I have added a Li-ion battery charging circuit to my project for powering up the whole circuit by taking reference from this site. ( exact same as the commercial board )
The issue I am facing here is maybe related to static charges/MOSFET into hibernation mode.
When I connect the battery the circuit doesn't power up, but when I touch the surface of the circuit where IC DW01A is placed, the circuit does power up and works fine for some time, but the same issue repeats again.
( Maybe the gates of MOSFET get charged when I do touch them )
I have tested this with different ICs and different circuits with the same schematic and I face the same issue.
Has anyone faced this issue? Or does anyone know what's actually happening and what I should do to avoid this?
Also, the circuit works fine when the battery and the charger both are connected at the same time. ( It doesn't with only the battery connected. )
One version of the datasheet for the DW01 has this:
Note: When a battery is connected to
DW01-G for the first time, it may not enter
the normal condition (dischargeable may
not be enabled). In this case, short the CS
and VSS pins or connect to a charger to
restore to the normal condition.
So the question is - if you first connect the battery, and the circuit does not power up, what happens if you temporarily connect the charging source? Does the circuit power up, and does it stay powered up when you remove the charging source?
Edit: I should say that I don't see this behavior in the TP4056 modules I get from Ebay or Banggood. They typically have a DW01A chip, and in my experience they start up in normal mode when a battery is connected.
Edit2: I take it back. I found a TP4056 module that does behave that way. With no load, the output voltage reads about 1.3V when I first connect the battery. When I plug in USB, it goes to 3V, and stays there when I disconnect USB. So I suspect that is your problem. But, if you install the load sharing circuit dicussed on page 2 of your link, it's possible that may go away.
One thing about your circuit that probably has nothing to do with your problem is that you have arranged R27 and R32, both 10K, so you have a voltage divider at the gate. So the maximum gate voltage is 2.5V. That's probably enough to turn on the mosfet, but the better design is to put the connection to R32 to the left of R27. Or you can approximate that by just changing R32 to 100K.
Also, does VUSB_detect have a pull-down resistor? There's nothing in the circuit that would ever bring it low.
Hello ShermanP, thank you for your reply.
Well here,
If I connect the charging source the circuit does power up ( with full voltage i.e. 3.3V) but when I remove it, the circuit doesn't power up, it provides around 2.5 V and it fluctuates around that range.
Initially, with only battery connected, circuit doesn't power up. CS and OC pin outputs 2.5V. But when I touch the IC or if I connect the charger, CS and OC pin outputs 3.3V and circuit power ups. Why is that so?
I am not able to power up the circuit with only the battery connected without any other interference.
With the battery connected, if you connect the charging source and the output goes to 3.3V, does it stay at 3.3V when you disconnnect the charging source, or does it drop back down?
See post #15 and following. It may be that reducing the value of your C14 could fix it. But also see the stackexchange link at the very end for another possible fix - connecting a capacitor between pin 2 (CS) and pin 6 (GND).
I have gone through these links and implemented the fix as well, but nothing worked for me.
Well I think the main problem is with the IC DW01A itself ( from the production ), because when I use the ICs that I have ordered, the OD pin is LOW with the same circuit and when I took the IC from the module itself, OD pin is high and everything works just fine.
Do you think there's something else wrong here rather than IC being faulty?
I've asked this twice, but you haven't answered. But if the DW01 operates properly on battery alone after it has been kick-started the first time, then this need for a kick-start may be a variation among manufacturers.
When you say that the chip from the module works properly in your circuit, is everything else the same, including the same load? If so, then it seems your circuit must be ok, and the chip is the problem.
Sorry @ShermanP
Well I did say about that here, if I connect the charging source it does power up and stays on even after I remove the charger but when I shut down the circuit and try to turn it on again, it doesn't power up without the charging source.
I have connected charger many times, but after some time it starts to behave the same. In my case kickstart hint is not working.
And yes, everything is same including the load too when I am testing the IC from the module itself, so maybe the chip is the problem.
If you shut down the load, but do not disconnect the battery from the DW01, then it should power up again without connecting the charging source. There are billions of protected lithium batteries in the world with this DW01 circuit. Once the battery has been connected to the DW01, and it has been jump started if necessary, the mosfets will always be on when the battery is connected to a load. If yours does not behave that way, then something is wrong with the chip or your circuit. And if a DW01 from another source does work that way, then I think the chip must be the problem. Of course that's assuming that none of the protection parameters, like over discharge, are being triggered.
But even with a good chip, you may have this problem when you replace batteries, because then the DW01 loses power. In testing my protected TP4056 modules, I found that I did not need to attach the charging source if there was no load when I replaced batteries. But with 100 ohms across the output, I did have to connect the source. So the load appears to make a difference.
I don't know of another protection chip alternative.
Wait,
What do you mean by "DW01 loses power" when we replace batteries. So in this case, what you are suggesting is the circuit with load connected will work fine when we kickstart the IC by charging source and keep the battery in the socket ( i.e. without replacing the battery ) and it will work fine unless we remove the power to the DW01?
Yes, I think that's right. As long as you don't disconnect the battery from the DW01, it should continue to work properly after the initial kick start (If it needs one). That's true of every protected battery. Once the battery and protection circuit are assembled, they are never disconnected. So when you put a protected battery into a flashlight, you don't have to connect the charging source. It provides power just like an unprotected battery. Even if protection is triggered because of over discharge, the DW01 is still being powered by the battery (at about 1uA). But of course in that case you will have to connect the charging source anyway to recharge the battery.
The blurb in the datasheet begins with "When a battery is connected to DW01-G for the first time...".
So as long as you don't need to replace the battery, you should be able to charge and discharge normally, with no kick-starting. That has always been my experience with TP4056 modules and other devices using the same circuit.
You are right. I used to replace the batteries with the circuits. Now that I am testing the circuits with the battery connected and kickstarting the circuit once, it does work properly unless I remove the battery.
I got confused, when I used to test my circuits with batteries some of them used to power up and some didn't. How come the same IC needs kickstart and some doesn't for the same circuit? I didn't get this. Maybe the gate of the MOSFET ( connected to B- and ground ) used to get charged by some reason.
But, in the end it does work properly if I do connect the battery without replacing it.
Thank you @ShermanP for helping me out. I will mark this as a solution now.
Happy to help. I still wonder if there's a way to modify the standard datasheet circuit so kick-starting is never required, but without compromising the protection.
