Finished PCB

 

How many mA can this setup with TP2202-5 handle ? Do I have to change the capacitor values for 100-150 mA ?
It throttles with this load. Is the 24 to 5v voltage drop too high ? Would a zener diode in front help, what value ?

 

The data sheet for the TP2202-5 will provide that information as well as heat sinking requirements.

 

It throttles with this load.

What does that mean and what are you trying to do now?
A resistor in series would help reduce the dissipation on the regulator. For 150ma load a 110 ohm 5 watt resistor would lower the dissipation from 2.85 watts to .375 watts on the chip. Kind of hard to heat sink a SOT23-5
Better to use a separate 5 volt regulator that can be properly heatsink.

 

Caps on the output of a regulator are generally used for stability and provide a better transitional response, not provide more current.

 

Caps on the output of a regulator are generally used for stability and provide a better transitional response, not provide more current.

Capacitors typically 0.1 MFD, installed close to both input and output of monolithic regulators. This is even more important when a series resistor is used to reduce heating in the regulator. These caps are in addition to higher value electrolytic caps, because they prevent the much higher frequency oscillations.

 

Thanks. The 5v 100mA is for a bluetooth module. I use 1 uF, but there is still a lot of AC adapter noise (hissing). How do I reduce the AC adapter noise ?

 

The standard approach is a shunt capacitor followed by a series inductance followed by a second shunt capacitor. The inductor must have a low enough resistance to not cause an excessive voltage drop at the required current, and enough inductance to present an adequate impedance at the main noise frequency. In addition, the inductor core must not become saturated at the operating current.

 

Is it better to use a B2405S-1W to reduce the noise ?

 

Is it better to use a B2405S-1W to reduce the noise ?

Don't know. Have you tried larger caps on the input and output of the TP2202-5?

 

Don't know. Have you tried larger caps on the input and output of the TP2202-5?

Like 10uF ? (Currently 1uF)

 

Leave the 1uf on the input but try 10uf on output.

 

A shunting capacitor produces a voltage divider effect reduction, and if the effective source impedance of the noise generation is much less than the series impedance of the shunt capacitor, the noise amplitude reduction will probably not be adequate. THAT is why I suggest a series filter choke selected based on the noise frequency spectrum. Certainly this is more complex and costs more, but if it completely solves the problem, perhaps the value exceeds the cost. But if cost is the only consideration that is a separate issue.

 

Noise enlarged

 

OK, and while the time scale is not clear, ( is the "M" milliseconds or minutes?), it seems to be fairly constant, although the peak seems to be different. Is this the output of the supply? Measured between the supply negative terminal and the supply terminal?
Is this with the system connected and drawing the normal operating current???
And with the amplitude given in (millivolts??) it is a challenge to tell exactly what magnitude we are dealing with.
I assume that the measurement is AC coupled, as it seems very much centered about the average.

If the guess that this is the supply output at the input of the system, then the suggestion of a series filter inductance (filter choke) still holds. The DC resistance should be low enough to not cause more than a tenth of a volt drop during normal operation, and the current rating should be a bit more than the operating current. Those specifications should allow some freedom of choice.

 

Please let me try to put it another way: How do I best connect the BT module with the mono amplifier board (both audio and power), to limit idle noise as much as possible ?

XH-M542 don't have 5 or 3.3v, only 24v
XH-M542 input impedance is 10K
-IN and -Vcc are connected on the XH-M542
GND and AGND are connected on the TSA6179
Power is 24V

 

Shown are the audio connections. Combining Left and Right channels of the BT through the 1K mixing resistors for the mono input of the XH-M542.
As far as power I think you just need a clean 5 volt regulator powered from the 24 volt supply.

View attachment 296228

Thanks. Is mounting the 24v to 5v regulator close to the BT board a (noise) problem ?

 

Sorry my previous post is incorrect. The XM-M542 has a differential inputs and requires input capacitors as shown

 

Thanks. Is mounting the 24v to 5v regulator close to the BT board a (noise) problem ?

I wouldn't think so.

 

Sorry my previous post is incorrect. The XM-M542 has a differential inputs and requires input capacitors as shown
View attachment 296233

Differential input ? Are you sure ?