Infineon MA12070 Class D

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P

potstip

Member
Joined 2013
Fabianmu said:
Hi,

I had to change the Inductor, due to availability. They are Murata´s 15682C, I thought I had some space left on the Board, now it's getting packed. What is a post-filter feedback?

I noticed that that kicad released v 6.0, my nightly build is stable now, therefore, there isn't an issue anymore with my filetype :)

I attached a pdf with the board layout.
Click to expand...

bucks bunny knows better than most of us, he had a great simple solution for old TPA series. It is a feedback from inductor for more details you can check this document here below;​

https://www.ti.com/lit/pdf/slaa788
But as far as i know MA12070 has feedback already internally (4th Order Feedback Error Control). I do not know is there any way to add extra feedback succesuffy?
 
M

mamocel

Member
Joined 2018
Salvation!
With a little delay ...
Here are the 2 Ma1270 evaluation cards and a 225 w mornsun power supply.
The power supply and the cards are tiny ... Even no fixing holes!
It's too crazy ...
I would have a little modification to make on the bravest one, to put it in PBTL mode.
From what I understand, there is only one solder bridge to reverse ...
Super happy with the Digikey service, they are super fast!
IMG20211228152918_BURST000_COVER.jpg
IMG20211228153123.jpg
 
F

Fabianmu

Member
Joined 2021
HI,
just a short update on my project:
I finally got my PCBs delivered and soldered the first board. I have bought the analogue and I2S versions of the chip and used the analogue version for my first test.
Having a reflow oven and a heat gun is great to get the job done, I don't think I could have it done without it.
Had to play around with the jumper for the correct setting but actually made no routing mistakes on the PCB, I'm super happy that it worked out that well :)

PXL_20220127_172341897.jpg
PXL_20220127_172345001.jpg


The problem I have right now is the increasing noise when I supply the board with more than 10V... below 7 it's not really noticeable. Any suggestions for improvement?

Best Fabian
 
F

Fabianmu

Member
Joined 2021
I figured out that the open Input pins generate the noise. As you can see in the picture, I had only connected IN0A and IN0B, connecting IN1 to a source removes the noise. The board will be used in an active speaker, therefore this should not be an issue, since it will be connected to a source anyway. I did some tests with cable lengths and audible noise starts above 3 m with simple 2x1mm2 wires.

Is it recommended to put in resistors between the inputs and ground? I guess this should help if no input is connected

I have a scope, but I don't think I can measure THD with it. I've heard that it can be done with the ARTA measurement box, should I build one?
 
T

Toku

Member
Joined 2020
Fabianmu said:
I figured out that the open Input pins generate the noise. As you can see in the picture, I had only connected IN0A and IN0B, connecting IN1 to a source removes the noise. The board will be used in an active speaker, therefore this should not be an issue, since it will be connected to a source anyway. I did some tests with cable lengths and audible noise starts above 3 m with simple 2x1mm2 wires.

Is it recommended to put in resistors between the inputs and ground? I guess this should help if no input is connected

I have a scope, but I don't think I can measure THD with it. I've heard that it can be done with the ARTA measurement box, should I build one?
Click to expand...
I ran into the same problem.
If the input is used as an unbalanced input using IN0A and IN1A, noise will occur when the input is open. I stopped connecting IN0B and IN1B directly to GND and tried various things such as grounding with a resistor, but it did not improve.
Eventually I added an op amp to the input.
This noise does not occur when the input is used with a balanced connection of IN0A-IN0B / IN1A-IN1B.
 
F

Fabianmu

Member
Joined 2021
Toku said:
This noise does not occur when the input is used with a balanced connection of IN0A-IN0B / IN1A-IN1B.
Click to expand...
that's exactly what I noticed. I looked up the datasheet (page 22) and it states, that IN0B and IN1B should be tied to ground with a resistor Rs.
Screenshot 2022-02-02 114235.png


The application example (page 8) shows the Resistors RIN0B and RIN1B, but it is not included in the BOM. Maybe a 10k ?
1643799493355.png


What op-amp did you add?

Best
Fabian
 
T

Toku

Member
Joined 2020
Fabianmu said:
that's exactly what I noticed. I looked up the datasheet (page 22) and it states, that IN0B and IN1B should be tied to ground with a resistor Rs.
View attachment 1021161

The application example (page 8) shows the Resistors RIN0B and RIN1B, but it is not included in the BOM. Maybe a 10k ?
View attachment 1021165

What op-amp did you add?

Best
Fabian
Click to expand...
The op amp I used is NE5532.
I tried using the following products experimentally. However, if you use these, pop noise will occur when the power is turned on / off, so additional measures are required.
I also considered a full-fledged balanced input using an input transformer.

In SMSL SA300, the electronic volume of NJW1194 is connected to the input of MA12070.

https://ja.aliexpress.com/item/32804004816.html?gatewayAdapthttps://ja.aliexpress.com/item/32833821366.html?gatewayAdaphttps://ja.aliexpress.com/item/4000847106478.html?gatewayAdapthttps://ja.aliexpress.com/item/4000860020115.html?gatewayAdapt
 
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U

UAN

Member
Joined 2020
frobek said:
My cheap chineese board is based on MA12070P with I2S input, and noise from inductors is present above 10V power supply, no matter if music plays or not. When I replace inductors I will let you know if it solve the problem.
Click to expand...
In the amplifiers RA3s and M100 from Topping and SMSL, there are no inductors at all. Only capacitors. And these amplifiers are certified.
 
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