#2574 LN4898 1W Audio Amplifier

Ajouté : 2026-05-05

[00:00:06]All right, it's chip of the day. Today we have a Nat Lineer uh some Taiwanese company maybe. Um not sure. Nat Lineer. Raise your hand if you know who they are. Um it's an LN LN4898.

[00:00:22]not an LM, but an LN uh 48 98.

[00:00:30]And uh it looks like it's an amplifier, although it's all in Chinese. Um, so, uh, it looks like it's going to be a diff amp coming into a section where we have, uh, kind of the, um, pushpull type of thing to the to the speaker. The speaker goes on these two signals here.

[00:00:56]Um, and it wasn't obvious because it's in Chinese, but we can read most of the data sheet. But I did take the PDF and drop it into Grock and said, "Here, please translate." So, it made a very nice translation here. Um, so it's a one watt output for 8 ohm loads. Uses a bridge load structure deliver high quality audio. There you go. Has a built-in shutdown pin. Turn it on and off to save power. It'll operate from uh 3.2 to 12 volts. No need for a couple of capacitors, but for now, we're going to boost our capacitor. So, if you look at something like a LM386, you notice that you have to have a bypass capacitor between the um between the speaker and the device, otherwise it blows itself up. So, raise your hand if you've ever done that. But um yeah, it needs also needs to have a um uh what are they calling a bootstrap here? This is a there's a name for you have a capacitor and and resistor to ground. uh to make it more stable. And um those two things are required on that part. And this one's just good to go.

[00:02:07]You don't need to do any of that stuff.

[00:02:12]Um let's see here.

[00:02:16]Power dissipation 800 600 mill yada yada yada. applications.

[00:02:25]Um, when the power is greater than seven and a half, excessive power output may trigger the chip's internal temperature protection. So, that's nice. It's got that built in. BDD power recommended be no less than one microfarad. Bypass capacitors one microfarad. Yada. You got to have a one microfarad in mine. Um, avoiding voiding avoid shorting the outputs might kill itself. So, don't do that. Um, let's take a look at the Chinese data sheet. This is how it's used.

[00:02:55]So, um, the speaker goes across these two pins and then there's a feedback off of one of them in. So, there's a you can set the gain here with these two resistors.

[00:03:07]They have 100k 220k and then you AC couple it in uh into the thing. So, it's referenced about wherever its other thing is. its other thing is set by this bypass going into the plus end and it's buffered with this one microfarad capacitor. So uh the buffer is is the bypass this it takes the uh it takes the VCC and divides it by two. All right. So uh this side of the op amp kind of thing is going to be two and a half volts and then the other side is going to be 5 volts if that's what you have hooked to.

[00:03:41]Uh you also can do it uh make it diff if you want to.

[00:03:46]Um let's see what are some other numbers we get from the data sheet here.

[00:03:55]Um it's not audio file quality. It's going to be 10% total harmonic plus noise. Uh so you know it's transistor radio type thing. Um there are some graphs that I really don't care about but it's an S so8 package which makes it super super nice.

[00:04:14]So, let's go over and take a look at one. All right, I have it hooked up here. Um, just just like the schematic and the data sheet there. Uh, I have everything all the same values and uh I'm going to bring in a signal and we'll see if it makes a noise on the uh on the speaker. Let's see. Let's go to the uh generator here. Let's see. Oh, I need to uh I need to turn on the power. That's what I'm missing. Hook up 5 volts.

[00:04:50]There we go. And it works. Works just fine. Let's uh go ahead and turn on a sweep just for fun. Here we go.

[00:05:05]I'm sweeping between 1 kHz and 600 hertz. A linear sweep. Uh let's see. How about a logarithmic sweep?

[00:05:15]Same. I don't hear much difference between between those two nearby uh those nearby things. Let's turn off the power here. Yeah, it does seem to uh does seem to do what it seems to do.

[00:05:30]Okay, that was tip of the day. An LN4898.

[00:05:40]>> [music]