12V)

Here are my inputs,
-Vin=5V Radj=open Vrs=70-100-130mV RS=100mohm&200mohm (i tried different ways)
-My battery voltage between 3-4.2V. Not less than 3V and not equal or higher than 4.2V. (I also tried the battery for is it healthy.)

My outputs like this,
-Vadj=3V Vout=4.2V (stabile)
-Icircuit= 243mA and Ibat=230mA

I exactly set the figure.23 and figure.24 from datasheet. I also tried lots of different way. But I couldnt find the answer. Can anyone help me about ADP2291 or why its not working healthy?

Im adding the schematic. It is not working as expected
 

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Thread Starter

turgut

Joined Nov 4, 2022
19
hi tur,
Please describe how it is not working.?
E
Normally this circuit should work like this. When you choose RS=100mohm you have to get Imax=1.5A.(Changing between Vin=4.5-6V)
When Im setting Vin as 5V, RS=100mohm and Radj=open, Im getting Vadj=3V, Vout=4.2V; VRS=70mV (have to 150mV), Imax=240mA (have to 1.5A). Imax and VRS is not working as expected
 

Thread Starter

turgut

Joined Nov 4, 2022
19
I have better and new results. First I changed FZT549 with a new one. Also Im not using 2N7002 as MOSFET now. I changed 2N7002 with IRFZ44N for testing because sometimes 2N7002's foot is getting damage. I set figure.24 (charge termination) again with this components. New results like that,
-Vin=5V Ibat=130mA
-Vin=6V Ibat=260mA
-Vin=7V Ibat=395mA
-Vin=8V Ibat= 516mA
Now I can getting higher currents. But FZT549 is over heating when voltage increase 6V. Also its not charging battery as it should be. 12-13mV charging per 10 minutes.
 

Thread Starter

turgut

Joined Nov 4, 2022
19
hi tur,
Check the d/s for over heating indication, do you have a heat sink on the FZT.?
E
View attachment 280255
I think I find the problem. Still i want to ask am i thinking right? FZT549 and FZT749 both of max power is 2W. Im getting 400mA when Im giving 5v. That means 2W-max value for the transistors. They cant get higher miliAmps because they are in maximum power.
My idea is if i change the transistors with higher watts it should work. I need 750mA-800mA when Vin=5V so if i choose 3-4W transistor my circuit will work as expected.
 

ericgibbs

Joined Jan 29, 2010
16,748
hi tur,
The ADP2291 d/s states a Base drive capability of 40mA.
So if you want say 800mA, the power transistor must have an HFE of 800mA/40mA = 20 for that IC current
The FZT549 should be able to handle that OK.

The transistor dissipation is the voltage across the transistor times the current through the transistor.

So assume that the battery is at say 4V, and you are using a 10V source voltage thats 6V across the transistor at 0.8A == 4.8Watts

The transistor rated at only 2Watts in air, so say a 4V battery voltage and a 6V supply ie: 2V across the transistor at 0.8A =1.6Watts.

E
Update:
Image #2, text confirms the V supply limitation.
 

Attachments

Last edited:

Thread Starter

turgut

Joined Nov 4, 2022
19
I said I set completely the figure-22 and the figure-23 in the datasheet. The circuits are not working as expected. This part is important "The circuits are working but not as expected."

In addition i find a list in a web site which i added the link. This list is telling that which products' examples are false and which products' examples are true. According to the list the examples are false which has ADP2291. So i will add link and photos about ADP2291. Im waiting different ideas, examples or true components which i can use. Also i wonder is this component working healty or the component has a problem?

If i choose different transistors such as ZXT790AKTC, BDP954H6327XTSA1 and DXTP3C60PS-13 circuit can work? Because FZT549-FZT749 are really heating even if has heatsink.
Also im going to change resistors with different values such as 50, 100, 200, 300 milliOhms or maybe little higher.
Are there useful or not? Its my first project and its getting complicated.
Im completely open any different suggestions.


A photo is from my circuit and a photo from the list.

https://ez.analog.com/cfs-file/__ke...ments/00-605-00-00-00-05-94-80/attachment.pdf

thumbnail_Screenshot_2022-11-08-11-03-10-879.jpg

ADP2291-ADEngineerZone.png
 

Thread Starter

turgut

Joined Nov 4, 2022
19
Hello im sending the last measurments if you can see a different thing which i cant. Im trying lots of thing but anything is not working.
FZT549-IRF4905 Comparison.png
 

ericgibbs

Joined Jan 29, 2010
16,748
hi,
What is the present charge state of the LI-ION battery?
Have you tried the test when the battery has been fully discharged.?

E
 

ericgibbs

Joined Jan 29, 2010
16,748
@turgut
hi,
As a test , remove the battery and replace with a 5.6R resistor, of suitable 5W wattage, measure the resistor current.
E
Corrected my error!!!
 
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Thread Starter

turgut

Joined Nov 4, 2022
19
i used 2 different test;
1) Two parallel power resistors which 5w & 10ohm
2) A power resistor which 5w 2.2ohm
Results are same. They are not working. I = 0 when i use power resistors as battery. But when im using battery that battery charge near 3.7-3.8V. Current is like in the table. (100-200mA)
Also i did a different thing to understand is my circuit cutting current when battery voltage is higher. So connected a different battery which battery charge is 4.1V. This 2 battery is same brand. They are completely same except their charge. The results like that,
-Battery charge=3.7v Vin=5V I=130mA
-Battery charge=4.1v Vin=5V I=60mA
So current cutting proterty is working. But still im not seeing higher currents like 500-750mA.
 

ericgibbs

Joined Jan 29, 2010
16,748
hi turgut,
Thanks for the information.
I have been searching for LTspice model for the ADP2291 with no success.

I will look again.
E
 
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