# Help with understanding tp4056 and dw01 circuit

Hi,
In the future i plan to start using lipo batteries but I still need to learn and do my homework. I have a few questions regarding the meaning of circuits I find online. TP4056 datasheet is great and details how to wire the chip, but I don't like the example schematic for the dw01 datasheet. Refer to typical application circuit on page 5: vcc and gnd pins are connected to battery terminals on the left (theres a picture of a battery). And then the wires go to very right of the schematic and its written batt + and batt - .. wasn't the battery logo already implying this?? I really don't understand this. It looks like there are 2 batteries on this diagram..

Also, on this typical circuit, we can see CS pin (2) of dw01 is connected to batt -, but Ive read its supposed to be connected to ground instead. And then, the left side of the mosfet connects to the negative terminal of the battery logo? This doesnt make sens, it looks like the mosfet is connected to battery negative on the left and on the right, so its not controlling anything! It should be connected between batt- and ground, not batt- and batt-. What am i missing?

Lastly, i cant tell what we mean by ground. Is ground connected to all the project in that case, like the arduino, etc Id be using, or just the power input like a usb cable I would use to charge the lipo cell?

Thank you for your great help.

Refer to typical application circuit on page 5

The only data sheet I can find has only 3 pages. Can you post a link to the one you are looking at please.

Is ground connected to all the project in that case, like the arduino, etc Id be using,

Yes that is what ground usually means.

The battery icon on the left is indeed the battery. The connections on the right are the rails of whatever is being powered by the battery. So Batt- is actually the system ground, not the negative battery terminal (however the positive battery terminal is directly connected to the system positive rail Batt+). The DW01 does its protection magic by controlling the return current from the system ground to the negative battery terminal. Basically it's just controlling current, and you can do that at either battery terminal, and they chose the negative terminal, I suspect because of the ease of using N-channel mosfets in that arrangement.

So then CS is indeed connected to ground through the resistor.

Great Scott has a couple good Youtube videos on TP4056 circuits.

And note that you can get really cheap modules that contain both the TP4056 and the DW01, or just the TP4056 if your battery already has protection built in, which many do.

What's missing from most modules is "power sharing", which lets you charge the battery correctly while you are operating the device.

ShermanP:
The battery icon on the left is indeed the battery. The connections on the right are the rails of whatever is being powered by the battery. So Batt- is actually the system ground, not the negative battery terminal (however the positive battery terminal is directly connected to the system positive rail Batt+). The DW01 does its protection magic by controlling the return current from the system ground to the negative battery terminal. Basically it's just controlling current, and you can do that at either battery terminal, and they chose the negative terminal, I suspect because of the ease of using N-channel mosfets in that arrangement.

Ok so that's important: batt + and system vcc are directly connected, but doing the same with gnd and batt- would mean no protection at all. That's what the mosfet is doing, controlling current from batt- to gnd, like you said. (and maybe you could set the mosfet between vcc and batt+ instead, like you mention). This makes more sense now.

There is another thing I don't know (sorry for adding questions, but I didn't think I'd solve this so fast). The pin 6 of dw01 is GND pin, but the wiring is different on every circuit I see. And the datasheet doesn't say anything about adding resistors and what not.

1. in datasheet: gnd goes to batt- (not to ground), with a bypass cap between batt+

2. easyEDA TP4056-dw01 circuit: It looks the same, but I don't feel safe because Batt- is written floating next to a wire and I'm not sure what is connected to batt-. this makes me go crazy.. although I'm pretty sure it's pin 6 and mosfets output, I'd love if someone could validate this.
https://easyeda.com/modules/TP4056-DW01-WITH-PROTECTION_510af5b997184e5ca480cb443cb9a304
Also, they added a resistor between batt+ and pin 5 (vcc) instead of connecting it straight to the battery+ like the datasheet did. Why?

3. Great Scott circuit: He does pretty much the same as easyEDA circuit, but the cap between GND and VCC is 0.1 uF instead of 1 uF, just like the datasheet but unlike easyEDA. I guess this doesn't change results a lot..
https://www.instructables.com/id/DIY-LiPo-ChargeProtect5V-Boost-Circuit/

And note that you can get really cheap modules that contain both the TP4056 and the DW01, or just the TP4056 if your battery already has protection built in, which many do.

So yeah, I know modules are available but I really like being able to create my own PCBs, I can't help it. I'd like to be able to create my own product one day!

Thank you so much for your help guys!

The EasyEDA schematic appears to have things reversed from the datasheet, with the negative battery terminal on the right, and labeled BAT-, and ground on the left. But I believe it is the same circuit.

1. in datasheet: gnd goes to batt- (not to ground), with a bypass cap between batt+

Yes, if “batt-” means the negative battery terminal. The GND pin of the DW01 connects to the negative battery terminal.

1. easyEDA TP4056-dw01 circuit: It looks the same, but I don’t feel safe because Batt- is written floating next to a wire and I’m not sure what is connected to batt-. this makes me go crazy… although I’m pretty sure it’s pin 6 and mosfets output, I’d love if someone could validate this.
https://easyeda.com/modules/TP4056-DW01-WITH-PROTECTION_510af5b997184e5ca480cb443cb9a304
Also, they added a resistor between batt+ and pin 5 (vcc) instead of connecting it straight to the battery+ like the datasheet did. Why?

No, the datasheet didn’t connect the Vcc pin to the positive terminal directly. It went through a resistor. The circuits are the same.

Take a look at this page. I think the circuit is a lot better, with B+ and B- being the battery terminals: