#2588 TP4056 Lithium Battery Charging IC

Added: 2026-05-10

[00:00:07]All right, it's chip of the day. People love chip of the day. It is a TP4056 1 amp standalone linear lithium ion battery charger with thermal regulation in SOP 8.

[00:00:20]These things are everywhere.

[00:00:22]All right, it's a complete constant current constant voltage linear charger.

[00:00:26]So, we'll talk about what that means.

[00:00:29]Um and it is just a cute little part. It's just a little 8-bit 8-pin part SO8.

[00:00:36]Um so, what does it need What does it need to do and what does it do? So, it is a chip that charges batteries, okay?

[00:00:44]Charges lithium batteries, right? So, here's a bunch of lithium batteries over here, right? You get the the big ones, the little ones, the the the the tiny ones. You need to You need to charge your batteries. Now, lithium batteries need a particular type of charging circuit.

[00:01:00]And this chip will do that for you, okay?

[00:01:03]And we can take a look at the uh diagram right here.

[00:01:09]Oh, trash man's outside.

[00:01:11]Uh we have uh Wednesday's trash night here, so.

[00:01:16]Uh it is Thursday morning now.

[00:01:19]So, um All right, so um let's talk about these batteries.

[00:01:27]These batteries have a certain capacity and you need to charge them up and you can't overcharge them. It's bad to overcharge them. It's bad to undercharge them.

[00:01:36]Um so, you need to have the right charging conditions. Now, the way that they like to be charged is they like to be charged with a constant current up to a certain point and then they don't like it anymore.

[00:01:47]So, that's what this chip does. It has a section where um it's kind of hard to read this diagram here.

[00:01:56]Um we're going to follow this curve right here. I wish they were in different colors. Maybe I can Let me Let me highlight one.

[00:02:05]Okay, so I'm going to highlight the charge circuit.

[00:02:11]All right.

[00:02:14]There we go, that's better.

[00:02:17]So, the yellow here is the charging uh output. So, first of all, we have a constant current.

[00:02:23]We have a 1,000 mA 1 amp charge current.

[00:02:27]So, we're going to charge that battery and this is the battery voltage.

[00:02:31]So, the battery voltage as you have hold a constant current, the battery voltage will go up and up and up and up and up and up and up.

[00:02:37]And then it will finally reach a particular voltage where oops, we're getting too much and then it starts it turns off the constant current and uh just does constant voltage from there and then it just flat spots. It just goes, okay? So, 4.2 4.2 V is kind of a nominal charge voltage for these types of batteries.

[00:02:59]You don't want to go above 4.2, you don't want to go below 4.2, you want 4.2.

[00:03:04]And even though they're called a 3.7 V battery, you want to charge them to 4.2 V.

[00:03:11]And then they will operate all the way down to about 3 V.

[00:03:14]2 and 1/2 3 V. You don't want to go any lower than that with these batteries, okay?

[00:03:18]So, again, we have There's a little bit of funny business here, but look, we have a charge We have constant current and then constant voltage and because we're holding a constant voltage, the current will go down. We're not forcing a current, we're forcing a voltage.

[00:03:32]Here, we're forcing a a current and we're letting the voltage go up.

[00:03:37]So, this chip does it all does it all for you, okay?

[00:03:51]Here's a typical circuit.

[00:03:53]We have the battery. Battery goes over here and uh there's also a temperature pin, so you can have a thermal couple here um in the battery and if it gets too hot, it'll shut itself down, which is nice.

[00:04:07]Uh so, this is the charge circuit. It's got two outputs for LEDs. It tells you if it's charging or if it's already charged.

[00:04:14]Um so, uh the the charge uh gets pulled down if it's in charge mode, if it's the one 1 amp charge mode.

[00:04:22]And then if it gets up to the voltage current the voltage compliance, then it'll go into the standby mode where it's just sitting there constant voltage.

[00:04:31]And then there's a programming resistor, which tells you how much how much current do you force? I thought And I thought you said it was 1 amp. Well, it's it's variable.

[00:04:40]Depending on what value resistor, you can have it set anything up to 1 amp, okay?

[00:04:45]And so, if you only want 300 mA, you can put in a 4K resistor.

[00:04:50]And uh yeah, there you go.

[00:04:53]So, let's take a look at one in action here.

[00:04:57]Oh, let me uh let me read read you one thing on the data sheet. I told you you you don't want to be below 4.2, you don't want to be above 4.2. Well, how accurate are these things? Well, they're accurate from nominally, they're 4.2, but the chip could be as low as 4.137 or as high as 4.263.

[00:05:20]But this is in an accept in an acceptable range for the battery, okay?

[00:05:25]Um okay, yeah, so let's take a look at one of these.

[00:05:29]All right, so here's a little board that has one of those chips on it.

[00:05:33]And it's got two LEDs.

[00:05:36]A red LED in there and green LED and if it's a red LED, it's charging. If it's green LED, it's already charged.

[00:05:42]You can uh hook up uh USB 5 V. So, this board takes in 5 V and then does all the chargy things.

[00:05:50]Let's put some volts on it here.

[00:05:53]Um should always have 5 V laying around.

[00:05:58]All right, so here's 5 V.

[00:06:02]And there's a little place here where I don't have to hook up USB. I can just hook up 5 V right right here.

[00:06:09]And I don't know if you saw that, but it went from a uh uh flashed from a red to a green.

[00:06:16]And uh if this was uh discharged, it would be uh going uh red and then it will go up to the green, right?

[00:06:27]Um so, let's take a look at a different one. Here's another one. It's using the exact same exact same board.

[00:06:34]And um I have this one hooked up to battery, but this battery is is um It says 1,800 amp hours, okay?

[00:06:49]Uh 1,800 and this 1 amp hours is not marked, but they're usually around 2,000.

[00:06:58]And you want to charge them about half of the uh capacity of the battery.

[00:07:04]The C point is the the the total charge um total capacity. C is capacity.

[00:07:14]Um and these are about 2 amp hour batteries. So, you want to charge it about half of that. So, that's where the 1 amp comes from. You charge this one to about 1 amp. This one's 1,800, so yeah, it's about 1 amp as well, right? 900 mA.

[00:07:27]And so, let's hook this one up.

[00:07:30]And uh see how he's doing.

[00:07:34]And there we go, we're getting a red light on this one. See that?

[00:07:36]So, we have a red light here, which means it's charging, all right?

[00:07:41]And um let's go ahead and take a look on the oscilloscope.

[00:07:48]All righty, take it back. I'm going to use a voltmeter. We'll be able to see it better with a voltmeter.

[00:07:54]And so, I'm going to um look at the voltage on the battery, all right?

[00:08:04]And we will monitor the uh volts here.

[00:08:13]All right, so the battery is currently at 4.17 and we'd like it at 4.2, right?

[00:08:21]So, I'm going to hook up our charge.

[00:08:25]We're going to hook up our our 5 V, it'll turn on the charger. So, now the charger's going. I think you can watch over there, the voltage is now going up.

[00:08:34]There we go, 4.2.

[00:08:37]So, it's almost exactly where it needs to be.

[00:08:41]So, it's not going to take too much longer for the uh charger to go from a red LED to a green LED.

[00:08:53]All right, well, that was chip of the day, a TP4056.

[00:08:57]Like I said, you'll see these things everywhere.

[00:09:00]And uh they do this automatic chargy thing for your lithium ion battery.

[00:09:08]There we go. We've gone to a green green LED.

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