A ns4150b mobile small power amplifier

Just share your learning process

A novice's job in the electronics industry. I used the ns4150b for a small power amplifier (saw it very cheap when I went to the mall) and added the ip5306 to control the lithium battery for discharge.

Let’s take a look at pcb (: I don’t know why the pcb file shared looks like it has not been drawn, but when opened in the editor, it looks like it has been drawn)

Black and white is so good (:

Next weld

A lump of solder paste

There is no water to wash the board, it is terrible (but it can be used)

Overall view after installation:

The circuit follows the chip manual, but it's not perfect yet.

The charging port uses tyc and is followed by a filter circuit, but the actual verification is that the filtering is not complete and there is still noise.

There is no visible noise when using battery power. The inductor here must use a power inductor . I found an inductor with relatively close parameters according to the manual, which can be obtained from the BOM table below. Please note that! Power inductor !

Next, we need to pay attention to the IC part of the power amplifier.

inp is the signal input place. The three resistors r4, r5, and r6 connected to inp are the input resistors Rin (the following three r7, r8, and r9 are also the same) , which are used to adjust the amplification gain of the power amplifier ic.  

The gain is calculated as A=300k/Rin

The circuit diagram used is 30k and the theoretical gain is 10

The physical verification uses 12k and the calculated gain is 25 (because of the epidemic, I don’t have an oscilloscope to measure at home, so I have no choice)

The switch connected above is for working status control. Pull it low to turn off the amplifier effect.

It is better to use an interface for outputting to the speaker. If I don’t have an interface, I use a pad to solder it directly. If the speaker is not far from the board, the two capacitors can be removed.

The above introduction is completed

Pure hardware training, no software.

Physical verification video is below